The Brown Recluse Spider 9780801456169

Table of contents :
Contents
Acknowledgments
Introduction
1. Taxonomy
2. Identification
3. Misidentification
4. Life History and Biology
5. Distribution
6. Medical Aspects
7. Medical Misdiagnoses
8. Human Psychology and the Brown Recluse Spider
9. Bites and Alleged Bites by Other Spiders
10. Control Measures
Glossary
References and Further Reading
Index

Citation preview

The

BROWN RECLUSE SPIDER

The

BROWN RECLUSE SPIDER R ICH A R D S . V ET T ER

Comstock Publishing Associates

a division of Cornell University Press Ithaca and London

Copyright © 2015 by Cornell University All rights reserved. Except for brief quotations in a review, this book, or parts thereof, must not be reproduced in any form without permission in writing from the publisher. For information, address Cornell University Press, Sage House, 512 East State Street, Ithaca, New York 14850. First published 2015 by Cornell University Press First printing, Cornell Paperbacks, 2015 Printed in the United States of America Library of Congress Cataloging-in-Publication Data Vetter, Richard S., 1955– author. The brown recluse spider / Richard S. Vetter. pages cm Includes bibliographical references and index. ISBN 978-0-8014-5399-1 (cloth : alk. paper) ISBN 978-0-8014-7985-4 (pbk. : alk. paper) 1. Brown recluse spider. I. Title. QL458.42.L6V48 2015 595.4ʹ4—dc23 2014039853 Cornell University Press strives to use environmentally responsible suppliers and materials to the fullest extent possible in the publishing of its books. Such materials include vegetable-based, low-VOC inks and acid-free papers that are recycled, totally chlorine-free, or partly composed of nonwood fibers. For further information, visit our website at www.cornellpress.cornell.edu. Cloth printing Paperback printing

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Cover photograph by Richard S. Vetter.

CONTENTS

Acknowledgments

vii

Introduction 1 1 | Taxonomy

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2 | Identification 11 3 | Misidentification 21 4 | Life History and Biology 5 | Distribution

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71

6 | Medical Aspects

91

7 | Medical Misdiagnoses

113

8 | Human Psychology and the Brown Recluse Spider 125 9 | Bites and Alleged Bites by Other Spiders 10 | Control Measures Glossary

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163

References and Further Reading Index

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167

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ACKNOWLEDGMENTS

I thank Kitty Liu, Susan Specter, and Peter Potter of Cornell University Press for helping turn my goal of publishing this book into a reality. Two anonymous reviewers made comments on the first draft and Gavin Lewis made many comments on the final draft that greatly improved the end product. Diane Barger reviewed the chapter “Life History and Biology” and the late Dr. Gary Wasserman of the University of Missouri– Kansas City School of Medicine and the Children’s Mercy Hospital, who reviewed “Medical Aspects” and “Medical Misdiagnoses,” each provided valuable comments and suggestions. I acknowledge dear friend Mary Ursula Holden, who, after spending her days at her official profession of book editing, did me the generous favor of using her crepuscular and nocturnal hours to work on this book as well. Much knowledge was gained over the years from my association with the Barger family (Diane, Brenna, Dale, and Bradley) of Lenexa, Kansas, who willingly turned their 1850s-built, brown recluse–populated home into a live-in laboratory where we collaborated on several studies of the species. Appreciation goes out to Rachel Kuypers, who allowed me to use an image of her smiling face after she suffered a mild brown recluse envenomation. I appreciate my association with many medical colleagues over the years who helped me understand the medical aspects of loxoscelism while eagerly absorbing in exchange biological and taxonomic information that I offered regarding brown recluses and other spiders. In particular, I must single out the following dermatologists for their understanding and tutoring: Dr. David Swanson, Dr. W. Van Stoecker, and Dr. Gary Wasserman. I acknowledge the dozens of my arachnological colleagues, many being members of the American Arachnological Society, with whom much recluse information has been vii

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ACKNOWLEDGMENTS

exchanged over the last two decades. Finally, I appreciate the scores of pest control personnel, entomologists, and public health officials, and the hundreds of homeowners who submitted spiders for identification, who thereby made possible a better understanding of recluse spider distribution in North America

The

BROWN RECLUSE SPIDER

INTRODUCTION

The brown recluse is a very common house spider in specific parts of the United States and can be found by the hundreds in the proper environment. Originally it was just a small brown creature in which very few people, including arachnologists and medical personnel, took any interest, but it came to national prominence in the United States after 1957, when it was determined to be the source of dramatic skin lesions in humans. During the 1960s, there was a rush to generate information regarding its biology, life history traits, venom composition, and envenomation consequences. Brown recluse bites usually do not lead to severe symptoms, but about 10% of cases develop necrotic (rotting flesh) lesions that may require skin grafting. In very rare conditions in North America (fewer than 1% of cases), a systemic reaction can occur, most often in children, which can be fatal if not diagnosed and remedied quickly. As a result, the brown recluse now induces fear where it is found, and even where it is not found: the brown recluse’s infamous reputation causes people to believe they see this spider in parts of North America where it does not exist. The brown recluse spider is therefore a source of much concern for homeowners, especially those buying or selling houses, and it provides significant revenue for the pest control industry. Spiders in general share an infamous reputation with bats and snakes, the result of guilt by association with the few members of each group that are actually harmful. In fact, only two main North American spider groups are recognized as truly causing threats to human health: the widows and the recluses. Among the former, the black widow is well researched, its medical effects are well established, and the biological aspects of its life history are well known. However, knowledge of the brown recluse lags behind the wealth of information for the black widow, and as a 1

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INTRODUCTION

result, misinformation and misconceptions fill the gaps between popular thought and arachnological knowledge. Although in most cases this merely results in the telling and retelling of harmless myths, the reiteration of these myths can sometimes cause real damage. One example of this damage occurs when ill-informed physicians diagnose brown recluse spider bites as the cause of skin lesions in areas of the continent where recluse spiders of any species are exceedingly rare or have never been found. When the quantity of brown recluse bite diagnoses greatly outnumbers the verified specimens of recluse spiders in a particular area, it logically follows that the spiders cannot be responsible for all these incidents. Some of these misdiagnosed skin conditions, such as cancer, lymphoma, group A Streptococcus bacterial infection, and Lyme disease, can cause great suffering, irreversible damage, and possibly death. When a wrong diagnosis is made, spider bite treatment is ineffective and the correct treatment is delayed or never given. A second example of myth overriding fact involves misidentification of harmless spiders as brown recluses. Most of the North American human population living outside indigenous brown recluse spider territory do not have the sufficient skills to accurately identify the spider. Or rather, because these people are unaware of the actual identity of the many spiders that they perceive to look similar to brown recluses, many harmless spiders are misidentified as such. This can lead to unnecessary, inappropriate, and occasionally dangerous abuse of insecticides or other pest control methods, which are more threatening to human health than the spiders. At the time of writing, there was no widely available work for the general public summarizing the state of knowledge regarding the brown recluse and other recluse spiders in North America. This book attempts to fill this gap. Of course, much of the information provided here is based on the scientific literature, listed in the references under the applicable chapter heading. Other sources include the unpublished knowledge of local authorities who have dealt with the brown recluse spider for decades. Surprisingly, for some aspects such as local distribution within various states, oral history is the best available source of knowledge. Basic information for the general public is provided here, along with sufficient scientific data to make this book a worthwhile contribution to the field of arachnology. Some readers may skim topics they already know and others may struggle through more difficult material, such as unfamiliar medical aspects. Common names for spider species are used where

INTRODUCTION

they exist, but in order to provide scientists with the most accurate research results, the spiders’ scientific names are also given. In this way, the book can be a resource for readers at all levels. It can provide information to the general public about these spiders that so thoroughly grip the American psyche; it can dispel and defuse the mythology surrounding them, replacing hyperbolic hearsay and word of mouth with scientifically accurate information; and it may also spur other arachnologists to study the brown recluse. Finally, this book describes some of the procedures occurring behind museum walls and university doors, and thereby gives readers both a historical and a behind-the-scenes view of how science works in a particular field, how it has advanced to the present state of knowledge, and perhaps also where it is going. Often the task of describing species may appear very dry and boring but it also involves the most fascinating detective work, which the scientist pursues in awareness of the steps (and missteps) of the people who contributed early on and helped define the field for the future. It is like looking into a stream and realizing how much water has flowed past but also how much more will flow for decades to come. It gives the scientist a feeling for his or her place in time and in the field.

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TAXONOMY

It is best to start by describing where the brown recluse fits into the grand scientific scheme of things—its classification as a species, which will serve as a reference point. The biological classification system can seem confusing or even overwhelming with its sometimes long and unfamiliar terminology, but it is really just a series of steps that move downward from one category to a lesser one. The classification scheme for the brown recluse spider, then, is as follows: Kingdom: Animalia Phylum: Arthropoda Class: Arachnida Order: Araneae Infraorder: Araneomorphae Family: Sicariidae Genus: Loxosceles Species (or specific epithet): reclusa Spiders are in the kingdom Animalia. They belong to the phylum Arthropoda (creatures with “jointed feet or legs”), which contains many familiar groupings of animals such as insects, crustaceans, millipedes, and centipedes. Moving further down the categories of classification, spiders are in the class Arachnida. Members of this class have eight legs in adult form and mouthparts called chelicerae (singular: chelicera). (The chelicerae in spiders are the movable mouthparts to which the fangs attach.) Spiders are in the order Araneae; other arachnid orders include, for example, the Scorpiones (scorpions), Acari (mites and ticks), Opiliones (daddy longlegs—but not the daddy longlegs spiders which of course are in the order Araneae), and Uropygida (vinegaroons). 5

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Within the order Araneae there are in turn many subdivisions. There are three infraorders, of which the most primitive is a “missing link,” the Liphistiomorphae, which are not found in North America but are of great interest to arachnologists studying the evolution of spiders. The remaining two infraorders are the Mygalomorphae and the Araneomorphae. The mygalomorphs are slow-growing spiders with many ancestral features, and include the tarantulas and other closely related species. The araneomorphs are known as the “true” spiders, but a better name would be the “common” spiders; in any case, the recluse spiders belong to this group. Within the araneomorphs, two large divisions are found: haplogynes and entelegynes. Haplogyne means “simple female,” which describes the relatively primitive structure of the female reproductive organs of this group. In comparison, the entelegynes (meaning “complete females”) have more complicated reproductive structures. Brown recluse spiders belong to the haplogynes, which causes difficulty in species determination because of the simple structure of their reproductive organs, which does not allow for easily observable variation among species. Farther down the classification ladder are the genus and species names. which are combined to form the scientific name of any particular organism, also known as the binomial (“double name”). Usually, the two parts of the binomial are derived from Latin or Greek. For example, the honey bee’s  scientific name is Apis mellifera: apis is the Latin word for “bee” and  mellifera means “honey-bearing.” The species name, or specific epithet, may also give a hint regarding some physical feature of the organism. For example, the specific epithet of the spider Steatoda albomaculata translates as “white-spotted,” from the markings on this species’ abdomen. The scientific name for the brown recluse spider is Loxosceles reclusa. The  genus name, Loxosceles, is pronounced “locks-AW-sel-eez,” which rhymes somewhat with the well-known isosceles triangle (“triangle with equal legs”) from geometry class and is formed from  two Greek words: “Loxos-” is from the word for “slanted, crooked” and “-celes” is from the word for “legs.” The name “slanted legs” comes from the way spiders of this genus hold their legs when at rest (Fig. 1.1). The specific epithet reclusa is an obvious reference to the behavior of these spiders in seeking places to hide, although this is a characteristic of many species of spiders of many genera. So far as the common name “brown recluse spider” is concerned, this book conforms to the strict scientific practice of using such a common name to refer only to one species, not to a group of several species—in this

TAXONOMY

Fig. 1.1. The genus name of the recluse spiders, Loxosceles, comes from the Greek for “slanted legs” because of the way in which the spider positions itself at rest. This spider is a male Chilean recluse, Loxosceles laeta.

case, to Loxosceles reclusa, which is found almost exclusively in the south and central midwestern United States. In North America, several other Loxosceles species have common names; the desert recluse spider found in the deserts of Arizona and southeastern California is named Loxosceles deserta, the Big Bend recluse found in southern Texas is Loxosceles blanda, the Apache recluse is Loxosceles apachea. Many other Loxosceles species found throughout the world do not have common names quite simply because they are not common; many are only known from a handful of specimens and are often found only in the one location where the original specimens were discovered. However, as a genus, the Loxosceles spiders are also known in North America as violin spiders, fiddle back spiders, or recluse spiders. In South America, Loxosceles spiders are referred to simply as brown spiders—a poorly conceived and simplistic common name, because so many spiders of entirely different genera are also brown. In this book, the Loxosceles genus in general is referred to as “recluse spiders.” However, nonarachnologists frequently refer to any spider of the genus

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Loxosceles as a “brown recluse spider,” although this is not technically correct. For most aspects, including the medical, this is mainly a semantic argument, because what pertains to the brown recluse spider medically pertains with minor variations to all recluse spiders. Nevertheless, there are some behavioral and physical differences between the brown recluse spider and various closely related species, so it is important to be careful when using common names. One additional aspect of scientific naming is that sometimes changes occur. This is something that nonscientists may find odd; it would seem that once an animal or plant receives a scientific name or classification grouping, it should stick forever. Unfortunately, this is not the case. Scientists discover more species and determine new evolutionary relationships by spending more effort examining a group of organisms; new technology such as the scanning electron microscope or techniques to determine DNA sequences enables scientists to discover new information about organisms; and sometimes the accumulation of this new knowledge leads to changes in how organisms are lumped together or split apart in the hierarchy of categories. For example, several spider species were dispersed around the world before arachnologists starting naming them. Arachnologists on different continents then gave names to their local spiders, and sometimes the same species was given several scientific names by different people working independently. Decades later when there was better communication worldwide, this or that researcher realized that these specimens from different areas of the world were all the same species, whereupon the oldest specific epithet took priority and the other epithets became obsolete. As a result, a very common scientific name that might have been frequently used in the literature might become no longer valid—as indeed happened in the case of the first recluse spider species named in Europe. The first recluse spider specimen was named Scytodes rufescens in 1820. The genus name Loxosceles was erected in 1832 for a circum-Mediterranean spider at the time named Loxosceles citigrada. This same species was given several additional names until, in 1873, the youthful French arachnology prodigy Eugène Simon examined the different specimens, decided that they were indeed all the same species, and settled on the name Loxosceles rufescens. (Simon published his first spider taxonomy book, which is still considered to be a classic, when he was only 16 years old.) Not surprisingly, the Europeans were very active in naming Old World animals because the European scientific world was far more developed than that of the Western Hemisphere at the time. As the spider fauna of the New World

TAXONOMY

became better known, sometimes they were given Old World names because the spiders were thought to be the same species. Years later, after more specimens were collected from different areas of the world and greater scrutiny was applied to these, specific epithets were created to describe them. Until then, however, an older, incorrect name was often used for the sake of convenience. For example, the brown recluse spider of North America was long known by the European name Loxosceles rufescens, and did not receive its scientific name until 1940 when American arachnological luminary Willis Gertsch and his colleague Stanley Mulaik designated it Loxosceles reclusus. (Gertsch gave scientific names to all forty-eight species of Loxosceles spiders of Central and North America and the Caribbean Islands.) Several scientific papers published before 1940 use the old, incorrect name, which can lead to confusion among readers who are not aware of the history of the brown recluse’s scientific nomenclature. Another problem arises from the fact that the Greek and Latin languages from which scientific names are derived assign grammatical gender to all nouns and the adjectives that modify them; thus, the specific epithet (usually an adjective) has to have the same gender as the genus name (usually a noun). Although the recluse spider genus name has never changed, when Gertsch and Mulaik originally named the brown recluse spider, they mistook the genus name Loxosceles as masculine and used the specific epithet reclusus—the masculine form of the adjective. However, Loxosceles is one of many ambiguous Greek words that can be read as either masculine or feminine; it is actually feminine. Later, in 1958, Gertsch realized this mistake and changed the species name to the correct, feminine form, reclusa, which is how it now stands. That is also why one finds many other Loxosceles species ending with the feminine “-a” form such as deserta, arizonica, blanda, and laeta. Another major area of potential confusion caused by the ever-evolving field of science involves the family to which the Loxosceles spiders belong. Regardless of its own stable name, the genus has continually moved to and fro between families over the centuries. Originally, Eugène Simon assigned it to the family Sicariidae, named after the spider genus Sicarius from South Africa and South America. In 1940, when Gertsch and Mulaik named the brown recluse spider, they placed the genus Loxosceles in the family Scytodidae, named after the closely related and harmless spitting spiders of the genus Scytodes, which are found throughout the world. Changing his mind after studying many other specimens, Gertsch then moved the Loxosceles

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genus to its own eponymous family, the Loxoscelidae, in 1949. With more study of the South American Loxosceles, Gertsch then moved the genus back to the Scytodidae in 1958, and then again back to the Loxoscelidae by 1983. Then in 1991, a group of arachnologists examining the silk-emitting structures of many different spiders decided that recluse spiders should be placed back in the family Sicariidae—exactly where it originally started and now currently stands. The Loxosceles spiders and the African spiders of the genus Sicarius both have the same destructive venom enzyme leading to nasty skin lesions in humans, and hence this interpretation of their taxonomic relationship seems justified. But then again, additional research may bounce them over to another family someday. About one hundred species of Loxosceles spiders are currently known in the world, with over eighty found in the Western Hemisphere and eleven native species in the United States. There are also two rarely collected North American nonnative species with very limited distribution. No populations of any species of recluse spiders are known to exist in Canada. Below, the North American spiders are listed by common name and scientific name; they are grouped by native and nonnative, and by wide and limited distribution. North American Recluse Spiders with Wide Distribution Brown recluse spider Texas recluse spider Big Bend recluse spider Apache recluse spider Arizona recluse spider Desert recluse spider

Loxosceles reclusa Loxosceles devia Loxosceles blanda Loxosceles apachea Loxosceles arizonica Loxosceles deserta

North American Recluse Spiders with Very Limited Distribution Grand Canyon recluse spider Russell recluse spider Baja recluse spider Tucson recluse spider Martha recluse spider

Loxosceles kaiba Loxosceles russelli Loxosceles palma Loxosceles sabina Loxosceles martha

Nonnative Recluse Spiders Occasionally Found in North America Mediterranean recluse spider Chilean recluse spider

Loxosceles rufescens Loxosceles laeta

2

IDENTIFICATION

Identification of spiders in general is not an easily accomplished task. It takes arachnologists years of persistent study in order to know the features and structures characterizing most spider species. In some cases, however, the physical aspects of a species are so characteristic that it is very easy to teach a nonarachnologist how to identify a particular spider. Examples include the black widow, a shiny, jet-black spider with a round abdomen and a red hourglass on its belly; the black and yellow garden spider, which hangs conspicuously during the daytime in gardens throughout North America and has a series of black and yellow stripes on its abdomen; and the bold jumping spider, which is black with white triangles on its abdomen and iridescent green mouthparts. Identification of the brown recluse spider is somewhat simple. However the infamy of the spider and the misidentification of many harmless spiders as brown recluses have led to much confusion, mostly about the violin-shaped pattern on the cephalothorax (Fig. 2.1): nonarachnologists routinely see violins on many harmless spiders. Presented below is information about other characteristics, which will provide a much better method for identifying recluse spiders.

Anatomy Explanations of spider anatomy typically start with a comparison to insects because these are the arthropods with which most people are familiar. Insects have three body sections: the head (which contains the eyes, other critical sensory organs like antennae, complex nerve organs, and mouthparts); the thorax (to which the legs and wings are attached, and which contains associated muscles for movement); and the abdomen 11

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Fig. 2.1. A brown recluse spider, showing the violin pattern on the cephalothorax.

(which contains most of the digestive and reproductive organs). In contrast, spiders have only two major body sections: the cephalothorax, in which the head and thorax are fused together, with the legs attached; and the abdomen, as with insects (Fig. 2.2). The top side of the spider is called the dorsal surface, and the underside is called the ventral surface.

Eye Patterns and Dorsal Markings The most consistent and definitive aspect identifying a spider as a brown recluse is the eye pattern. Most spiders have eight eyes on the front dorsal portion of the cephalothorax, usually in two rows of four. Loxosceles spiders belong to one of the few genera of spiders possessing six eyes arranged in pairs. There is one pair of eyes at the front of the cephalothorax and additional pairs on either side with a definite gap between the pairs in a gently curved U-shaped pattern (Fig. 2.3). They are “recurved,” meaning that the arms of the U point toward the back of the spider’s body (if the arms point toward the front, the eyes are “procurved”). This pattern of recurved eyes does not vary among the hundred or so species of recluse

Fig. 2.2 . Anatomy of a brown recluse spider showing only the right side appendages. This image is based on a male spider; females have shorter legs.

Fig. 2.3. Cephalic region showing the pattern of the six eyes and the violin-shaped marking.

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spiders worldwide, and is easily observable with a magnifying glass and quite often with the unaided eye. This is the feature that should be used to identify spiders as recluses because it is so much more diagnostic than the violin pattern. A very easily observable dark brown violin pattern does indeed usually occur on the dorsal surface of the tan-colored cephalothorax of the brown recluse spider (Fig. 2.3). This violin is defined by brown pigment on the surface as well as a series of seven lines of little hairs aligned longitudinally on the violin and pointing toward the front of the spider’s body, with the “fretboard” of the violin pointing backward toward the abdomen. This pattern is rather consistent in most brown recluses, but one must be aware of the occasional variation. In young and recently molted brown recluse spiders, the violin pattern may not be very distinct and can be entirely absent (see Figs. 4.9, 4.17). In many of the native southwestern American recluse spiders such as the desert recluse (Fig. 2.4) and the Big Bend recluse (Fig. 2.5), there is minimal or no pigmentation in the violin area, though

Fig. 2.4 . The desert recluse, Loxosceles deserta, typically lacks pigmentation in the violin area and is almost uniformly colored, but the seven rows of hairs in the cephalic region may give the impression of a violin pattern.

IDENTIFICATION

Fig. 2.5. The Big Bend recluse, Loxosceles blanda, has little pigmentation in the cephalic region.

one can occasionally see a violin pattern at the suitable lighting angle because of the reflection off the seven rows of hairs on the cephalothorax. However, because of the variation in the brown recluse spider’s violin pattern and because other American recluse spiders often lack a definite violin shape, one should not use the violin as the definitive identifying feature for recluse spider identification. Unfortunately, this feature is repeatedly stated, including in medical publications, to be the only feature needed for recluse identification, which has resulted in misidentifications and will continue to do as so long as the more reliable means of identification are not well known. The abdomen of the brown recluse spider is another feature that nonarachnologists try to use for identification. The abdomen is covered with very fine hairs and is uniform in coloration which can vary from a light cream or tan color to a very dark brown, depending upon what the spider eats: brown recluses fed crickets or termites have light tan abdomens and recluses fed house flies have dark abdomens (Fig. 2.6). This variation in abdomen color confuses many nonarachnologists who use

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Fig. 2.6. This brown recluse spider was first fed crickets, resulting in a pale abdomen (left); a week later, the same spider was fed two house fl ies, which caused the abdomen to darken (right).

books or Internet photos to identify specimens, leading to uncertainty or misidentifications, and should not be used to identify brown recluses. Additionally, although all species of recluse spiders found in North America have uniformly colored abdomens no matter the actual shade, one must be aware that the cardiac region (on the dorsal abdominal surface near the cephalothorax, see Fig. 2.2) is sometimes a different shade of color because the exoskeleton is so thin that the internal organs can be seen through the skin. It appears as an elongate diamond or elliptical shape that is slightly darker than the abdomen. This cardiac mark is commonly seen in other, nonrecluse spiders as well, so it cannot be used to identify a spider as a brown recluse. Identification of recluses is also complicated by the fact that a close relative, spitting spiders of the genus Scytodes, shares the same eye pattern. However, these spiders have several other features that readily distinguish them from recluse spiders. Because the resemblance often leads to misidentifications, the spitting spiders will be covered in more detail in the next chapter.

Reproductive Structures In addition to eye patterns and body markings that are easily seen by nonarachnologists, reproductive structures can be studied by arachnologists in hopes of verifying species identification. Because most spiders do

IDENTIFICATION

not have good vision, one way they avoid mating with the wrong species is to have reproductive structures similar to a lock-and-key mechanism where the male mating organ only fits the female reproductive openings of the same species. Spiders also use pheromones, behavioral sequences, and sometimes acoustic vibrations in the mating process. From the point of view of identification, though, what matters most is that reproductive structures have evolved to be very similar within one species and usually very different between species, and therefore can be used to define and distinguish species. However, recluse spiders are haplogynes (“simple female” species) and have very simple reproductive structures, so that variation is minor among the different species. This often makes it difficult for arachnologists to assign species names to Loxosceles specimens with confidence based on this feature. In male spiders of all species, the reproductive structures are on the terminal end of the palps. In entelegyne (“complete female”) spiders, the palp is usually very complex with lots of structures on its surface. However, in the recluses, the male palp is a simple bulb (Figs. 2.2, 2.7) with a

Fig. 2.7. The male mating organ is at the end of the pedipalp and looks like a rounded bulb with a saber-like structure (embolus) which is inserted into the female reproductive tract.

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Fig. 2.8. Reproductive organs of the brown recluse (left), desert recluse (center) and Mediterranean recluse (right), with male structures at top and female structures at bottom.

saber-like pointed embolus (the part inserted into the female’s reproductive opening). Only slight differences in the male reproductive structures differentiate the brown recluse, desert recluse, and Mediterranean recluse (Fig. 2.8, top row). For the experienced arachnologist, the differences are as follows: in the brown recluse, the tip of the embolus looks like the beveled point of a hypodermic needle or a syringe with its end cut off with a sharp blade (Fig. 2.8, top left); in the desert recluse, the bottom portion of the embolus is thicker and curved at the tip (Fig. 2.8, top center); and in the Mediterranean recluse, the embolus is shorter and more curved than in the brown recluse, with a pointed tip (Fig. 2.8, top right). The palp may need to be rotated under the microscope to match the image in this figure. Similarly, the species of females are often difficult to determine. To do so, the reproductive organs must first be dissected from the abdomen and the fat tissue cleaned away. This is a very delicate operation involving a high-magnification microscope and fine dissecting forceps. The brown recluse female reproductive organs consist of a thin, sclerotized (hardened) ridge with many bumps (Fig. 2.8, bottom left). The desert recluse female reproductive organs look very much like those of the brown recluse, but typically have only one central bump (Fig. 2.8, bottom center). The Mediterranean recluse is much different and easier to discern because it has a sclerotized ridge on the top parts of its reproductive organs (Fig. 2.8, bottom right).

IDENTIFICATION

Fig. 2.9. Recluse spiders have uncate chelicerae, with secondary projections forming a pincer-like arrangement. Most spiders have saber-like fangs, like the wolf spider at right.

One other feature of potential interest to an arachnologist is the case where a badly smashed specimen is submitted for identification. Recluse spiders have a fang orientation called “uncate,” where the fang is short and a little spike projects off the chelicera to form a pincer-like arrangement (Fig. 2.9, left). Recluse spiders are not the only uncate spiders in the world (for example, cellar spiders and crevice weaving spiders also have this feature) but most spiders have saber-like fangs (Fig. 2.9, right). So if an arachnologist has the smashed remains of a spider and the only remaining structure left intact is a chelicera with a saber-like fang, then it can be determined that it is not a recluse spider.

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MISIDENTIFICATION

Misidentification is a common, recurring problem in areas of North America that do not have populations of brown recluse spiders (on distribution, see Chapter 5). Because this spider has gained such wide notoriety outside of its native range, laypeople who fi nd a spider often feel certain of the identification: “I have a spider here that looks just like the pictures I found of brown recluse spiders,” so it must be a brown recluse. Authority figures (such as physicians, pest control technicians, public health officials, and even entomologists) in regions where recluse spiders are not indigenous are sometimes assumed to be qualified to offer an accurate assessment, yet they too often misidentify harmless, common local spiders as brown recluses. Arachnologists in nonindigenous regions have received beetles, assassin bugs, camel spiders, and pseudoscorpions from the public as potential brown recluse spiders. In reality, 30 seconds of training on brown recluse spider identification would allow the submitters of these creatures to immediately know that the spiders aren’t recluses. In the Midwest, on the other hand, brown recluse spiders are so common and are seen so often that both authorities and the nonarachnological public are very proficient at identifying recluse spiders simply because they see them all the time. In 2005, the results of a five-year study based on an Internet request to send in any spider perceived to be a brown recluse spider from the United States were published in the Journal of Medical Entomology. Although indigenous brown recluse populations have been verified in only seventeen American states, specimens were submitted from forty-nine. Of the nearly eighteen hundred specimens sent in, members of the general public mailed in 158 different spider species from 88 distinct genera and 39 families of spiders. In North America there are only 68 families of spiders and 21

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most of the families not represented in this study are tiny, found only in remote, unpopulated habitats like the desert or high mountains, or in habitats where only arachnologists purposely searching for them would locate them. In short, virtually every medium- to large-sized brown spider associated with American homes was submitted as a potential brown recluse. Many of these misidentifications were due to people mistaking darkened patterns on the cephalothorax (Fig. 3.1) as the violin pattern of the brown recluse spider even though the resemblance was at times dubious.

Distinguishing Features of Recluse Spiders A brown recluse spider is very easy to identify from the features described in the previous chapter—if it is indeed a brown recluse. For people with average or better eyesight, three distinct spots on the front of the body should be visible, which correspond to the three pairs of eyes. Those

Fig. 3.1. Patterns on spider carapaces that are mistaken for violin markings. Top row from left to right: pirate spider, Mimetus hesperus (Mimetidae), cellar spider, Psilochorus papago (Pholcidae), Titiotus sp. (Tengellidae). Bottom row from left to right: male crevice weaver, Kukulcania utahana (Filistatidae), male pantropical huntsman spider, Heteropoda venatoria (Sparassidae), flatmesh weaver, Oecobius navus (Oecobiidae).

MISIDENTIFICATION

with very good eyesight might even be able to see the six individual eyes. Once one becomes familiar with the eye and violin patterns, it is extremely easy to identify a brown recluse spider correctly. Worldwide, recluse spiders are fairly uniform in coloration and the information presented here can be used for spider identification outside North America, though several species in South Africa have dark spots on the abdomen and cephalothorax (see Fig. 5.4).

Legs The legs of North American Loxosceles spiders are uniformly colored. In the immatures, the legs are almost all the same tan color. In some of the mature specimens, the front pair of legs may be a darker orange color than the other three pairs of legs, but each individual leg will be monochromatic. There will never be stripes, rings or spots on brown recluse spider legs (Fig. 3.2). Also, recluse legs are rarely dark brown except about two days before they molt (see Fig 4.13). Recluse spiders also have thin legs. If a spider has robust legs, then it is not a Loxosceles spider (Fig. 3.2). All Loxosceles spiders have fine hairs covering their legs (Fig. 3.3). Many spiders have very conspicuous spines arranged along their legs, which may be difficult to see in some specimens because they are on the underside. However, other spiders have spines on all surfaces that are easy to see.

Fig. 3.2 . Brown recluse legs are uniformly colored and thin (left) whereas spiders with stripes or spots on their relatively thicker legs are not brown recluses (right). The spider on the right is a funnel-weaver, Agelenopsis aperta.

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Fig. 3.3. Recluse spiders have fine hairs on their legs (left) whereas a spider with conspicuous spines (right) is not a brown recluse. The spider on the right is a pirate spider, Mimetus hesperus.

Abdomen The abdomen of the brown recluse is oval-shaped if the specimen is well fed, and is covered with fine hairs. As already mentioned, it is uniformly colored and the color can vary depending on what it has eaten (Fig. 2.6). A North American spider with multiple colors on the abdomen, either the topside or the belly, is not a recluse spider (Figs. 3.2 right, 3.3 right).

Size Loxosceles spiders are medium-sized. The largest brown recluse spiders are about 10 mm (3/8 in) in body length—the dimension by which arachnologists measure spiders because there is too much variation in the length of legs among individuals. The Chilean recluse, L. laeta (pronounced “leeta”), is larger and females may reach 13 mm (1/2 in) if very well fed. Therefore, if a spider’s body length is greater than 1/2 in, then it is too large to be a Loxosceles spider.

MISIDENTIFICATION

Fig. 3.4 . The spotty, unstructured webbing of brown recluse silk on a window. During the day, the spider hides in the hole at lower right.

Webs Although recluse spiders do use silk to line a retreat where they stay when they are inactive and also may extend their silk outward to act as trip lines, for the most part recluses do not make an obvious web out in the open where it can be seen. Many non-Loxosceles spiders in gardens or basements build large webs to catch prey. A spider in a web is very unlikely to be a brown recluse unless it has become prey for another spider. Recluses will, however, make a small web at the bottom of a doorjamb, under a windowsill (Fig. 3.4), or in some other retreat and sit and wait there for prey to fall onto the web.

Spiders Commonly Mistaken for Recluses The following listing gives an idea of the many common spiders that people claim to be, or fear might be brown recluse spiders. Many other species are also submitted, but less frequently—because they look very different from recluses, because they are geographically limited, and possibly most

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importantly, because they don’t find human structures to their liking so they don’t interact with us very often.

Crevice Weavers In the 2005 study mentioned above, crevice weaver spiders of the genus Kukulcania (family Filistatidae) were the most common specimens submitted as brown recluses. The representative nature of this finding is corroborated by many American arachnologists from the Southeast who are repeatedly presented with Kukulcania specimens that have been mistaken for brown recluses by the general public. This is not surprising because males of this genus share several features making this confusion possible: tan coloration, long legs, proportional dimensions of the cephalothorax to the abdomen, proportion of the leg thickness and length to the main body. There is even a little darkening around the eyes, which caused most people, including even a Georgia physician, a Virginia licensed nurse practitioner, and several pest control operators in the South to see a violin where none actually exists (Fig. 3.5, left). However, close inspection reveals eight eyes, all clumped on a little turret at the front of the cephalothorax (Fig. 3.1, bottom left). The female Kukulcania spiders are very different from the males; they are dark brown or black with a velvety appearance, have larger abdomens, and look like miniature tarantulas (Fig. 3.5, right). Nonetheless, females are often submitted for recluse verification. Also, some of the males and almost all of the mature Kukulcania females are too large to be recluse spiders.

Fig. 3.5. In the United States, spiders of the genus Kukulcania are the most common species submitted as brown recluses including the tan-colored male (left) because it has a pattern that some people perceive as a violin. Female Kukulcania spiders are velvety black or dark brown (right). The light color on the legs and posterior abdomen of the female is the light reflection of the camera flash. This species is K. utahana.

MISIDENTIFICATION

These spiders used to be known by the genus name Filistata, which is found in the older literature, but now Filistata is reserved for species in the Eastern Hemisphere. From Florida to Texas, Kukulcania hibernalis is the most common species and may be the only species found in this area. In the southwestern United States, K. utahana can be collected in southern California, K. arizonica is found from northern California southward extending into New Mexico, and K. geophila, a smaller species, lives in California’s Central Valley. Because this spider genus has not received any taxonomic attention since the original species descriptions in the early 20th century, there may be additional species to be named.

Spitting Spiders Spitting spiders (family Scytodidae) have the same pattern as recluses of six eyes in pairs, separated by gaps. However, spitting spiders often have many black spots on their cephalothorax, legs, and abdomen, (Fig. 3.6)

Fig. 3.6. Spitting spiders of the genus Scytodes are closely related to brown recluses and therefore have a similar eye pattern, but their body coloration looks nothing like that of a brown recluse. The bite of this spider is harmless. The specimen here is Scytodes atlacoya.

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unlike North American recluse spiders which have uniformly colored legs and abdomens. Spitting spiders can also be completely black. Additionally, spitting spiders have very unique, modified venom glands used in prey capture. Many spiders use silk emitted at the posterior end of their bodies to wrap and/or subdue the prey so it doesn’t escape and then use their venom sacs to inject venom to paralyze prey. In contrast, spitting spiders use modified venom glands to spit silk very rapidly in a zigzag pattern from their fangs to pin prey to the ground. Once the prey is secured, the spitting spider approaches and feeds. These modified venom glands are greatly enlarged and are located in the cephalothorax, so that in side view the cephalothorax of spitting spiders is markedly domed, whereas in recluse spiders it is relatively flat. Although spitting spiders are closely related to recluse spiders taxonomically, their bite is harmless.

Cellar Spiders Cellar spiders (family Pholcidae) are very long-legged and frequently make webs in basements and under the eaves of houses. They are also known as daddy longlegs spiders (not the same as daddy longlegs or granddaddy longlegs, which are in a different arachnid order, Opiliones). Many species of cellar spiders are found in the United States. The most common cellar spider misidentified as a brown recluse is a European immigrant, the long-bodied cellar spider, Pholcus phalangioides (Fig. 3.7, left). This spider is extremely common in many regions of the

Fig. 3.7. The long-bodied cellar spider, Pholcus phalangioides (left), is frequently mistaken for a brown recluse because of a dark pattern on the carapace (right).

MISIDENTIFICATION

United States, and is gray to tan in color with a few spots on an elongate abdomen. The confusion with Loxosceles spiders occurs because it has a darkened pattern on its cephalothorax (Fig. 3.7, right). On the other hand, these spiders have eight eyes clumped together in the front of the cephalothorax. With magnification, one should see a closely arranged group of three eyes on either side, with a small pair of eyes in front. In the western United States from the San Francisco Bay to southern California and east to New Mexico, another cellar spider from the Mediterranean region has become incredibly common. It is the marbled cellar spider, Holocnemus pluchei. It has a brown sternum on the cephalothorax and a brown stripe on the belly, colorations that are liable to be misidentified as the violin pattern of a Loxosceles spider. Additionally, the dorsal surface of the abdomen is marbled with browns, tans, and whites that should never be mistaken as markings of a recluse. Smaller cellar spiders, which are native American species, also have a dark violin-like pattern on the cephalothorax. They are in the genera Psilochorus (Fig. 3.1, top row, center) and Physocyclus. They also typically have spots on their abdomens. However, although these are native species, they do not often take up residence in homes so people do not encounter them frequently.

Wolf Spiders Wolf spiders (family Lycosidae) are all too commonly mistaken for brown recluse spiders. They range from very small (3 mm [1/8 in] body size) to very large (35 mm [1-1/2 in] body size). Four of their eyes are very large (two of them forward-facing on the front of the cephalothorax and visible with a hand lens in the larger species, Fig. 3.8, left) and they have very good vision. They often traipse through homes, and can see you coming at them with a shoe in your hand and make their getaway. Most wolf spiders are colored with dark browns, medium browns, tans, and some black (Fig. 3.8, right). Some have very conspicuous stripes on their cephalothorax or an elongated black diamond over the cardiac region on the front portion of the abdomen. Many have robust, dark brown legs with spines, which should readily eliminate them from consideration as brown recluses. Almost all wolf spiders are free-roving hunters and do not use silk except to line a burrow or other retreat or to cover an egg sac, though there is one aberrant, ancestral genus of wolf spiders, Sosippus, which actually makes a funnel web. These spiders are ubiquitous in most areas in the United States and are frequently found near water or at least moisture, although there are several desert species as well.

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Fig. 3.8. Wolf spiders have large “headlight” eyes with four smaller eyes below (left) and usually have stripes and other markings (right) that distinguish them from recluse spiders. This species is Hogna antelucana.

Funnel-weaver Spiders Funnel-weaver spiders (family Agelenidae) are also ubiquitous throughout North America. The most common are in the genus Agelenopsis (Fig. 3.2, right) and are some of the largest members of this family in North America, reaching up to 17 mm (3/4 in) in body length. They share many features with wolf spiders, notably their combination of brown and tan coloration, and are frequently mistaken as such even by entomologists who have some arachnological knowledge. Most of the agelenid spiders build a funnel web, a large, flat, horizontal sheet of thickly woven silk looking like a trampoline. The sheet constricts backward, typically toward a hole such as an opening in bricks or under wood, and in natural settings, rodent burrows or gaps under mats of vegetation. These spiders are basically harmless and should never be confused with the highly dangerous Australian funnelweb spiders which are potentially deadly. Despite the name similarity, the Australian funnel spiders are mygalomorphs in the family Hexathelidae and not even closely related to the Agelenidae, which are araneomorphs. The most widespread agelenid species in eastern and central North America are A. pennsylvanica and A. naevia; in the western United States, A. aperta and A. potteri are the most common species encountered. All of these species look fairly similar, and are often mistaken for brown recluses. However, unlike recluses, they have a distinct pattern on the dorsal abdominal surface, typically longitudinal stripes on the cephalothorax with very long spinnerets trailing the abdomen visible in dorsal view.

MISIDENTIFICATION

Another complex of agelenid spiders is frequently found in homes, barns and outbuildings. However, here is another example of a name change instigated by taxonomic research. Two large spiders previously considered to be in the genus Tegenaria have now been transferred to a new genus, Eratigena, an anagram of Tegenaria: the hobo spider, E. agrestis, and the giant house spider, E. atrica (the latter of which used to be known also as T. duellica and T. gigantea.) The hobo spider is covered more extensively in Chapter 9, as it has been implicated in skin lesions (although the reality of its venom having toxic effect on humans is seriously questioned). The giant house spider is indeed large, with a body about 12 to 18 mm long (1/2 in to 3/4 in) but its leg span is quite impressive, being 35 to 60 mm (1-1/2 in to 2-1/4 in). Both the hobo spider and the giant house spider are native to Europe and probably entered North America through the port of Seattle, where they were first found on this continent. The giant house spider lives almost exclusively along the Pacific coast west of the Cascades range from British Columbia to Oregon. The hobo spider exists in this same area but has spread east to Montana, Wyoming, Colorado, and northern Utah. A very common agelenid species in North America is the barn funnelweaver, belonging to the genus Tegenaria and known as T. domestica (Fig. 3.9). It is a smallish spider about 5 to 9 mm (about 3/8 in) in body

Fig. 3.9. The barn funnel-weaver, Tegenaria domestica, is a common spider throughout the world.

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length, having the typical brown coloration of agelenids with rings of dark brown on lighter background on the legs. This European immigrant is found throughout North America and, in fact, on many continents, having been moved around the world for centuries by human commerce. In the western United States, spiders of the genus Hololena are also submitted as recluses. These are small to medium-sized spiders and again, have the typical agelenid color scheme.

Orb-weavers It is somewhat difficult to understand why so many orb-weaving spiders (family Araneidae) are submitted as brown recluse spiders. They make large spiral webs that are characteristic of the typical Halloween decoration (Fig. 3.10, left). They have large, globular abdomens unlike anything one would see in a brown recluse and almost always have conspicuous, contrasting body markings on the dorsal abdomen, the belly, and oftentimes both (Fig. 3.10, right). They also are usually adorned with large, conspicuous leg spines. One reason for misidentifications may be that orb-weavers have widely separated eyes with two pairs so closely arranged that without a microscope it may seem as if there are only six eyes instead

Fig. 3.10. A typical orb-weaver web and an orb-weaver spider, Neoscona sp., with multiple abdomen colorations and conspicuous leg spines.

MISIDENTIFICATION

of eight. But mostly it is because these are large spiders and are perceived as dangerous; therefore, the inexperienced nonarachnologist supposes that they must be brown recluses. Orb-weavers have an annual life cycle in which they overwinter in egg sacs, emerge in the spring, and undergo tremendous growth so that the females in particular can greatly increase in size by the end of the summer before laying an egg sac and dying. If this sounds vaguely familiar, it may be because the spider character in E. B. White’s Charlotte’s Web is an orbweaver. That is why she can’t make it home from the fair with Wilbur the pig—she is at the end of her natural life cycle. Orb-weavers are very common throughout North America and exist in quite a variety of shapes and sizes including some with large and imposing abdominal spines, such as Micrathena and Gasteracantha. They are typically found in webs or tucked away in hiding spots. It is very rare to find an orbweaver crawling around off its web. Their bodies and legs are not designed for this mode of locomotion and they are clumsy when they adopt it.

Comb-footed Spiders The comb-footed spider (family Theridiidae) is a web-builder, typically making a haphazard tangle of silk as a capture net. Like orb-weavers, these spiders have large globular bodies, which makes it difficult for them to move once off their webs. The black widows are comb-footed spiders, which may give a better idea of the general body shape although there is variety within the family. The comb-footed spider most often submitted as a brown recluse is the common house spider, Parasteatoda tepidariorum, another European immigrant that is very common in homes in North America. The abdomen of the female is mottled with brown, tan, and white, while the male has a smaller abdomen with a less recognizable color pattern. Both sexes are submitted as Loxosceles spiders. Another very commonly misidentified spider is the false black widow, Steatoda grossa (Fig. 3.11) which is very prevalent on the western North American coast, in Colorado, and in the southeastern United States. As the name implies, the female looks very much like a black widow, being shiny dark brown overall and having a globular abdomen. The male retains the coloration of the juvenile and has tan spots on its abdomen with lighter tan or orangish legs. Despite the lack of credible resemblance to a brown recluse, both sexes of this species are routinely suspected of being the infamous Loxosceles spider.

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Fig. 3.11. Female false black widows, Steatoda grossa, are submitted by homeowners although the spiders look much more like black widows than brown recluses.

Males of the western black widow, Latrodectus hesperus, likewise retain the juvenile coloration, in their case a series of white abdominal stripes on a tannish body. Despite this very nonrecluse appearance, they have on rare occasions been submitted as potential recluse spiders.

Woodlouse Spider One of the most common spider species submitted as a brown recluse from throughout much of the United States is the woodlouse spider, Dysdera crocata (family Dysderidae, Fig. 3.12), which is yet another European immigrant and common worldwide. It has a very characteristic and almost diagnostic coloration: a cephalothorax of a dark cinnamon color with the abdomen varying from monochromatic tan to gray. It has six very small eyes located in a bunch on the front of the cephalothorax, and typically only visible with magnification. However, the woodlouse spider has very large fangs, which it is not afraid to unfurl in self-defense. Despite the lack of a violin marking, different coloration, and a different eye pattern, people have thought these spiders to be brown recluses, in part because they

MISIDENTIFICATION

Fig. 3.12 . The woodlouse spider, Dysdera crocata, has six eyes but they are in triplets, not pairs, and the spider has long fangs.

have large fangs and therefore they “must” be dangerous. Nonetheless, even with their large fangs and their menacing defensive behavior, woodlouse spider bites are basically harmless (see Chapter 9).

Titiotus Spiders This genus of spiders (family Tengellidae) causes quite a number of misidentifications in California and for good reason. They look very similar to brown recluses in coloration, body proportions, leg length, and even the way they position their legs before they move (Fig. 3.13). However, they have eight widely spaced eyes, which may be visible with a magnifying glass or hand lens (Fig. 3.1, top row, right). What the reader may find amazing is that although this is a medium-sized spider often collected in Californian homes, almost nothing is known about them. Most of the Titiotus species were not described until 2005. Now there are sixteen species, all found within California, often in areas of dense human population. They are most common from the northernmost portions of the state to the southern portions just north of the mountains near the Los Angeles Basin. They are often found in redwood forests and romp through cabins in the woods.

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Fig. 3.13. Spiders of the genus Titiotus strongly resemble brown recluses and are only found in California.

In one example of how misleadingly Titiotus resembles Loxosceles, a journalist from Redding, California (in Shasta County), challenged his readers to submit spiders thought to be recluses. Over 75% the spiders submitted as proof of brown recluses in the area, turned out to be Titiotus spiders (and none of the rest were brown recluses). These submitted specimens contributed greatly to the original description of the new species Titiotus shasta.

Huntsman Spiders Huntsman spiders (family Sparassidae) are medium- to large-sized creatures, which occasionally are submitted as brown recluses although they are geographically limited in their distribution. Their legs are rotated slightly to the side, which gives them somewhat of a crablike appearance. The most common species is the pantropical huntsman spider, Heteropoda venatoria, which is a huge spider (body length 20 mm [3/4 in] and leg span up to 85 mm [3-1/2 in]) and frightens people as it cavorts around homes. It is very well established in Hawaii, Florida, and a few other Gulf Coast areas as well as throughout

MISIDENTIFICATION

many tropical and subtropical regions of the world, including Taiwan, Hong Kong, Ecuador, Uganda, and South Africa. In Hawaii, it is known as the cane spider. Because large spiders are often equated with danger, this harmless spider is thought to be a recluse. Misidentification also occurs because the male has white, tan, and brown markings including a triangular marking that sometimes is perceived to be a violin (Fig. 3.1, bottom center). The female is almost completely dark brown with some accents of white and tan. However, one characteristic may help Floridians and Hawaiians identify this spider more readily: both sexes have a white “moustache” under their eyes. In Arizona and California, members of the huntsman spider genus Olios are sometimes considered to be recluses. These spiders are light tan in color. In one species, O. giganteus, a series of black lines on the front portion of the dorsal abdomen looks like a tuning fork; this pattern is mistaken for the violin.

Fishing and Nursery-web Spiders Spiders in this family (Pisauridae) are occasionally submitted for identification. The fishing spiders (genus Dolomedes) are typically found near water and hunt by dipping their front legs into a pond, lake, or other still body of water. As a fish or possibly an aquatic insect disturbs the water surface, the spider detects the ripples and catches its prey. In so doing, the fishing spiders rely on the water surface in the same way that a web-building spider uses the vibrations of its silk filaments to detect prey. The most common fishing spider mistaken for a recluse is D. tenebrosus, which can be quite large (body length 25 mm [1 in], leg span up to 85 mm [3-1/2 in]). Most fishing spiders live east of the Mississippi River, with D. tenebrosus being found from Florida to Maine. Nursery-web spiders (genus Pisaurina) have vague patterns on their cephalothorax and abdomen that are perceived to be violin markings. Both P. mira and P. brevipes are submitted; P. mira more so because it has a much wider distribution in the eastern United States.

Sac Spiders Sac spiders (families Eutichuridae and Trachelidae) are rather plain and unremarkable in appearance. The most common sac spider mistaken for a recluse is the yellow sac spider (genus Cheiracanthium) despite the fact it has eight widely spread eyes and no violin marking, and is yellowish instead of brown (Fig. 3.14, top). Trachelas species also have eight widely spaced eyes, located on a dark cinnamon–colored cephalothorax like the woodlouse spider—though the eye pattern is very different—and are likewise commonly misidentified.

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Fig. 3.14. Sac spiders of the genus Cheiracanthium (top) are frequently mistaken for brown recluse spiders even though they have eight widely spaced eyes in two almost straight rows and no violin marking. The marking on the dorsal surface of the abdomen of the parson spider, Herpyllus propinquus (bottom) is mistaken for a violin pattern of a brown recluse spider.

Ground Spiders Ground spiders (belonging to a variety of genera in the family Gnaphosidae) are typically undistinguished-looking brown creatures, although some are conspicuously colored with white and black. Many of these monochromatic ground spiders are submitted as recluses. Parson spiders have a tan or copper elongate geometric marking on the front portion of the dorsal abdomen over the cardiac region, which is mistaken as a recluse violin marking (Fig. 3.14, bottom). There are two widespread species of parson spiders: Herpyllus ecclesiasticus throughout the eastern half, and H. propinquus throughout the western half, of the United States.

4

LIFE HISTORY AND BIOLOGY

The life history characteristics described here encompass aspects such as mating, molting, egg sac production, and fecundity, among other biological traits of the brown recluse. Much of this work was done many years ago after it was determined that the brown recluse was a medically important spider and its life history became a matter of significance. Two papers, both written in the 1960s (Hite et al. 1966 and Horner and Stewart 1967, reporting from Arkansas and Texas respectively), provided information that still forms the basis for this account, together with later corroboration and supplementation by other researchers, including unpublished data from the author. Spiders are poikilotherms; they cannot regulate their body temperature. Their life history characteristics are therefore greatly influenced by ambient temperature. Hite and her colleagues did their work in a laboratory where they maintained temperature between 21 °C and 35 °C (70 °F and 95 °F). Horner and Stewart, although working in a laboratory at similar temperatures during most of the year, exposed their colonies to lower, more natural temperatures in the winter. As a result, the data from the report of Hite and colleagues indicate life spans of shorter duration and other traits which may differ from Horner and Stewart’s study because in the latter, the spiders spent a lot of time inactive in cold weather and thus their metabolic processes were slowed down. Additionally, growth is related to food intake, and unless the spiders are fed as often as they would normally catch prey there is no way to know if growth in a lab environment is really mimicking what happens in nature. Finally, in the laboratory, spiders are kept in small vials, which limits their movement. In nature and free to roam, they expend more energy moving about. Therefore, there is no way to know for sure whether the laboratory data overestimate 39

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or underestimate variables such as life span, growth rate, and energy expenditures in the field situation. Nonetheless, because much of this information cannot be obtained from the field, this is the best available data and does give relative values approximating what we expect to see in natural conditions.

Growth and Life Span Although brown recluses have the same metabolic rate as other spiders, they can slow down their heart rate during periods of inactivity, allowing them to live much longer than the typical spider. In experiments in the lab, male brown recluses lived an average of 897 days and females averaged 794 days, with 25% of the females surviving over 1,000 days including one lasting almost 5 years. When exposed to winter temperatures, all brown recluses in the study lived for more than 4 years. In another study, when fed weekly at first and then sporadically every 3 to 10 months, the Chilean recluse, L. laeta , required over 2 years to mature and then lived almost 5 years after maturation. Recluse spiders are well known for living a long time without eating. This is one of the aspects frequently mentioned when people discuss the spider’s potential for being transported around the country and becoming established elsewhere (which in fact does not happen often). In one study, brown recluses survived longer when starved if maintained at lower temperatures, and L. laeta was able to live up to fourteen months on average without food. Again, this is not a normal situation: in nature, most spiders would die much sooner because they would be more active and use up their energy stores.

Mating Mating for the brown recluse is a simple affair, and it is very easy for researchers to induce. Typically, just placing a male in an arena with a virgin female is enough to get the process started. The male approaches the female and when he senses her presence, he stops walking around the arena (Fig. 4.1). He often plucks at her web, sending vibrations to alert her that he is a suitor and not prey. Then he faces the female; moves his first pair of legs over her, stroking her front legs, in an apparent embrace (Fig. 4.2); and vibrates his legs while draping them over the female. Both spiders vibrate their palps almost continuously, especially when they touch each other (Fig. 4.3). The vibration actually produces a sound called stridulation,

Fig. 4.1. The female brown recluse spider (left) draws back her legs as the male (right) approaches and signals with his front legs.

Fig. 4.2 . The male (right) drapes his legs over the female (left) and vibrates them.

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Fig. 4.3. Both spiders vibrate their palps and may vibrate their abdomens. This produces a sound called “stridulation” which signals receptivity and species identity to each participant.

Fig. 4.4. The female (left) raises her cephalothorax and the male slides underneath to insert his palp into her reproductive opening. The male’s palp can be seen just above the asterisk underneath the tangle of legs.

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caused by the spider moving a little peg or pick on the palp over a series of ridges on the chelicera and making a noise similar to running a stick over an old-fashioned washboard. Either partner may give a single violent shake to the web and/or pulse their abdomen. The female then moves her front legs upward and backward which causes the front part of her body to angle up. The male then moves under the female and inserts his palps into the female’s reproductive opening (Fig. 4.4). Typically both palps are inserted simultaneously. Initial insertions last 20 to 30 seconds with subsequent insertions being shorter. The mating terminates when one of the spiders abruptly runs away. Horner and Stewart mention only one male who did not survive in forty mating events in their study. This involved an aggressive male and an unreceptive female that killed him. In a 2009 research paper by Fischer and colleagues, much more information was provided in regard to the mating behavior of a South American recluse spider, L. intermedia. Although there are differences among the several Loxosceles species whose mating behaviors have been investigated, many of the mating behaviors of this South American species will probably be very similar to those of the North American brown recluse. Both species stridulate, but males of L. intermedia always stridulate whether or not the female does so, whereas female stridulation is instigated by male contact. The sound produced by this rubbing differs for the two sexes. The male stridulates more often (six times a second to the female’s twice), and his stridulations are shorter (one-eighth of a second to the female’s quarter of a second) and have a higher amplitude. In L. intermedia, only the female vibrates her abdomen whereas in the brown recluse, both species do so. When the L. intermedia female stops her abdominal vibrations, this is a signal to the male that she is receptive to his “manly charms” and will accept him as a mate. She then rises up so the male can insert his palps into her reproductive opening. Chemical cues are also important in L. intermedia spiders. If live spiders are picked up with forceps and dipped into acetone, chemical odors are removed from their bodies. (They are not very happy about this chemical bath but they survive, recover in a few minutes and act normally, and it does not affect longevity.) Acetone-washed males are rejected as mates and killed by females more often than unwashed males, and males do not court acetone-washed females as frequently as they do unwashed females. The lack of response to solvent-washed animals indicates that chemical communication is being used in species recognition. In the study by Hite and colleagues, most matings by brown recluse spiders happened in June and July but the earliest occurred in February and

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the latest in October. However, the brown recluses observed by Horner and Stewart and maintained at more natural temperature cycles mated only from June to September, which is probably a more realistic mating season. If matings are needed for research, a rather successful procedure is to place a female in a vial for a few days or weeks so she can lay down silk and chemical odors. Then, when matings are desired, remove the lid of the vial and place the open vial, on its side, in a plastic storage-type container such as a sweater box or shoe box. Add a male to the container and cover it with a tight-fitting lid. The silk and chemical odors that the female has deposited on the inside of the vial will be used by the male for identifying her as a potential mate, and because the vial is on its side, the male will be able to walk into it and approach the female. Adult-sized brown recluses typically cannot climb up plastic, so having the vial in the plastic container should prevent escapes (the tight-fitting lid is used in case the spiders do climb up the walls). Let the spiders stay together for a few days and then remove the male. It is important to do this during the summer months when matings are common because the longer daylight may be critical for female receptivity. It is also important to make sure both spiders are well fed prior to placing them together to minimize the chances of cannibalization. In addition, if the female has already mated, she may have no interest in the male so it is important to use virgin females.

Egg Sacs In the first stage of making an egg sac, the female brown recluse spider lays down very fine white silk produced from her spinnerets by rhythmically moving her abdomen over the same spot, usually on a vertical surface, rotating her position slightly with each pass until she has produced a circular patch of silk about 17 mm in diameter. This process usually takes an hour. The female then positions herself over the silk, contracts her abdomen, and extrudes eggs as a gooey mass from the reproductive opening on the anterior portion of the underside of her abdomen. This process takes about five minutes. At this point, the eggs are moist and cling together in a wet bundle. The female rests for about fifteen minutes and then may place more eggs onto the existing ones, taking five minutes to do so. She may rest again and extrude still more eggs into the pile. After the mother spider is finished laying, she covers the egg sac with very fine white silk similar to the underside of the sac and with the same movements

LIFE HISTORY AND BIOLOGY

as before. After the eggs are secured with this fine silk, the mother produces a looser silk to cover the outer surface of the egg sac. For all spiders, one of the functions of this silk is to help repel insects such as wasps or flies looking to parasitize the eggs. This entire process of making the egg sac and laying eggs from start to finish requires about six hours. When the female is done, the back of the 17 mm–diameter sac is flat against the substrate and the outer surface is domed at about 3.7 mm in height. The egg sac is described as being lenticular in shape—similar in shape to a lentil, round in outline and flattened in thickness. Inside the sac, the eggs dry out and separate and then become free from each other, rolling around like ball bearings. The egg sac is left attached to the substrate and the female typically positions herself over the sac to defend it from possible parasites (Fig. 4.5). A brown recluse is a medium-sized spider and the average egg sac contains 50 eggs with a recorded maximum of 91. Females average 2.7 egg sacs in a lifetime (range = 1 to 5) with 20 to 28 days interval between sacs. Females lay their first egg sacs about 12 days after mating, and in the lab,

Fig. 4.5. Female brown recluse guarding an egg sac.

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Number of spiders

70 60 50 40 30 20 10 0 1

2

3

4

5

6

Number of egg sacs per female per lifetime

Fig. 4.6. The number of egg sacs produced by female South American recluse spiders, Loxosceles intermedia, in a lifetime. Data were reconfigured from Fischer and VasconcellosNeto 2005.

they have laid repeatedly without additional matings; however, the first egg sac had the greatest number of eggs and subsequent sacs had progressively fewer. This may be a result induced by captivity, whereas in nature, recluse spiders may mate after they lay each sac and then may be able to lay equivalent numbers of eggs with successive sacs. For comparison, with the South American recluse L. intermedia, in the lab the average number of spiderlings emerging from a sac was 20 (range = 1 to 110). Females experiencing one mating in the lab laid 1 to 6 egg sacs with the fifth and sixth egg sacs being infertile (Fig. 4.6). The average time between egg sacs was 68 days (range 18 to 136). In addition, females produced more eggs as a function of size and mating time—the bigger the female and the more time she spent mating, the more eggs she laid. Another South American recluse, L. gaucho, laid egg sacs an average of 20 days after mating (range = 10 to 31) and averaged 61 spiderlings per egg sac (range = 25 to 117). As with the brown recluse, the number of L. gaucho spiderlings per sac decreased with successive egg sac number. Recluse spiders do not lay many eggs in comparison to other spiders. For example, western black widow spiders average over 250 eggs per sac and can lay up to 14 sacs per lifetime. Tarantulas of the genus Aphonopelma and many species of orb-weaving spiders can lay up to 1,000 eggs per sac. Very small spiders (less than 1 mm in body length) lay only one egg amounting to 40% of their body mass.

80 Horner data

70

Hite data

60 50 40 30 20 10

ly Au gu st Se pt em be r O ct ob er N ov em be De r ce m be r

Ju

ne Ju

ay M

ril Ap

ua br

nu

ar Fe

Ja

ry M ar ch

0

y

Number of brown recluse egg sacs

LIFE HISTORY AND BIOLOGY

Month

Fig. 4.7. Brown recluse spider egg sac production by month in captivity. Data were reconfigured from Hite et al. 1966 and Horner and Stewart 1967.

Brown recluse egg sacs were produced almost exclusively during the summer months. Hite et al. collected egg sacs in the laboratory from February to September, with only one sac in February and March and two in April, whereas Horner and Stewart, with their more natural temperature cycle, observed egg sacs only from May to September (Fig. 4.7). The South American recluse, L. gaucho, laid 66% of its egg sacs in the summer (November to April in the Southern Hemisphere).

Development Inside the Egg Sac Once the brown recluse spider eggs dry out and separate from each other, they are pearly white to yellowish in color, perfectly round and 1.2 mm in diameter (Fig 4.8, left). Hite and her colleagues have shown that after the egg sac is laid, the egg requires about 13-1/2 days before the spiderling hatches although warmer temperatures lead to quicker developmental times. The initially round egg takes on an oblong shape as the spiderling pushes on the outer surface of the egg (the chorion). Eventually, the chorion ruptures, shrinks back like a sleeping bag when someone wriggles out of it, and stays at the posterior end of the spiderling (Fig 4.8, right) before it is cast off. Although some of the rudimentarily developed features like

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Fig. 4.8. Eggs of the brown recluse spider (left); the lines at top are 1 mm marks on a metric ruler. At right, a recently hatched embryo where the rudimentary legs are evident as well as the shed skin of the egg which is crumpled at the end of its body. The two bright spots on each egg and multiple light spots on the embryo are reflections from the photographic illuminators.

the legs and mouthparts are recognizable, the spiderling is covered by a thin veil of tissue and is in the first post-embryo stage. At this point, the spiderlings are still completely encased within the egg sac. About 3-1/2 days later, the spiderling again pushes from within, frees itself from the veil, and enters the second post-embryo stage. It is somewhat helpless, typically white in color, with thick, short legs unlike what it will eventually develop once outside the sac, and looks similar to a little piece of white gummi candy. Because most arachnologists work with the emerged spiders and never see the spiderlings inside the sac, they do not differentiate between the two post-embryonic stages. Instead, they merely lump these two together and refer to them as the first instar, the stage between hatching and the first actual molt. The second post-embryo stage lasts about 13 days, and toward the end, the spiderling’s legs darken. When this happens, the egg sac changes from bright white to a darkened shade indicating an imminent emergence. The spiderlings undergo their first true molt inside the egg sac (as do all other spiders) and stays there for about 3 days before emerging from the

LIFE HISTORY AND BIOLOGY

Fig. 4.9. Brown recluse spider mother and spiderlings.

sac. Brown recluse spiderlings can emerge without their mother’s assistance; however, if the mother is still guarding the sac, she helps her offspring by pulling back the silk so they can emerge more easily (Fig. 4.9). (In comparison, in some spiders, such as wolf and yellow sac spiders, the mother has to rip a hole in the sac—otherwise the spiderlings can’t emerge and would die inside the sac). The second instar brown recluse spiderlings look very much like small replicas of the adults except that they lack the darkly pigmented violin marking. On average, it requires 32-1/2 days from the time a brown recluse egg sac is laid for spiderlings to emerge from it. Four egg sacs taken from the Hite study, one laid in each month from April to July, show the effects of temperature on spiderling development (Fig. 4.10). The sac from April, with its cooler temperatures, took 39 days from laying to emergence while the sac from July took 25 days. In comparison, incubation from egg laying to emergence for the South American recluse, L. intermedia, was 50 days (range = 30 to 106 days) again with temperature (and time of year) playing a role. The average viability of eggs for females mated once in the lab was 70% (range = 4%

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CHAPTER 4 40 Cumulative days for event

50

35

5 April

30

1 May 2 June

25

3 July

20 15 10 5 0 Eggs laid

Eggs hatched

Molted inside sac

Emerged

Fig. 4.10. Egg sac development times. Data were reconfigured from Hite et al. 1966.

to 100%) and for field-collected females of unknown mating history, 81% (range 1% to 100%).

Development Outside the Egg Sac Species of spiders that eventually attain a large size when mature molt more times than spiders that mature at a smaller size. Because recluses are medium-sized spiders, they go through an intermediate number of molts— about eight—before reaching maturity. Because most of the exoskeleton is hardened over most of the body, only the abdomen grows during a particular instar while the rest of the body parts remain static. This fact is useful because one can measure a feature such as the cephalothorax width to get a good indication of which instar the spider might be. Figure 4.11 shows the range of brown recluse spider cephalothorax widths taken at its greatest size in each instar. Besides temperature, development varies greatly depending upon the amount of food an individual spider obtains. In a captivity study, it required an average of 335 days from egg to maturity for the brown recluse. For the South American recluse, L. gaucho, whose spiderlings don’t start feeding until the fifth to eighth day after emergence, both sexes matured around 485 days on average, they did so in the seventh and eighth instars, and they averaged 2 to 3 months in each instar when fed weekly. Insects have a specific number of developmental stages, depending on the species, before they molt to maturity. Spiders, however, are more flexible, being able to mature after a varying number of molts (Fig. 4.12). When

Post-molt cephalothorax width

3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 1st

2nd

3rd

4th

5th

6th

7th

8th

Adult

Instar

Fig. 4.11. Cephalothorax widths (in millimeters) of brown recluses by instar with the mean indicated by the dot and the range of sizes indicated by the vertical bar. Data were reconfigured from Hite et al. 1966.

Fig. 4.12. Male brown recluse spiders of differing sizes. The male on the left (body length = 8.5 mm) was captured as a mature spider in a home in Lenexa, Kansas. The male on the right (body length = 6 mm) is also mature, but was reared in captivity from an egg sac with minimal and sporadic feeding.

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food is plentiful, spiders gain weight quickly and mature at a later instar (and therefore, at a bigger size) because size gives a spider advantage. A larger male can more easily chase off rival males and also be a more attractive mate for a female he is wooing; a larger female can lay more eggs over her lifetime. However, if food is scarce, a spider can mature at an earlier instar. Although he or she will be smaller, in conditions of food scarcity it is a better strategy to mature earlier and be smaller so that the spider can still reproduce than to take the chance of trying to get bigger at a later instar but risk dying from starvation as an immature spider and never reproducing.

Molting Spiders are arthropods, having a rigid exoskeleton to which internal muscles attach that allow movement. Because of this hard exterior, there are limits to how large an individual spider can grow before it has reached the maximum that an exoskeleton of a particular size will permit. In order to grow, a spider has to molt, shedding its exoskeleton as it moves from one instar to the next one. Molting is a potentially dangerous activity for any spider. Faulty molting is a common nonpredational cause of death: when spiders cannot pull their legs free of their old exoskeleton, they die still partially encased in it. As a brown recluse spider acquires sufficient food to grow to the next instar, great physiological changes occur inside the body. The spider produces another exoskeleton under the old skin. About 7 to 9 days before the molt occurs, the spider stops eating, ignoring food offered to it. About 2 days before the molt, the legs become very dark because the new leg hairs have become visible under the old, overlying exoskeleton (Fig. 4.13). The spider still moves around and no physical difference is noticed from its nonmolting period. The positioning of a brown recluse’s legs will indicate if it is getting ready to molt. During regular times when the spider is not molting, the characteristic stance of the brown recluse spider at rest is with the three front pairs of legs forward, all relatively close to each other, and the last pair pointing almost directly backward, with the legs held in a slanted posture, bent at the joints (Fig. 1.1). The spider may have its cephalothorax pointing in no particular direction and the anterior portion of the abdomen covers the posterior portion of the cephalothorax. In contrast, when a brown recluse is about to molt, several hours prior to the event it takes a position with its cephalothorax facing upward and its legs held somewhat apart and more evenly spaced (Fig. 4.14, left). The

Fig. 4.13. A brown recluse preparing to molt as is evident from the darkened legs.

Fig. 4.14. An hour or two before a brown recluse molts, it takes up a characteristic splaylegged position (left). The molting process starts when the abdomen is contracted, increasing the pressure in the cephalothorax which pops the carapace off the old exoskeleton (right).

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legs are straighter than in a normal resting position and held flatter against the surface where the spider is positioned. Then the spider straightens its legs still more and holds them outward, slightly farther apart rather than bunched together. The hind legs are not held so far behind the spider but more out to the side. In many respects, the positioning of the brown recluse spider, when it is getting ready to molt, looks like an asterisk with lots of space between legs. It positions itself this way because it is much easier during molting to remove its long legs from the old exoskeleton if the legs are straightened. The spider takes up the molting position one to two hours before the active molting process and remains motionless. If the spider is positioned on a vertical surface, the abdomen “drops” down from its position, looking very swollen and pendulous. The abdomen no longer overhangs the cephalothorax; the pedicel (the little conduit connecting the cephalothorax to the abdomen which is normally covered) can be seen very clearly. The spider can also molt on the underside of a horizontal surface if it can hang down. In either orientation, there are claws at the end of its legs, which typically grab onto the silk of its web for anchoring and allows the brown recluse to pull itself out of its old exoskeleton. Eventually, the spider contracts its abdomen and the abdominal fluids are pushed into the cephalothorax; the pressure causes the skin under the carapace (the top portion of the cephalothorax) and the abdomen to split (Fig. 4.14, right). The spider makes rhythmical contractions of the body, pushing outward away from the surface where it is positioned. The old carapace falls away and the new cephalothorax emerges from the old exoskeleton. The legs start to slide their way out of the long tubes of skin (Fig. 4.15). The pulsing continues with rests in between. The new exoskeleton is extremely soft and pliable, otherwise the spider would never make it out safely. Eventually, the first pair of legs is freed from the old exoskeleton (Fig. 4.16, left). More pulsing and resting occurs as each pair of legs gains its freedom. If on a vertical surface, the spider leans backward so that all the legs can be extracted from the soon to be cast skin, using gravity to help in the extraction. Once the legs are free, the spider bends all of them so that the tips touch each other, and may remain motionless for a few minutes (Fig. 4.16, right). The abdomen separates from the exoskeleton and the spider may hang upside down, attached to the old exoskeleton by its spinnerets (the organs through which silk is emitted from the abdomen). The flimsy legs start to become stronger. At this point, the spider is extremely vulnerable to predators; molting typically occurs in the spider’s

Fig. 4.15. The spider is starting the process of extracting its legs from the exoskeleton (left). The legs are about half way out (right).

Fig. 4.16. The spider’s legs are strongly bent as the spider struggles to get them free (left). The spider has successfully removed its legs and cradles them under its body while hanging upside down (right).

retreat where it cannot be harmed. The just-molted recluse spider is very pale in both its legs and its cephalothorax, and the violin will lack pigment and is only defined by the rows of hairs (Fig. 4.17). Within an hour or so, the spider rights itself and its legs become more functional. The brown 55

Fig. 4.17. The newly emerged brown recluse is extremely pale and has no pigment in the violin area of the cephalothorax.

Fig. 4.18. The shed exoskeleton is left behind and is a useful indicator that a recluse population has been present at some point. Notice, near the top of the photo, the carapace with the violin pattern which has separated from the rest of the exoskeleton.

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recluse is then mobile but is still vulnerable for a few days as pigment and other proteins are deposited in the exoskeleton to strengthen it. Within 24 to 30 hours, the spider is ready to feed again, starting the development process of the next instar, or, if mature, start looking for a mate. The old exoskeleton is left behind in the asterisk pattern (Fig. 4.18). This is a diagnostic indicator of recluse spider presence at some point in the past and is useful for documenting a recluse infestation in a structure.

Lack of Leg Autotomy and Regeneration Many spiders display a defensive response known as autotomy, in which they shed a leg if it is grabbed by a predator. This not only prevents a predator from hauling in a spider by the leg but also, if the predator is another spider, it ensures that venom does not reach the rest of the bitten spider’s body. Legs undergoing autotomization have a fracture plate at a specific joint between the coxa and trochanter (the two leg segments closest to the spider’s body). If a spider is going to lose a leg, it is best to lose the entire appendage instead of losing only half of it, which would then be sticking out from the body, getting in the spider’s way. Basically, the spider loses the entire leg and then changes its gait to compensate for the loss. In one example, an immature huntsman spider had seven legs. The spider molted and regenerated the missing leg with one of half the normal size. It molted again a few weeks later, whereupon the regenerated leg was as long as the others. However, it takes significant trauma for leg loss to occur in recluse spiders. Once a leg is lost, a recluse spider does not regenerate a new one with subsequent molts. It is rare to find a recluse spider in nature with fewer than eight legs.

Development of Venom A study was performed on the venom development of the South American spider Loxosceles intermedia. The eggs and the second instar spiderlings did not have measurable quantities of the toxic recluse venom enzyme sphingomyelinase D. This compound started developing in the third instar and kept increasing until adulthood. In a South American species, the female has more potent venom than the male; it is not known if this is a universal trait for all Loxosceles species.

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The toxicity of the isolated sphingomyelinase D is almost as potent as that of the crude venom. It is this component that is responsible for causing skin lesions in humans, and it is highly toxic to insects. In fact, the main function for this venom component is to subdue insect prey, and its negative effects on humans are just a coincidence of venom chemistry.

Silk The brown recluse spider uses silk to line its retreat, which it wedges into a tight space such as under a rock in natural conditions or into a crack in a baseboard or stairs in a home. It may also extend some silk threads a short distance away from the entrance of the web. If prey gets stuck in the web, the struggling vibrations alert the spider to its presence and the spider rushes out to deliver a bite to prevent the prey from escaping. Within the araneomorph spiders, there are two large taxonomic divisions, the cribellates (having a cribellum) and the ecribellates (lacking a cribellum). A cribellum is a silk-producing plate at the posterior end of the ventral surface of the abdomen with a field of many spigots that spew out silk fibers, which become ribbons of silk that possess a curly structure somewhat like a skein of wool. The fibers are not sticky but they behave much like Velcro, causing the spine- and hook-bearing legs of arthropods to get tangled so that the prey is detained. This is in contrast to the archetypical orb-weaver which lays out a web of many thin fibers covered with globules of adhesive glue. Although Loxosceles spiders do not have a cribellum, their silk nevertheless behaves much like cribellate silk, detaining prey by entangling it. Experiments with brown recluse silk show that the structure of the fibers is composed of ribbon-like strands.

Prey Capture Brown recluses exhibit two types of prey hunting strategies. Some show site fidelity, hiding during the day in a retreat such as a slot in a sliding window or a hole at the base of a staircase and then emerging at night and waiting for a prey item to land nearby. The recluse then subdues the victim. These spiders are found in almost the same spot for consecutive nights. Their second strategy involves actively moving about the habitat, with the purpose of running into prey of a suitable size for paralyzing and consuming. In capturing prey, a brown recluse responds quickly to detected vibrations, then rushes toward the prey if the spider feels safe doing so. It

LIFE HISTORY AND BIOLOGY

exhibits different prey capture techniques depending on the prey item. If the prey is a harmless fly, cockroach, or termite, the recluse grabs it immediately with its fangs and holds on for a period of several seconds up to half a minute, injecting venom and often dragging its meal backward toward its retreat where it is safe to feed. However, if the prey is larger than the spider or might be dangerous, the spider strokes the prey with its first two pairs of legs to get an assessment of its size and general feistiness. In feeding experiments with large grasshoppers with hind legs removed, brown recluses did not bite until 6 minutes into the interaction. The spider quickly lunges, looking for a soft spot like a joint where it can sink its fangs into thin tissue. If successful, the spider then backs away and waits to see if the prey continues to struggle. Additional struggling will elicit more biting and injection of venom until the prey becomes immobile. The first bites are peripheral, with later bites on more central locations of the body. Sometimes if the prey is rather large, the recluse may ride the prey like a bucking bronco, biting it until paralysis sets in. If the recluse can grab an appendage like a leg or an antenna, it sits with the appendage held in its fangs, most likely injecting more venom into the body. The prey slowly becomes immobile, at which point the spider may approach and insert its fangs into the neck region or the side. Paralysis often happens within a few minutes, and the spider then starts feeding. Recluse spiders do not wrap their prey with silk. Many spiders start feeding on the main body. When a fly is their prey, brown recluses do prefer to feed on the head or the abdomen. However, with other prey, such as grasshoppers, they prefer to feed on peripheral structures: it is comical to see a brown recluse holding a leg or even an antenna for a long time, siphoning out the liquids. In the older literature, spiders in general are said to inject digestive juices into their prey so digestion can occur inside the prey’s body, turning it into “soup,” and then sucking out the nutrients from the dead prey. However, a study with spiders of the genus Uloborus showed that these spiders actually regurgitate the juices directly onto the surface of the prey’s exoskeleton and then suck up the fluids from the outside. Whether this happens with brown recluses or other Loxosceles species is unknown. In the experimental study with large grasshoppers, brown recluses fed for an average of about 10 hours with some feeding for 24 hours. With smaller prey, they feed for shorter times. In a 2003 study, brown recluses were reported to preferentially scavenge dead prey items, a behavior that was proposed to be a mechanism for

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survival. However, there are many reports in the scientific literature of scavenging by many different spiders across varied genera. One study offered dead crickets to 100 spiders from at least 29 species in 24 genera and 11 families to see if scavenging was a common behavior or if it was specific to brown recluses. Twenty brown recluses were also tested. Of the 100 nonrecluse spiders, 99 fed on dead prey, as did all 20 brown recluses. Therefore, scavenging behavior in spiders is a common opportunistic endeavor in general. This was also reinforced by the fact that some of the scavenging spiders were web spinners that would only encounter dead prey if it fell dead from the sky, an unlikely scenario or at least one that would be extremely rare. Therefore, there would not be much evolutionary pressure for scavenging behavior to develop in web-spinning spiders. Additionally, another study reexamined the conclusions of the first and found that scavenging behavior in brown recluse spiders can be modified depending on the size of the prey and degree of starvation of the spider, with brown recluses preferring live over dead prey. Thus, scavenging behavior is dependent upon factors such as these, and there is nothing special about the brown recluse behavior of scavenging dead prey.

Prey Recluse spiders are generalist predators. They will eat just about anything that they can subdue, including creatures larger than themselves: wasps, ants, beetles, isopods, cockroaches, and spiders including other recluses. In a home in Kansas, a brown recluse was seen eating a pompilid wasp and a kissing bug of the genus Triatoma, the latter of which is a potentially medically important insect. Pest control personnel in the Midwest notice that brown recluse populations seem to correlate with the presence of silverfish in attics, although this may just be circumstantial association with both species preferring the same habitat and environmental conditions. However, an arachnologist at the Museum of Comparative Zoology at Harvard University remarked that the Chilean recluse, L. laeta, became established in the building in the 1940s and seemed to thrive on silverfish living there. About the same time that the museum researchers started finding the recluse spiders, they stopped complaining that silverfish were eating the labels off their specimen jars. The prey of L. laeta in South America and the brown recluse spider are very similar whether the prey are collected from webs outdoors or inside buildings, and not surprisingly, with more diversity occurring for the outdoor webs. Another study documented prey

LIFE HISTORY AND BIOLOGY

being fed upon by recluse spiders collected in the field. In addition to the usual ants, flies, and other spiders, a recluse in Arizona was feeding on a scorpion, and a South American species was feeding on a juvenile recluse of the same species. In the laboratory, brown recluses willingly subdue crickets, fruit flies, house flies, cockroaches, mealworms, termites, and small caterpillars. These types of prey are highly desirable because the spiders are able to ingest large quantities of nutrients, plumping up greatly and maximizing the time between feedings, which is convenient for the researcher who is providing the food. However, it is best to offer prey such as flies, which do not possess chewing mouthparts, or termites, which do not eat insects, because if the recluse is molting and vulnerable, the spider can become the meal. Recluse spiders have never been recorded as preying on vertebrates, whereas there are records of black widows feeding on mice, lizards, and snakes, and orb weavers catch small birds in their webs, especially hummingbirds.

Habitat In a natural setting, brown recluse spiders can be found under rocks, particularly where the rocks are under an overhang protecting them from the weather. They are also found in rotting logs and under loose tree bark. Where humans have influence, recluse spiders also make their homes in cardboard boxes, woodpiles, and tarps, and under discarded tires, stacked piles of shingles, and broken concrete or asphalt. In structures built for humans, brown recluses are typically found in areas where the light level is low, such as basements and attics, in cupboards, near the floor under door sills and cracks in baseboards, behind picture frames, bookshelves and dressers, inside couches, and pretty much anywhere where humans provide a bounteous supply of cracks and crevices for them to take up residence. In barns, silos, and outbuildings, recluse populations can get quite large. Pulling back tar paper, plywood sheets, or other large and flat material may uncover dozens of brown recluse spiders. They also can be found under feed sacks, hay bales, and just about any piece of clutter under which they can squeeze themselves and hide. South Americans refer to their Loxosceles spiders as araña de los rincones (spider in the corner) and araña de detrás de los cuadros (spider behind the picture).

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In the southwestern deserts, several Loxosceles species exist such as the desert recluse, L. deserta, and the Arizona recluse, L. arizonica. Because the habitat is obviously different from that of the Midwest, they are found in slightly different places such as in or under dead cactuses, in rodent burrows, and in the sticks of pack rat middens. Although the southwestern species look somewhat similar to brown recluses, there are some behavioral differences. In the Midwest, the brown recluse is referred to as synanthropic, living “with humans,” and with its population actually increasing in association with humans, like those of pigeons, cockroaches, and rats. The brown recluse considers the structures in which humans live and work to be excellent for survival, so it moves in and proliferates. In contrast, many of the southwestern desert species only inhabit homes amid native desert landscaping. In places like metropolitan Phoenix and Palm Springs, where heavily watered green vegetation is used in landscaping, the southwestern desert recluse species are rare or nonexistent.

Population Size In habitats providing adequate support for survival, recluse spiders populations can rise to high levels. In a study of a home in Lenexa, Kansas, a family of four collected 2,055 brown recluse spiders in 6 months. This was a rural home; the original portion was built in the 1850s and was reported to be the residence of Wild Bill Hickok when he lived in Johnson County. The house, barn, and other outbuildings were chock-full of recluse spiders. In another Kansas study using sticky traps, brown recluses were collected in 22 of 25 homes with an average of 83.5 brown recluses per house (range = 1 to 526). In a study of urban and rural homes in Chile, Chilean recluse spiders were found in 29% of the homes. The five most infested homes averaged 163 recluse spiders (range = 106 to 222). A pest control worker in Memphis placed sticky traps in a home where occupants had complaints of brown recluse spiders, and in 24 hours a trap underneath a couch caught 44 specimens. Arachnologists in Oklahoma collected over 1,100 brown recluses in three consecutive nights in one barn. Despite the large number of recluse spiders found in the these structures, only one person was ever bitten (in the Lenexa home) after 11 years of occupancy, and in the five high-populated homes in South America, incidents of recluse spider bites were noted as nonexistent. Loxosceles spiders can attain a high population density because they are very tolerant of each other. They are not truly social like some orb weavers

LIFE HISTORY AND BIOLOGY

of the Metepeira species from Mexico or the Stegodyphus species from Africa, which cooperate to capture and share prey as well as to defend colonies. However, recluses will tolerate each other’s presence even in large numbers. At a house in Yucca Valley in the southern California desert, tipping over a 2-by-3-foot doghouse revealed 12 live desert recluses, many of which were adults. Recluses are one of the easiest spiders to rear in the laboratory because they tolerate others of the same species so readily.

Dispersal One curious life history aspect of brown recluses is their inability to disperse easily. Many spiders of other species engage in a behavior called ballooning: while still small, a spiderling may climb to the top of a fence post or piece of vegetation on a warm day when there are updrafts, and emit a strand of silk that floats upward. When the upward lift forces on the silk become stronger than gravity, the spiderling and its silk are lifted skyward. In Charlotte’s Web, at the end, this is what happens to most of Charlotte’s babies, who float away much to Wilbur the Pig’s dismay. Ballooning spiders have been found at 15,000 feet (collected by airplanes fitted with special collecting gear) and also hundreds of miles offshore, landing on ships. This is one behavior by which many spiders are able to become first colonizers in areas disturbed either by natural disruptions or by human-related changes in an environment. However, haplogyne spiders such as recluses do not balloon, so recluses have very limited ability to disperse over great distances. An arachnologist in Lawrence, Kansas (a city well within the brown recluse’s indigenous range), for example, set out cardboard rolls in his backyard which attracted spiders into the corrugations. The cardboard was sampled every month for a year, and 759 spiders were collected. None of these were brown recluses. If brown recluses were normally running through this backyard, it seems that some of them would have been found inside the cardboard rolls. In another example, a collector in Georgia found and noted an oak tree that had brown recluses. Using the collector’s notebook, researchers were able to locate the tree 7 years later, and found that it had fallen with age but that brown recluses still lived under the loose bark. When the researchers looked around the fallen tree for half a mile in habitat normally supportive of recluse spiders, they found none, even in a pile of wood from a collapsed building only 10 feet away nor in an abandoned, dilapidated house with two rotting oak trees 1,000 feet away. So even given 7 years to disperse, the

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spiders were still found only associated with the one specific previously infested oak tree. The same thing is true of recluses in human structures: one may find dozens to hundreds of them within a particular barn or shed but within 50 feet from the infested building, there may be a house or other structure where the spiders are uncommon or do not occur. At a home in Columbia, Missouri, inspection of a garage found a dozen recluses on the walls, but they were not seen inside the house, which was about 25 feet from the garage. In Los Angeles County in California, when an building infested by the Chilean recluse, L. laeta, was razed and replaced, the new building did not get reinfested. Arachnologists who live in indigenous recluse areas admit to never having seen recluses moving between buildings, even at night. Considering that arachnologists will bend down to investigate anything crawling on the ground, this is pretty strong evidence that recluse travel between buildings is quite rare, at least by large-sized recluses. Recluse spiders also are only rarely found on the exterior of structures. They will be plentiful inside a barn interior and they may move respectable distances within it but rarely are they seen on its walls or roof. Some species of recluses are found in caves, so the genus may have an underlying affinity for staying inside a habitat as opposed to being exposed outside. Global warming is an issue affecting many components of our natural world and with it, scientists are seeing shifts of animals to habitats farther north in the Northern Hemisphere and at higher elevations than previously found. One study included an estimate of the brown recluse’s movement northward in the United States and Canada, based on investigation of how the environment farther north will become increasingly similar to that of areas where brown recluses currently live. However, this does not mean that brown recluse spiders will be packing their bags and moving north. These predictions may be accurate for winged creatures, but in spite of some doomsday reports in the media, the brown recluse’s inability to easily disperse may prevent it from responding to changing environmental conditions. Rather than expanding northward, the spider’s range may shrink as warmer conditions in its southern portion make the South inhospitable while the northern boundaries of its range remain much the same.

Seasonal Pattern of Activity Brown recluse spiders exhibit a predictable seasonality, being commonly found during the summer and disappearing in the winter. There are probably differences as one moves north to south through the spider’s range

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Number of recluse submissions

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Month

Fig. 4.19. Submissions of recluse spiders from the general public from a nationwide study. This graph demonstrates that recluse spiders are found more often during the summer when the spiders are more active. Data were reconfigured from Vetter 2011.

but overall, in specimens submitted in a nationwide study, people found brown recluses most often from May through August (Fig. 4.19). In the densely infested home in Lenexa, Kansas, brown recluses become active around May and then disappear around the end of September, even though this is a heated structure where they could be active all year round. Possibly, the peripheral portions of the house are cooler during the winter, thereby limiting activity. Yet the brown recluses could also merely be responding to the natural light cycle. In the natural habitats where they have evolved, when day length gets short toward winter it is better to hole up to avoid the cold. The amount of seasonal sunlight is a better indicator of hospitable weather than is temperature alone. In addition, prey activity also decreases in the winter so that if the spiders remained active, they might starve. The Arizona recluse has an opposite activity cycle in the mountains around Tucson. In a study in that region, they were more readily found, under dead cactuses and in similar spots, during the winter months. In the summer, specimens were hard to find, most probably because the daytime heat would have been fatal to them. The spiders were most likely far underground in rodent burrows and other retreats in order to escape the heat; more than likely they were active on the desert surface during the night.

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In the desert east of Palm Springs (near Chiriaco Summit—1300-foot elevation), desert recluses were caught in pitfall traps from April to about October. In the Mojave Desert, at a University of California research facility (Sweeney Granite Mountains—4400-foot elevation), they were collected in pitfall traps from May through September.

Heat and Cold Tolerance The range of temperature limits for brown recluse activity has been calculated to be 4.5 °C to 43 °C (40 °F to 109 °F). At the lower limit, exposure to –10 °C and –7 °C (14 °F and 19 °F) for 4 hours killed 47% of brown recluses and –5 °C (23 °F) was 100% lethal, but all survived when kept at 0 °C (32 °F) for 30 days. In a study in Illinois, a leaf litter temperature of –5 °C (23 °F) was determined to be the probable major environmental factor causing brown recluse spiders to be rare in the northern third of the state. For the South American recluse, L. intermedia, the upper limit for heat tolerance with a one-hour exposure was determined to be between 32 °C and 35 °C (89 °F and 95 °F), which killed half of the experimental spiders.

Collecting Recluse Spiders The easiest way to collect live brown recluses for research or general enjoyment is to seek them out at night in structures when they emerge from hiding places and are active. They do not immediately respond negatively to light so lights can be turned on in an attic or basement and the recluses will not scurry away as do some spiders. However, recluses are very sensitive to vibrations from the placement of human feet in walking and from the moving of objects like plywood. When they sense human-caused vibration, they vanish instantly. The best way to catch a spider is to slowly lower the open end of a vial over it and have the spider run up into the vial. Before beginning the hunt, cut a piece of paper toweling about the same length as the vial and wide enough for it to cover half the vial’s inner circumference. The curvature of the vial should hold the paper inside, but to check, invert the container after putting in the paper to ensure that it stays in the vial when turned upside down. Approach the spider with the paper hanging a little out of the vial opening and place it over the spider gently (so the legs don’t get ripped off ). The spider should run up the paper into the vial. Then the vial

LIFE HISTORY AND BIOLOGY

can be safely capped. Alternatively, a piece of stiff paper (like an index card) can be slid under the inverted vial, then everything flipped right side up and capped, again taking care not to rip off legs. The spider will eventually attach silk to the paper towel, which will allow it to capture prey more easily and may be critical for increasing the chances of successful molting if it is immature. The paper towel also prevents the spider from flailing continuously against the walls of the vial, which would cause the spider to exhaust itself and die.

Rearing of Recluses in Captivity For those scientists and avid natural history buffs wishing to rear recluse spiders for research or general interest, it is actually quite an easy endeavor because recluse spiders are not habitually cannibalistic. The initial requirement is to place a recluse egg sac into a clear, plastic 1-gallon jar and feed the spiderlings once they emerge. Do not use a glass jar in case it falls, breaks, and then releases dozens of little recluses somewhere that it would be best not to have them running freely. Air holes are typically unnecessary, but if ventilation is required, use a hole saw to cut a round hole in the lid—preferably a plastic one. Fine-mesh brass screening from a hardware store can be cut to overlap the edge of the hole by about 1/4 to 1/2 an inch. Hot glue can be used to affix the screen completely to the underside of the lid, leaving no openings for escape along the edge of the hole. The inside portion of the screen should be completely glued down so that no flaps are sticking up; otherwise, spiderlings may use the space between the lid and mesh at the top to set up a web, which could lead to an escape if the lid is carelessly placed on a countertop. For extra security, turn the lid right side up and use hot glue on the top where the screen emerges from the edge of the hole. Once the jar is readied, paper towels, preferably single-ply, should be ripped into about four equal-sized pieces (which will make the transfer of spiders to individual containers easier later on), crumpled up into loosely wadded balls and tossed into the bottom of the plastic jar. The baby recluses will use the nooks and crannies to hide and build webs. The jar should be fi lled about one-third full of these crumpled pieces. Although large recluses have trouble climbing up plastic, spiderlings can do so more easily. They could then lay down silk on the plastic walls which might allow them to climb to the lid when larger. Typically the spiderlings will stay low down in the jar, but whenever opening the jar, it

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would be best to place it in a white or tan plastic dish pan so you can see the spiderlings if they try to escape. Remove the lid, inspect the inner surface for spiderlings, and place it facing downward in the dish pan next to the jar. This way even if a spiderling is on the inside of the lid, it will be contained. As the lid is placed back on to the jar, the dish pan should be examined for spiderlings which may have crawled off the lid or out of the jar. In addition, hands and forearms should also be inspected for tiny spiderlings, which may not be felt crawling across the skin. Another precaution is to avoid wearing a long-sleeved shirt; otherwise, the spiderlings might crawl onto the fabric. With bare arms, it will be easier to detect the presence of a spiderling, which will be too small to inflict a bite when crawling across your arm hairs. To feeding the spiderlings, fruit flies, termites, baby cockroaches, or anything about the same size as the spiderlings can be thrown into the rearing jar. A compost bin is a great source of spider food and can naturally raise fruit flies outside the house. To aid in collecting fruit flies, an empty glass jar should be kept in the refrigerator. At feeding time, the glass jar should be taken out, an insect net should be swished over the compost bin to collect fruit fl ies and the jar should then be placed into the net to scoop up the flies. The cold glass will immobilize the flies in a few seconds, whereupon they can be poured into the recluse rearing jar. As long as the flies aren’t exposed to the cold glass for long, they will quickly resuscitate inside the recluse jar and the babies will start feasting on them. There is no need to give the recluse spiders water as they get all their fluids from their prey. In fact, providing water may be very detrimental to the spiders as it may induce mold. Recluses prefer dry habitat so water is unnecessary. They are not imbibing water in attics or garages and they are doing just fine. Recluses develop slowly, so it will take months for them to grow from small spiderlings to adult spiders. However, it is best to give the spiders a rest between meals. Do not feed them every day, expecting to push them through to adulthood faster. In research with other spider species, it has been found that maximally feeding spiderlings resulted in a higher fatality rate than if the feeding regimen was moderate. Because recluses can go long periods without food, feeding them once a week should be sufficient for them to grow. It is not uncommon for some babies in a recluse egg sac to grow up to about half of the adult size (about the fourth or fifth instar) while others don’t grow much at all. As the spiderlings get larger, they should be

LIFE HISTORY AND BIOLOGY

removed into individual containers so they can be fed larger prey. It is more time-consuming to feed spiders individually, but once they reach about the halfway point to maturity, they can be fed once or twice a month and keep growing. Feeding this often should be enough to prevent them from dying from starvation. If the spider is very pale, do not offer food. It has just recently molted and is very soft. If you happen to throw in a live insect possessing mouthparts, such as a roach or a cricket, the prey may end up eating the spider. To transfer small recluses from the rearing jar to individual vials, it is best to have a second, light-colored dish pan handy. The rearing jar and the removed lid should be placed in the first dish pan and a piece of crumpled paper towel should be moved one shred at a time to the second dish pan. (This is where having one-ply towels makes it easier because otherwise, recluses will crawl in between the sheets, making harvesting spiderlings a more exciting adventure.) After the paper towel is removed, replace the lid on the jar to prevent unnoticed spiderling escape. Have lots of vials with paper inserts in place at the ready with lids nearby, and as you unravel the crumpled paper towel, scoop the spiderlings into their new homes. Make sure no spiderlings are left in the dish pan or on the paper towels. As an extra precaution, after examining a piece of paper towel for spiderlings and finding no more of them, crumple the shred tightly to kill any spiderling that might have escaped notice and place it in the freezer in a zipper lock plastic bag for 24 hours, just to make sure that any remaining recluse babies that were missed are killed and not unintentionally liberated.

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To begin with, it is essential to explain how the information regarding the distribution of any spider accumulates. It is always important to understand how a body of knowledge in any biological area is built up, but even more so when dealing with brown recluse spiders because of the tremendous amount of misinformation in circulation, in both the past and the present. Misinformation about brown recluses has two main sources: first, misidentification of harmless spiders that has been going on for decades, so that incorrect information is now perceived as fact (dealt with in this chapter, so far as misidentifications in nonindigenous localities is concerned); and secondly, physicians’ diagnoses or acquaintances’ suggestions that a skin lesion is a brown recluse bite, so that brown recluses must occur in the area concerned (see Chapter 7). Those who doubt the information presented in this chapter should collect spiders they think are recluses and show them to a qualified arachnologist. This may require some work but one shouldn’t rely on medical personnel, pest control personnel, or even entomologists, because it is likely that these people have no training in spider identification. Although some of them may be able to identify a recluse spider correctly, they may not be able to accurately identify a nonrecluse spider by name. In the past, this has often led to the identification of common harmless spiders as recluses. Many nonarachnologists in nonindigenous areas will probably be very surprised to find out the actual identity of the spiders that they have been misidentifying as brown recluses for years. As an example of the extent of the belief of the ubiquity of the brown recluse spider in North America, a study published in 2005 in the Journal of Medical Entomology, mentioned in Chapter 3, documented all the arachnids 71

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submitted by people who thought they might have collected a brown recluse spider. These specimens were submitted from forty-nine of the fift y US states, although the brown recluse is basically limited to a very welldemarcated area encompassing approximately seventeen states. Nonetheless, it is perceived to occur throughout North America including Canada. Here is how information on the distribution of a spider—or any biological entity—is obtained; this involves explaining some of the history of the nuts and bolts of taxonomy. Arachnologists, entomologists, natural history buffs, and citizen scientists have been collecting spiders in North America since the nineteenth century. Spider collections can result from several methods. Collectors may go to a particular region and collect all the arachnids they encounter whether they can identify them or not. Sometimes an arachnologist may focus on finding one particular species or genus of spider, but as part of the collection process may collect many other species as well. Or an arachnologist may be collecting in a geographic area where no knowledge exists about the spider fauna and may make new discoveries. Additionally, an entomologist seeking beetles or crickets may find spiders in the collection devices, separate them from the desired critters, and give the spiders to a museum, knowing nothing about their identity. Other distribution information may come from an ecological study conducted by a researcher who has no interest in spiders in particular but is investigating the effects of forest fires or heavy metal ecological contamination on the arthropod composition of an area. Specimens from all these sources were sent to museums for safekeeping, fi rst in Europe in the nineteenth century (because the first collectors were based there) and then later in the century in North America as well. Museums provide central locations for the accumulation of scientific material, which allow arachnologists to examine specimens years, decades, or even centuries after they have been collected. The term for placing specimens is depositing, and the process of cataloguing and storing spiders is curating. Often specimens are distributed to several museums because if “all the eggs are put in one basket,” some disaster, either natural or human-made, can destroy the specimens or cause their loss. All of the scientific material deposited at the California Academy of Sciences in San Francisco prior to 1906, for example, was destroyed in a fire after the historic earthquake, and many scientific specimens were destroyed in museums across Europe as a result of the devastation caused by World War II. Additionally, a museum employee may put a vial back in the wrong place; the specimen may never be located again and would then be lost to science.

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In any case, museums are depositories of various organisms from the worldwide collection efforts of hundreds of scientists over several centuries. Some museums boast thousands or even hundreds of thousands of spiders that have been collected, sorted, identified to some degree (typically by genus and maybe also by species), and then carefully stored together with similar specimens. Decades later, when an arachnologist wants to work on a particular family, genus, or species, he or she will request a loan of the collected material and it will be shipped to the requester for examination (for a study that sometimes takes years to complete). If sensitive or large specimens cannot be shipped, the scientist has to visit the museum in person to examine the specimens on the premises. In many respects, the collection and curating of organisms is like the process of accumulating books in a vast collection like the Library of Congress. The largest US spider collection is at the American Museum of Natural History in New York, with estimated holdings of one million spiders, including hundreds of specimens of recluse spiders of many species. Each spider (or sample of spiders collected from the same place during the same period of time) is placed inside a vial with a small label detailing its identity, where it was collected (country, state, county, city, or closest location, and in recent years, GPS locality), the date of collection, and the collector’s name. This provides a historical record that enables future researchers to use the information: by going through hundreds or thousands of vial labels one can determine where a spider species occurs. In the case of a common spider like the brown recluse, this procedure gives an accurate record of where the spider is found. In the case of a rare or uncommonly collected spider, the procedure shows where arachnologists have been actively searching and may not accurately reflect the actual distribution of the organism, so that additional collecting will better defi ne its distribution. Remember, science is like a flowing stream: we know a good deal but many discoveries are still to be made. New spider species are still being found in North America but, mostly in the remote, sparsely inhabited western portion of the continent, in caves or on mountaintops. In addition, distribution data can come from publications giving the results of extensive collection in a limited area such as one state. Though such regional publications are sometimes not easy to retrieve. In the case of common organisms, only a few specimens are retained for museum curation as museums have limited storage space and would not want a

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million specimens of the common house fly or the honey bee such as were collected throughout, say, Alabama or Wisconsin. In such cases, scientists may send ten to fift y specimens (called vouchers) from a wide area as representatives of the species they are researching even though their publication may be based on thousands of specimens.

The Native Range of the Brown Recluse Spider One amazingly paradoxical aspect about the brown recluse is that despite its infamous reputation and occasional medical significance, information regarding its distribution is sometimes lacking for specific areas of the United States. Some states, like Nebraska and Illinois, have a very well-documented spider fauna; for other states, such as Louisiana, Tennessee, and Kentucky, no publication exists that adequately describes the distribution of the brown recluse. Most of the knowledge of spiders in these latter states is based on oral information from people who deal with the creatures. Some of these people are state officials, such as public health department staff who aren’t arachnologists, but fi nd that spiders become part of their job. Of course, generating knowledge of the distribution of the brown recluse spider costs money for salaries, travel, collecting, and organization of the data. Understandably, the brown recluse does not attract the same outpouring of government research funding as does something like Lyme disease or West Nile virus which are more dangerous threats to human health. As a result, the information presented here is based on a diverse conglomeration of sources: detailed scientific studies, examination of specimens from museums, distribution information from local publications, discussions with dozens of arachnologists who have collected thousands of spiders over decades in specific areas, correspondence with public and environmental health officials who deal with spiders, thousands of specimens submitted by the general public over decades, and interactions with hundreds of pest control operators at continuing education seminars. The brown recluse spider lives in the south and central United States from southeastern Nebraska to southwestern Ohio and south through most of Texas and into northwestern Georgia (Fig. 5.1). This is where populations of the spider can be reliably found, or at the least, this is where it would not be surprising to find it. In the central portions of the range, for example Missouri and Arkansas, it is common and abundant, so that one would expect to find it in any house and in many houses along a street,

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Deserta Arizonica

Apachea Blanda

Reclusa

Devia

Fig. 5.1. Loxosceles species with widespread distribution in the United States, showing where they are most likely to be found.

with many brown recluse spiders per house. Toward the margins of known brown recluse spider territory, the populations become harder to find. A rain cloud is a useful analogy. Suppose a person is standing under the center of the cloud where the heaviest rainfall should occur. Raindrops should be common and easy to find, and two raindrops landing on outstretched hands should be close to one another and the time between them landing short. However, as this person moves out to the edge of the cloud toward the sunshine, the raindrops still fall but there are fewer of them, they are more widely spaced, and the time between finding two of them is greater than under the center of the cloud. The same thing occurs with an animal population. They are dense and easy to find in the middle of their range but as the margins of their acceptable habitat are reached, the animals become less common, they are harder to find, they may exist in isolated pockets instead of being broadly distributed, and when one is found, it takes a lot more effort to find the next one, which may be much farther away. The state-by-state distribution of Loxosceles reclusa (going clockwise from Nebraska), so far as it is known from the above sources, is as follows. Missouri and Arkansas are not included, as brown recluses are common throughout both states.

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Nebraska. The arachnological record is quite good for Nebraska, with county-by-county records available. The brown recluse is only known to inhabit the southeastern corner of the state and is found only inside structures, being absent from the natural or human-landscaped environment. Iowa. Information is solid but sparse, coming mainly from a distribution study in the Journal of Medical Entomology in 2014. Brown recluses are very rare in the state, have never been documented in the northern counties, and are occasionally found in the southern counties. Some entomologists who work with spiders in Iowa have never personally collected a brown recluse and a valid identification occurs infrequently. Illinois. The article mentioned for Iowa above also provides documentation for Illinois. The brown recluse spider is very common and abundant both inside and outside structures in the southern third of the state, is found almost exclusively inside buildings in the middle third, and is extremely rare or nonexistent in the northern third, including Chicago. Although some brown recluses have been found in Chicago suburbs, these finds are considered to be transported spiders and not part of natural existing populations. Indiana. There is almost nothing published for Indiana but according to arachnologists there, the distribution is similar to that in Illinois: common in the southern third, absent in the northern third, and diminishing in the middle third. Ohio. The spider fauna of Ohio is extremely well sampled. Rich Bradley, now a retired professor from Ohio State University at Marion, ran the Ohio Spider Survey for 20 years, collecting all over the state. During that time period, the survey had amassed over 40,000 spiders encompassing 642 species. Ohio also has the distinction of having a tremendous number of active arachnologists, in the latter half of the twentieth century and into the early twenty-first century it has been a mecca of American arachnology, with many professors and their students scouring the state. As a result, the information regarding brown recluses is very solid. The brown recluse spider is not very common in Ohio. It is known from the southwestern portion near Cincinnati and Dayton, but is still very rare there and is not often found elsewhere. For more on the spiders of Ohio, see Bradley’s 2004 book under this chapter in the reference list. Kentucky. The information from this state originates only from museum specimens and discussions with pest control personnel; there is nothing

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published on the spider fauna of Kentucky. The brown recluse is extremely common in western and central portions of the state. The general consensus of arachnologists throughout the region is that as one approaches the western slope of the Appalachian mountains in the eastern portion of the state, brown recluses get more difficult to find. Tennessee. As with Kentucky, not much information is available, populations are dense in the western and central but not in the eastern portions of the state, although it is not impossible to find them in spot locations in eastern Tennessee. Knoxville appears to be the location where brown recluses transition from common to rare. Virginia and North Carolina. These two states are grouped together because just their western tips may possibly extend into brown recluse territory. There is little information from these states but the consensus is that the brown recluse is extremely rare with only occasional finds. A retired professor from Western Carolina University in Cullowhee (western North Carolina) collected hundreds of thousands of spiders in the Smoky Mountain region over decades. He stated that he had never collected recluses in his area and that finds were very rare. About ten buildings in each state are, or at some point were, heavily infested with brown recluses. However, each of these buildings is an isolated case; the spiders are not spreading. A North Carolina arachnologist’s data collection showed twenty finds of Loxosceles spiders in thirty-three years, or one find every 18 months or so, many being interceptions of individual itinerant travelers rather than representatives of breeding populations. This is characteristic of the finds in a nonendemic state rather than one with an indigenous population. However, there has been one verified brown recluse bite in North Carolina with a second highly probable bite (of a person with a typical lesion and brown recluses found in the house.) South Carolina. Most likely, South Carolina is outside the native range of the brown recluse. An arachnologist at Clemson University knows of no locality in the state where one could go to collect a brown recluse, so this spider is surely not well established there. Where specimens have in fact been found, they were probably brought into the localities concerned. An older publication on the spider fauna of South Carolina contains the incorrect statement that “the brown recluse probably occurs statewide in human habitations,” based upon the misconception “the spider is now known from coast to coast.” Unproven and speculative statements like these spread incorrect information in the scientific, medical, and general literature.

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However, a later publication softened this stance to bring it more into line with what is currently known about the South Carolina situation: brown recluses are extremely rare. Georgia. A study published in 2009 in the Journal of Medical Entomology shows that brown recluse spiders are rare and are restricted to the northwestern and north central portion of the state. Almost all finds of brown recluses have been at least at a remove of one or two counties north of the Fall Line, which separates the Piedmont geological province in north Georgia from the Coastal Plain province in the south. The spiders are very rare in Atlanta. Alabama, Mississippi, Louisiana. Almost nothing is published for these three Gulf Coast states. For Alabama and Louisiana, there is virtually little data except oral information. One study stated that brown recluses were collected in every county in Mississippi, but provided no way of telling how common the spiders are. In a map accompanying the study, a southern Mississippi county where possibly only one specimen was found was shaded like a northern county where they are abundant. Examination of the field notes used in the study and specimens deposited in museums show many gaps in the information presented. In general, consensus from arachnologists in the southeastern states is that the closer one gets to the Gulf Coast, the less likely one is to find populations of the brown recluse. This is corroborated by the distribution pattern of the spider in Georgia and Texas and the lack of brown recluses in Florida. Texas. Although the data for Texas are not exceptional, Texas is another hotbed of American arachnology and the state is fairly well sampled. The brown recluse extends into most but not all of the state, but in the southern and southwestern portions of Texas, it gives way to other Loxosceles species: the Big Bend recluse, L. blanda, the Texas recluse, L. devia, and the Apache recluse, L. apachea. In effect, it would not be surprising to find a recluse spider of one of these four species anywhere in Texas with the aforementioned proviso that they should be less common along the Gulf Coast. This is corroborated by the fact that they are extremely common around Dallas, whereas according to entomological sources in Houston, the spiders are rare in that area. When a Houston entomologist wants brown recluses, he has to drive 100 miles inland to collect them. New Mexico. This state presents a problem because the human population is concentrated in a few cities and much of the state is wide-open

DISTRIBUTION

desert that has not been explored. Even so, there has been quite extensive sampling in some areas of New Mexico, first by Dave Richman (New Mexico State University—now retired) and also by Sandra Brantley (University of New Mexico), and there have been finds of the brown recluse along the eastern border of the state. In general, however, there is little knowledge of how extensive the population is in New Mexico. Oklahoma. There is nothing definitively published on brown recluse distribution in Oklahoma, but the available information documents the spider as extremely common and abundant throughout most of the state. Little is known regarding the western portion of the state. Kansas. As with Oklahoma, the spiders are common and abundant in the eastern portion of the state where the human population is concentrated. There is little information for the western portion of the state. The spider fauna for Colorado, to the west, is well documented and the brown recluse is not known to live in eastern Colorado, so somewhere in western Kansas as the plains rise up into the Rocky Mountains, the brown recluse disappears. However, there is no solid data to prove or dispute this, and the spiders are known from Hays and Garden City.

The Brown Recluse beyond Its Native Range Outside of its native range, the brown recluse spider is rarely found. Although it does sometimes get transported out of this region, most of the spiders probably die in their new environments, otherwise they would be regularly collected. There is no information as to whether death is caused by predators, detrimental environmental conditions such as desiccation, competition from spiders already living in the regions concerned, or other factors. On extremely rare occasions, a population of brown recluse spiders will establish itself in a new area but the author is aware of less than forty buildings in nonindigenous recluse areas known to have brown recluse populations. In comparison, to find forty buildings populated by brown recluse spiders in Kansas or Missouri, one would have to walk down just one residential street. Although these displaced populations can grow to very high density, typically the infestation is limited to one building. The brown recluse does not spread like many other nonnative organisms such as Africanized honey bees or starlings or the invasive kudzu plant.

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Frequently, in both the medical and popular literature, authors claim that the brown recluse is ubiquitous in North America because human commerce can transport it, hence it can be found anywhere in the country. Although this sounds reasonable, none of these authors who makes this claim ever investigates, let alone proves the next logical step: if brown recluses can be found anywhere, then they should be found in many places. On the contrary, several arachnological studies show an amazing absence of brown recluses in various American states and regions or in Canada. In reality, the known finds of brown recluses outside native regions are few and noteworthy when they happen. This is a key fact tending to disprove the numerous word-of-mouth stories one hears about people who have supposedly been bitten by these spiders, as well as the many medical diagnoses of brown recluse bites routinely made in nonnative areas. If a local seminar for a general audience, a college class, a pest control conference, or a zoo educational discussion meeting in an area outside the native range of any of the Loxosceles spiders is asked, “How many of you know someone who claims to have been bitten by a brown recluse?” typically between 25% and 50% of those present will raise their hands. Yet only one or two recluse spiders of any species may have been found in these areas throughout their collection history. If this many people were truly being bitten, then the spiders would be found in much greater numbers. A sample follows of what is known of bite diagnoses and spider fauna in various regions of North America outside of the range of any Loxosceles spider. Canada and Alaska. No brown recluses have ever been found north of the southern Canadian border. One brown recluse spider is listed from the Royal Ontario Museum, dated to 1980, which is actually a specimen of Loxosceles laeta—a species that is occasionally discovered around the world and sometimes turns up in museums. A single immature Loxosceles specimen was found in both the Royal Ontario Museum in 1950 and in Vancouver in 1961, and a single specimen of L. blanda was intercepted in Calgary in 2007. However, in contrast to the beliefs of many members of the general public and the medical community, Canadian arachnologists confidently state that there are no recluse spider populations in the country. No recluse spiders have ever been found in Alaska. All the same, there are several reports in Canadian medical journals of brown recluse spider bites causing skin lesions. Of course, no spiders of any kind were caught actually inflicting a bite and no Loxosceles spiders were collected in or known from the areas concerned. Yet even when an article

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was written in attempt to educate the medical community about these inconsistencies, an author of one of the original articles reporting a skin lesion as brown recluse bite still defended his diagnosis; he was willing to concede that the cause of the lesion may have not been a brown recluse, but he still was of the opinion that the cause had to be a spider bite even though no spider was seen in the incident. This exemplifies the bias toward spiders in explaining skin lesion injuries. No Canadian spider has positively been shown to cause such lesions yet these misconceptions continue. Connecticut. American arachnological luminary B. J. Kaston wrote a thousand-page book on the spiders of Connecticut that was for decades a bible of taxonomic arachnology, used by hundreds of arachnologists to learn how to identify spiders. Connecticut is a small state (60 by 90 miles); obviously, Kaston’s work is an extremely comprehensive tome. It does not list any recluse spider species as being routinely collected in the state, and although it was written several decades ago, there has been no colonization of the state by the brown recluse since then. This information is also pertinent to the rest of New England as well as New York State. Florida. Because of its tropical climate, Florida is pummeled by nonnative species, whether accidentally or purposefully established like the kudzu and Melaleuca plants and the brown widow spider, or dumped as unwanted pets like Mexican red-rump tarantulas, Burmese pythons, and piranhas. Despite the wonderful tropical weather in Florida, recluse spiders are not part of the native fauna nor have they ever established themselves except in rare, isolated cases. Many Floridians sent in specimens for a nationwide brown recluse study and for a project in Okaloosa County in the Florida panhandle, in which people were challenged to submit spiders thought to be recluses. Despite vehement tongue-lashings from the general public about the irresponsibility of stating that there are no brown recluses in the state, not one of the several hundred spiders submitted by Florida residents was a recluse. One house in Wintergarden had a population of the Chilean recluse where forty of the spiders were collected, but once discovered, the house was treated and the infestation was eliminated. Several Loxosceles specimens have been turned in since those studies, most of which were actually the Mediterranean not the brown recluse, but these were all interceptions of individual specimens and not representatives of established populations. An article in the Journal of Medical Entomology in 2004 documented only seventy Loxosceles spiders in Florida in 100 years of arachnological records (less than one per year) in comparison to a six-year compilation of data from

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the three Florida poison control centers that recorded 844 brown recluse spider bite reports (141 per year). An important point to take from the poison control data is that this data set is formed by people calling and reporting an incident. Most of the calls come from the general public, not the medical community. Therefore, poison control center data record only the perception of spider bite. A report of a spider bite is a report but not necessarily a bite. Washington State. This state has a strong arachnological history, and the curator of arachnids of the Burke Museum at the University of Washington currently provides extensive arachnological knowledge for the state extending back for decades. Only a handful of Loxosceles spiders are known to have been collected: three as interceptions and a small population of Mediterranean recluses in one building in Spokane. Yet the belief in the spider’s presence is persistent among residents and some members of the medical community. A study published in Toxicon in 2003 documented twenty-two physician diagnoses of recluse bites in a 41-month period. Also, many years ago, a Washington physician denigrated a victim of a yellow sac spider bite for not coming in sooner because he had “already diagnosed three brown recluse bites that day.”

Other Native Recluse Spiders Other than the brown recluse, ten additional indigenous North American Loxosceles species are found in the United States. Five of these native species have widespread distribution (Fig. 5.1) whereas the others have only been discovered in isolated canyons and desert areas. The apparent limited distribution may reflect the fact that the spiders live only in these isolated spots, or because arachnologists haven’t found all the places in these remote locations where they currently live. The two nonnative Loxosceles spiders in North America, L. rufescens and L. laeta, are discussed later in this chapter. Desert recluse, Loxosceles deserta. After the brown recluse, the desert recluse has the widest distribution in North America, from central Arizona west into California and south into Mexico. The desert recluse is very common, not surprisingly, in the southwestern deserts where human populations are sparse. It occurs in the high- and low-elevation deserts east of the greater Los Angeles and San Diego metropolitan areas but is not found in these urban areas themselves. The desert recluse does not live in urban areas where the desert habitat has been converted to green lawns and golf courses, as in Palm Springs. However, if a house is built up

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against a rocky hillside with native vegetation, it will not be surprising for home owners to find desert recluses in their home or garage. One arachnological colleague who lived in Victorville, California (high-elevation desert) never found them in or around his home. If he wanted desert recluses, he had to go out to the nearby desert and look under human-discarded trash or dead cactus. At a University of California research facility in the Granite Mountains off Kelbaker Road (elevation 4,400 feet), the desert recluse was the most common spider found inside the homes of the director and support staff and was frequently found inside the living and sleeping quarters of the visiting scientists. Despite the large number of scientists and students rotating through the facility, no reports of bites were registered. Desert recluses were also abundant inside a home in Yucca Valley, about 25 miles north of Palm Springs, and once again, there were no complaints of bites from the family who shared their living space with them. Texas recluse, Loxosceles devia. The Texas recluse is found in the southern portion of Texas from around Waco south into the coastal area and into Mexico. Big Bend recluse, Loxosceles blanda. The Big Bend recluse occupies the southwestern portion of Texas around Midland and Odessa. Similarly, this species continues south into Mexico. Apache recluse, Loxosceles apachea. The Apache recluse can be found from the western tip of Texas through the southern portion of New Mexico and northern Mexico. Arizona recluse, Loxosceles arizonica. The Arizona recluse has a limited distribution, being collected in a narrow region stretching north and south from east of Tucson to Sedona. Russell recluse, Loxosceles russelli. The Russell recluse is found in the Death Valley area in California and only twenty-seven specimens had been collected from several localities when the species was described in 1983. This spider was named after Findlay Russell, for many decades a renowned toxicologist and physician, who was one of the world’s experts on all animal venoms. Martha recluse, Loxosceles martha. The Martha recluse is found in Whitewater Canyon, west of Palm Springs. Only eight specimens had been collected from three localities when the species was described in 1983. This spider was named after Martha Bogert, wife of well-known herpetologist Charles Bogert, curator of herpetology at the American Museum of Natural History.

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Baja recluse, Loxosceles palma. The Baja recluse is known from areas in the Mojave and Colorado deserts around Twentynine Palms, California. Specimens have been collected in Pioneertown, which used to be a movie set for cowboy movies in the 1940s and 1950s. Other localities where this species has been found are in the mountains and cave mouths between San Diego and Anza Borrego. Tucson recluse, Loxosceles sabina. The Tucson recluse was collected from Sabina Canyon in the Tucson area. Only seven specimens were known when the species was described in 1983. The male has never been collected. Grand Canyon recluse, Loxosceles kaiba. The Grand Canyon recluse is known only from the Kaibab Plateau of the Grand Canyon in northern Arizona. Only three specimens had been collected from two localities when the species was described in 1983.

Recluse Spiders from the Rest of the World About one hundred Loxosceles spiders have been scientifically described throughout the world, and probably a few more will be given scientific names before this book is published. Most of the species are from the Western Hemisphere, particularly Central and South America. The listing here begins with the two non–North American Loxosceles species that have become established in the United States, the Mediterranean and Chilean recluses. Brief descriptions follow of other Loxosceles species native to different parts of the world beyond North America.

Mediterranean Recluse, Loxosceles rufescens This spider was the first Loxosceles spider ever described (in 1820 in Europe) and is the basis for the entire genus. It looks very similar to the brown recluse with a dark violin shape on the cephalothorax, although the pattern is slightly different in outline (Fig. 5.2). Arachnologists who have a lot of experience with recluse spiders can sometimes distinguish Mediterranean from brown recluses just by the violin marking. In order to be sure of an accurate identification of the species, it is necessary to examine the reproductive structures (see Chapter 2). The Mediterranean recluse is known as a worldwide tramp species. It is found on almost every continent. Besides being native to the circumMediterranean countries in Europe, the Mideast, and Africa, it has been collected sporadically in North America, Australia, China, and India; according to older literature, this recluse had not been collected in South America, but

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Fig. 5.2 . The Mediterranean recluse, Loxosceles rufescens, looks very similar to the brown recluse.

it may have become established in more recent times. In North America, it has been collected in many places including Boston, New York, Philadelphia, Harrisburg, Newton, Pennsylvania, District of Columbia, Indianapolis, Cincinnati, several locations in Georgia and Florida, New Orleans, Baton Rouge, Knoxville, Spokane, Los Angeles, Fresno, and San Bernardino. However, most of these finds are of single or a few specimens; once the spiders have been captured or the location treated with pesticide, typically no more are discovered. In the few cases where a population takes hold, a building may have many spiders, but neighboring buildings are typically devoid of the spiders unless they are connected by underground pipes, vents, or passageways. In the District of Columbia, Mediterranean recluses have established populations underground in several buildings on the National Mall. They are also found in the basement of the Smithsonian Institution. In a paper headed up by entomologist Albert Greene, his crew documented the Mediterranean recluse in fourteen buildings, but with only five showing evidence of more than two specimens. In order to put this in perspective and to prevent the typical panic and hyperbole following the discovery of recluses where they aren’t expected, the authors stated that the inhabitants

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of the buildings were not getting bitten, nor did they even realize that the spiders were living in the structures because most of the creatures were in crawlspaces where few people go. Scant numbers of bites have been recorded from the Mediterranean recluse to allow for conclusive assessment, but overall, arachnologists who have worked with it feel that its bite is less potent than that of the brown recluse, although this has never been adequately tested in a side-by-side comparison. Recent research on the Loxosceles spiders in the Mediterranean area using molecular analysis indicates that what is currently perceived as one species may actually be several species. In the future, more species may be described and added to the list.

Chilean Recluse, Loxosceles laeta The Chilean recluse is not found in many places in the United States but has become sufficiently established for small though static populations to survive in a few locations. This is the largest of all the Loxosceles spiders. The males are tan-colored and long-legged as is to be expected of recluse spiders (Fig. 5.3, left) but the females have more of a cinnamon-colored cephalothorax where the violin pattern is somewhat hidden because of the similarity in colors (Fig. 5.3, right). Many species of Loxosceles live in South America but the Chilean recluse is one of the most widespread species there.

Fig. 5.3. The male Chilean recluse, Loxosceles laeta (left), is pale in color and has very long palps whereas the female (right) has a darker cephalothorax, making the violin pattern difficult to see.

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In the United States, the Chilean recluse has its widest distribution in densely populated Los Angeles County, but it is only known from a few locations—mostly in the basements of commercial buildings and never in homes—in a few cities such as Alhambra, Sierra Madre, Monterey Park, El Monte and San Gabriel. It was first discovered in 1967 in Sierra Madre where evidence of spiders including their shed skins was found in 26 of 500 structures. Subsequent searches in Alhambra revealed this species in 70 of 125 buildings, but all were concentrated in a twelve-block area. The nonindigenous spider obviously had been in Los Angeles County for a long time to spread to that extent. However, as buildings were razed and rebuilt, the Chilean recluse did not repopulate the new structures (see Chapter 4), which is consistent with Loxosceles spiders’ inability to disperse readily and colonize new areas. This very circumscribed distribution has taken possibly almost 80 years to come about. The earliest record of the Chilean recluse in Los Angeles was a single specimen collected in 1936, misidentified at the time, and deposited in the Field Museum in Chicago. (Again, this shows the importance of museums and how detective work can add to the story decades later.) Similarly, an infestation was discovered in the basement of the Museum of Comparative Zoology at Harvard University in the 1960s that had probably been there for 20 years; however, inspections of other nearby buildings on campus found no recluse spiders. In order to find them, one almost needs to purposely seek them out these spiders and already to have an idea of where they have been found in the past. In a recent 10-year spider survey by the Los Angeles County Museum of Natural History in which over six thousand spiders submitted by the general public from the Los Angeles area were identified, not one person turned in a Chilean recluse (although many of the people submitting spiders were sure their spider was a recluse of some sort). Loxosceles laeta is considered to be more toxic than the brown recluse spider, probably in part because of its much larger size. Nonetheless, the Los Angeles County Department of Health considers the spider a nonissue because it isn’t living where people live or work, it hasn’t been known to bite anyone in the nearly 80 years it may have been in Los Angeles County, and no one is finding it on a regular basis.

Central America Central and South America are probably the cradle of Loxosceles spider evolution because more species exist in these regions than anywhere else in the world. Forty species have been described from Central America,

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thirty-five in Mexico alone. As one can imagine, not much research has been done on these spiders other than describing them scientifically and giving distribution information. However, L. boneti has been used in venom research.

Caribbean Six indigenous Loxosceles species inhabit islands in the Caribbean such as Cuba, Puerto Rico, the Dominican Republic, Haiti, the Bahamas, the Virgin Islands, and Jamaica. The Mediterranean recluse is also found in the Bahamas and Jamaica.

South America This continent is well blessed with recluse spiders, being home to thirty-six species. Most of the species are not well known, but three (L. laeta, L. intermedia, and L. gaucho) are widespread and cause medical problems over large areas. In Chile, the Chilean recluse is a common house spider, being more often found inside than outside homes. A great deal of excellent Loxosceles research on both biology and medical aspects has been emerging from South America, more so than from anywhere else in the world.

Europe The only currently known species in Europe is the Mediterranean recluse, L. rufescens, which is found in Portugal, Spain, southern France, Italy, Greece, and Crete and nearby islands.

Africa Africa is home to fifteen indigenous Loxosceles species scattered throughout the continent and one nonindigenous species, L. rufipes, from Central America. Six of the species are known from only one location and two others from two locations, with four found solely in caves, including one with an obviously cave-related name of L. speluncarum. Because of the disjunct and widespread recluse spider distribution in Africa, many more species will probably be discovered there. Several species live in South Africa including L. parramae and L. simillima which have dark spots on the edges of the cephalothorax and dark patterns on the abdomen (Fig 5.4), looking very different from the North American species. The Mediterranean recluse is found in the North African countries bordering the Mediterranean Sea.

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Fig. 5.4 . African Loxosceles species are darker than those in the Western Hemisphere and have patterning on the carapace margins and abdomen. This specimen is L. simillima. Photo by Joan Faiola.

Asia Two Loxosceles species are known from China. One species was described from India but it actually was the Mediterranean recluse and the name given to it by an Indian arachnologist was eliminated. The Mediterranean recluse is found in Turkey and Israel.

Australia No native species of Loxosceles exist in Australia although a very minor population of the Mediterranean recluse occurs around Adelaide. Despite significant hyperbole and overreaction, the spiders are not a significant medical concern, especially when one considers all the toxic and potentially deadly organisms (snakes, spiders, octopuses, snails, platypuses, and poisonous plants) already occurring in Australia. For the average Australian, recluse spiders should be low on the list of threatening animal concerns.

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MEDICAL ASPECTS

This chapter could be the most frustrating in the book because a great deal of information is still unknown about the body’s physiological reaction to recluse venom and about its treatment. Understanding of the manifestation of the signs and symptoms of the affliction, and of the underlying mechanism of damage, are still evolving as researchers continue to investigate the effect of venom on both humans and experimental animals. Further confusion is caused by the fact that people’s reactions to the venom vary: some have only minor reactions while others have large wounds or may die. In addition, because many of the early case history reports were based on speculative diagnoses and circumstantial evidence, some were misdiagnoses describing signs and symptoms that had nothing to do with recluse spider envenomation. Subsequent writers replicated the original reports without being able to tell valid from invalid symptomology. All the same, the information here is compiled from hundreds of reported bite cases and review articles on medical aspects of this spider’s venom, reviewed and commented on by the late Gary Wasserman, a pediatric medical toxicologist and brown recluse bite expert who diagnosed over two hundred presumptive cases of loxoscelism. Of course, over the years as medical researchers continue to work on the pathophysiology of brown recluse bites, our understanding may well become more refined and assured. Another source of uncertainty is the fact that some of what we surmise regarding brown recluse bites has been extrapolated from injections of venom into experimental animals, which is grounds for caution because of the differential mammalian responses to recluse venom exposure. For example, mice and rats are often used to determine venom toxicity for

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humans, although they do not develop necrotic skin lesions when injected with brown recluse venom as do humans. Rabbits and guinea pigs develop lesions, but rabbits heal faster and do not develop the long-term necrosis seen in bites in human flesh. Pigs have also been used because of the similarity of pig flesh to human flesh, for example, its relative hairlessness, but pig flesh is thicker and does not have an extensive blood supply as does human flesh. All Loxosceles spiders tested so far contain the venom enzyme sphingomyelinase D capable of causing necrotic skin lesions, and until proven otherwise, it should be assumed that all Loxosceles species are capable of causing some degree of dermal injury. However, differences in virulence of venom toxicity have been reported among the many species. It is not known if these reports are accurate, but if they are, factors causing the differences would include: the amount of venom injected by each species; the toxicity of male versus female spiders; the proportion of the necrotic enzyme in the venom; whether the spider has fed recently; and the time of the year. None of these factors has been sufficiently investigated, but they need further study to confirm qualitative statements regarding species differences in bite toxicity. The information presented here is offered as a summary of the current state of the field. Readers should not use this chapter to self-diagnose a lesion. Diagnosing brown recluse bites is difficult even for physicians. Those without medical expertise are highly likely to make inaccurate diagnoses. People now expect to get quick information via the Internet, and many believe that they can ferret out the recluse as a cause of their problem by matching symptoms—real or perceived—with online descriptions of the results of a recluse’s bite. Many manifestations of recluse envenomation are generic (for example, nausea, vomiting, chills, rash, and fever) and are common to many other unrelated disease states, so it is easy to mistakenly arrive at the conclusion that one’s symptoms can’t be anything other than the result of a recluse spider bite. It would be best to proceed with caution in this regard. Because this book is primarily for a general audience, nonmedical terminology has been used as much as possible. Yet, some medical terms must be used to accurately convey the events that occur after a toxic recluse bite. In many cases, a nonmedical term is followed by the medical term in parentheses, both for readers who wish to become familiar with the proper medical terminology and for medical professionals looking for educational information.

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Fatalities Major damage Serious injury Moderate damage Nonserious injury

Fig. 6.1. Pyramid of car accidents in regard to frequency and extent of damage and injury.

Minor damage Minor injury, if any

When discussing brown recluse spider bites, using the analogy of car accidents will help put in perspective the frequency and likelihood of various expressions of recluse bites in humans. If one considers all automobile accidents, their statistics could be represented by something like the food pyramid, with several layers going from the bottom to the peak, with increasing to decreasing numbers, respectively (Fig. 6.1). At the bottom are the majority of the accidents, which typically involve a crumpled fender or a dent in a bumper. The next level up encompasses fewer accidents in number but with more damage, maybe a smashed window, or the air bag deploys and the occupants get a little hurt or shaken but not seriously injured. The next level up encompasses even more damage to the car and more severe injuries incurred by the occupants, but these events would be less frequent than the level below. Finally, at the top, are the horrific accidents involving massive destruction of the vehicle, and possibly fatalities. These horrific accidents don’t happen often but are the ones that make the news and that people talk about. The analogy of car accidents can be transferred perfectly to recluse spider bites (Fig. 6.2). Most brown recluse bites have virtually no effect (the base of the pyramid), and lesions that do form from the bite are mostly mild and self-healing. Much rarer are horrific large, rotting flesh wounds that do not involve fatalities, and rarest of all (at the peak of the pyramid) are systemic effects involving the destruction of red blood cells (hemolysis), coagulation problems (coagulopathy), the release of hemoglobin into the blood stream (hemoglobinemia), and multiple organ toxicity. Although systemic effects are rare (resulting from fewer

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Mild, self-healing

Unremarkable

Fig. 6.2 . Pyramid of recluse bite probabilities in regard to frequency and extent of injury.

than 1% of recluse spider bites in North America), they occur more commonly in children, and they can be fatal. The latter two types of recluse envenomations are the ones that are trumpeted in the newspapers, on television, and in the medical journals, and because these are the only types of reaction to brown recluse bites that get reported, the entirely false impression is given that this is what happens in the typical brown recluse bite.

Epidemiology of Brown Recluse Bites Brown recluse bites occur when the spider is pressed between flesh and a constraining object; this is a last-ditch defensive behavior in response to being squashed to a point that risks serious damage or death to the spider. Bites happen at night in bed when a sleeper rolls over onto a spider and traps it, or during the day when people are moving furniture or dressing—as when a shoe is pulled onto a foot or when a pants leg, especially of tight jeans, is pressed against a hip, calf, or thigh. Almost all bites occur inside buildings, not outdoors. Brown recluses do not climb through vegetation so lesions received while gardening or sitting on a lawn have a very high probability of being caused by something other than a brown recluse. Brown recluse bites are most common during the summer. In winter, the spider becomes inactive inside of homes, regardless of heating. However, winter exposure to brown recluses is not impossible and may occur when a person unpacks December holiday decorations or puts on a winter coat that has been hanging in a closet for a long time.

MEDICAL ASPECTS

Bites occur most frequently on the legs, then on the arms, and then on the torso. The following numbers are based on 1,581 reports of Loxosceles envenomations by spiders from North and South America: Leg Arm Torso Hand Foot Face Neck Buttocks Shoulder Genitalia

34.8% 16.7% 12.0% 8.7% 5.2% 1.5% 1.2% 1.0% 0.6% 0.6%

The History of Brown Recluse Spider Bites The first known incident of a possible brown recluse bite in North America was reported in 1872 in the Nashville Journal of Medicine and Surgery by a physician named William Caveness. Caveness’s address was Cherokee County, Texas, which is well within the spider’s range so the geography is consistent with a brown recluse bite. The 45-year old patient said that she was bitten by a spider on her thigh, and experienced some of the classic signs and symptoms of severe recluse bite such as sloughing of the skin and a large necrotic lesion, but she also had other manifestations which have never been reported for bites by recluse spiders. However, some of these symptoms may have come from the various types of remedies inflicted upon her. Although the medications applied to the lesion may have been standard protocol for nineteenth-century Texas medicine, this also may have been a case of “the patient survived despite the doctor’s efforts.” These medications included shots of whiskey, morphine, turpentine liniments, and mercury in the form of calomel (Hg2Cl2), the last of which is now considered highly hazardous to human health. The patient did survive and recover. At the end of the report, the doctor speculated that the spider may have been a tarantula. The next known incident attributable to a brown recluse bite was published in 1893 in the Transactions of the Southern Surgical and Gynecological Association by Dr. J. T. Wilson, also from Texas. This paper was written in a somewhat rambling and poetic style (as was common during this era) so it is difficult to assign specific signs and symptoms to the venom of any currently known spider. The physician was apparently trying to describe a black widow

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bite and possibly a brown recluse bite in different patients but half of the bite manifestations listed for one species appear to actually belong to bites of the other species. One of the bites caused a “gangrenous spot” which took months to heal and resulted in the loss of an ear in an 11-year-old girl. Once again, the treatment seems far worse than the disease, with remedies including morphine, chloroform, brandy, ammonia liniments, and a cocaine injection. In 1896, the first case of death likely due to a bite from an unidentified spider was reported by T. E. Presley in the Memphis Medical Monthly involving a 7-year-old girl in Texas. She developed many of the signs now associated with systemic brown recluse bite, including dark urine due to the presence of free hemoglobin molecules (hemoglobinuria), high fever, and jaundice. Once again, the nineteenth-century remedies were appalling. Her death was attributed to kidney failure. In 1929, the first verified recluse envenomation was described by Kansas physician L. F. Schmaus in a case where a woman was bitten on the elbow by a spider hiding in her coat. She developed pain and a generalized rash over her back and abdomen, which then expanded to her legs and arms and was reminiscent of scarlet fever (scarlatiniform rash). She was treated with less barbaric remedies than those above: sedatives along with curative baths and poultices. There is no mention of dire outcome so she probably recovered. After the bite, the dead spider was immediately recovered, was identified by prominent arachnologist C. R. Crosby, and was reported by Schmaus as Loxosceles refuscens [sic: rufescens] although it was most assuredly the brown recluse, Loxosceles reclusa. This seemingly incorrect naming was because the brown recluse was not given its official scientific name until 1940, so Crosby used the most feasible name available at the time. In 1940, another possible case of systemic damage was recorded from a verified bite by a spider in the clothing of a 3-year girl probably from Mississippi. She initially was feverish and had frequent vomiting with swelling on the buttocks where the spider had inflicted the bite. She was sent home from the hospital but returned the next day with a urine sample “perfectly black as if it were ink or as if there was charcoal in it.” The child appeared to be recovering, then collapsed. She responded well to transfusions and intravenous fluids and improved quickly. Eventually, her blood cleared and she recovered completely. It wasn’t until 1957 that a solid association was made between Loxosceles spiders and necrotic skin lesions in North America. Subsequently, many case histories of bites and alleged bites were recorded in the medical literature as physicians attempted to document the extent of damage caused by the spider. As the medical community became more aware of this new health threat, the toxic spider bite syndrome was given the name “loxoscelism.”

MEDICAL ASPECTS

Categories of Brown Recluse Spider Bites It is the ability of the brown recluse spider bite to inflict severe skin damage that gives the spider its reputation. In fact, its bite causes a wide range of reactions in people ranging from very mild events resembling nothing more than a mosquito bite, up to extensive tissue death and scarification. As a result, brown recluse bites are both underreported and overreported. They are underreported because in many instances a recluse bite will not develop much symptomology, the bite victim may not suspect a brown recluse bite, the trauma from the bite resolves by itself, the bite victim does not seek medical attention and the bite is off the medical radar screen. Recluse bites are also overreported because many different medical conditions can result in horrific skin lesions looking like severe cases of brown recluse venom manifestation (see Chapter 7). To prevent such misdiagnoses, it is essential to distinguish between the four main categories of brown recluse spider bites, as follows. Unremarkable bites. The majority of brown recluse bites are insignificant, and people may not even suspect that they have been bitten by allegedly toxic spiders. Wounds are self-limiting: the patient will return to a normal healthy state with general care and without supportive therapy. Bites with minor noticeable effects. With these bites, victims develop signs and symptoms of greater concern, including slight swelling, redness, and pain at the bite site, but no tissue death occurs. Figure 6.3 shows the effect of a bite from a male brown recluse 33 hours earlier: swelling and the right eye closed. It eventually developed into a black eye but healed without problems. In these types of bites, no scarification of tissue occurs and the skin heals nicely without serious complications. Patients with these types of venom expression typically do not seek medical attention, and unless a spider was seen when the incident took place, a brown recluse envenomation may not even be suspected.

Fig. 6.3. This woman was bitten on the cheek by a male brown recluse in Kansas 33 hours before this picture was taken. She sustained only mild swelling and redness, and experienced no necrosis. Image and permission provided by R. Kuypers.

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These first two categories of venom manifestation are the most common outcomes in brown recluse bites, accounting for nearly 90% percent of the results of bites by these spiders. Bites resulting in dermonecrotic lesions. These are the type of lesions most people consider to be the typical reaction following a brown recluse spider bite although in reality, in North America it does not happen in more than 10% of cases (Fig. 6.4). The word is formed from “dermo-,”

Fig. 6.4 . Sixty-five-day progression of a verified brown recluse bite with extreme lesion development in a Missouri patient. Note that the bite victim is obese, which increases the negative effects of the bite because recluse venom has a dynamic detrimental effect on adipose tissue. Bites to thin or muscular people are much less dramatic. Images are from Masters 1998. Copyright © 1998 Massachusetts Medical Society. All rights reserved.

MEDICAL ASPECTS

related to the skin, and “necrosis,” a disease state involving death of tissue. In these events, there is tissue damage, skin cells die, the lesion looks hideous, which can be quite frightening for the bite victim, and heals with scarring. Details of dermonecrotic lesions follow below. Bites resulting in systemic loxoscelism. In very rare cases, a brown recluse bite can cause a very grave condition where the manifestation of the bite is not merely a skin lesion at the bite site. Instead, the envenomation becomes systemic, with potentially life-threatening consequences. In these systemic events, signs and symptoms develop within 24 hours and often do not involve a skin lesion. This makes systemic loxoscelism difficult to diagnose and brings the danger of delay in diagnosis; death can occur within 12 to 30 hours. In the cases where skin lesions occur along with systemic effects, the lesion erupts after the systemic effects begin. Most of the systemic cases involve small children, but adult cases have been reported. Systemic loxoscelism is discussed in more detail below.

Table 6.1. Approximate stages of development of a serious necrotic skin lesion from a brown recluse spider bite Time period following bite Bite 2–6 hours

12 hours 12–24 hours

36 hours 48 hours

3–4 days 5–7 days 7–14 days 2 –4 months

Signs and symptoms May be painless or like a slight pinprick. First signs and symptoms exhibit: mild to severe pain, itching, redness of the skin (erythema), headache, low-grade fever, rash, joint and muscle pain, loss of appetite, gastric distress. A small blister may form, but if there is fluid it is clear or reddened, not containing pus. The lesion may turn from reddish to purplish around the bite. If the redness remains, this is a positive sign that it will not develop into a serious wound; if it turns purplish, this is a sign that tissue death (necrosis) may occur. Skin eruptions that resemble measles (morbilliform eruptions) may form on the trunk of the body, disappearing by the end of the first week. If necrosis is impending, the hemorrhagic discolorations will join together in one big patch; this patch doesn’t turn white when pressed, or if it turns white, it doesn’t return to red when pressure is released; the lesion will be irregularly shaped, not circular or symmetrical in contour. Necrosis typically starts, although it can be as early as a few hours or as late as 14 days post-bite. At the bite site, a scab (eschar) occurs on the top of the lesion. The central area of the wound becomes dark, slightly depressed, necrotic, and hardened; the scab then falls away (sloughs off ), leaving behind an ulcer. Healing occurs.

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Progression of Dermonecrotic Lesions A brown recluse spider bite is typically painless, or the victim might feel a slight pinprick or a nip (see Table 6.1). Almost all of the evident damage is confined to the bite site. Within the first 2 to 6 hours, there may be generic signs and symptoms such as itching (pruritus), mild swelling (edema) if the bite is below the neck, low-grade fever, mild to severe redness (erythema) with bruising, tenderness or whitening of the skin (blanching) as the flow of blood to the bite area decreases (ischemia), headache, joint and muscle pain, rash, loss of appetite and gastrointestinal distress. Pain may increase due to the decreased blood flow and could be severe. Bites to the face or neck can result in significant swelling where the breathing passages may be compromised. The redness may turn to purple (become violaceous) with irregularly shaped margins and a blister (or bleb) may form which contains clear or reddened fluid but not pus; if the area around the wound does not turn purple, the necrotic lesion may not form. A classic brown recluse bite sign is the bull’s eye wound (also known as the target lesion) with a purple or bluish center, surrounded by a larger white ring, which is surrounded by a larger red circle which develops in the first few days. (However, one must be cautious because the bull’s eye wound is also a diagnostic sign of Lyme disease and several other arthropod related events—see Chapter 7.) By day 3 or 4, tissue death (necrosis) may start to occur although it can begin within hours or not until 14 days. At this point, most patients seek medical attention, but for many, this is too late to administer the most effective treatment. By days 4 to 7, a hardened scab (eschar) forms in the middle of a slightly sunken skin lesion and the margins of the lesion spread are determined. The hardened scab may also be delayed by up to two weeks. By days 7 to 14, the scab falls off, leaving an ulceration, which may take 2 to 3 months to heal. For most recluse bites causing necrosis, there is still a good probability that the lesion will heal without significant damage. In cases where severe necrosis occurs, the wound develops a purplish gray color within the first 48 hours, indicating that there will be further damage. This is of special concern if the discoloration does not turn white when pressure is applied, or if it does turn white, does not return to the former nonwhite color when pressure is released. Because recluse venom affects blood flow, bites in areas of significant fat deposits such as the lateral stomach, thighs and buttocks of obese people show extensive skin damage (Fig. 6.4) due to poor blood supply to adipose tissue. The lesion is also subject to gravitational

MEDICAL ASPECTS

flow—if a bite occurs on the thigh, there will be much more lesion formation from the bite site toward the knee than toward the waist. It is not uncommon for a physician to trace around the edges of a wound at daily intervals to monitor the spread of the lesion. Despite tales from the general public and on the Internet, brown recluse bites do not result in amputations. These are likely to be the result of serious conditions such as group A Streptococcus infections (necrotizing fasciitis). Even though brown recluse bites are for the most part medically insignificant, for the rare person who develops a necrotic recluse bite, it is not a trivial matter. It can cause major scarring and the end results can be frightening. However, one must bear in mind that there are far more stories about brown recluse bites than there are actual bites.

Mechanism of Dermatological Damage This is one of the areas where medical researchers are still working on the answers, so the damage process is not completely known. One of the first events in a brown recluse bite is the collapse of the capillaries at the bite site or destruction of the capillary tissue (destruction of endothelial cells lining the blood vessels) which prevents red blood cells from getting to the affected area. This loss of blood flow to the area (ischemia) is the reason the skin turns white. The skin may also be purplish from blood leaking into surrounding tissue, causing bruising. Pain is a common symptom due to the loss of blood flow and the resulting oxygen deficit, and from the direct effects of the venom enzymes. The venom component, Sphingomyelinase D, attacks red blood cells, shredding the membranes and releasing hemoglobin into the blood stream. It also causes activation of the clotting mechanisms whose function is to fix the damaged capillaries, which results in blood clots (thrombosis) at the bite site. The destruction of the tissue at the bite site releases chemical messengers (E-selectin and interleukin 8) into the blood stream which attract specific white blood cells (neutrophils or polymorphonucleocytes). The white blood cells rush to the injury site to try to fight this unknown challenge to the body, which further clogs up the blood flow. These cells also cause their own damage by destroying tissue at the bite site (degranulation). In addition, the release of the chemical messengers (cytokines) may be responsible for an escalation of intense pain due to inflammation, which occurs about 24 hours after the bite. Damage can be within the circulatory system (intravascular) or external to it (extravascular). In summary, capillaries at the bite site are damaged, clots

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form, red blood cells are destroyed, and white blood cells rush in, clogging pathways and causing additional damage. Cells start to die because the supply of red blood cells delivering oxygen has been severely disrupted. An immune response—that currently is not fully understood—also takes place that consists of a complex series of reactions involving a large number of enzymes and chemical messengers inside the body (complement and cytokines). These messengers may greatly contribute to delayed pain. Although early researchers suggested this would lead to little clots being formed throughout the body (DIC—disseminated intravascular coagulation), more recent authors have questioned whether there is enough evidence to consider this an actual venom effect. Another manifestation in recluse bites is the increased production of white blood cells (leukocytosis). Anemia due to massive hemoglobin loss (hemolytic anemia) is a characteristic of systemic loxoscelism (see below). A South American study suggests that mild hemolysis may be more common than previously thought, as patients had elevated levels of some blood components (bilirubin and LDH). Wasserman noted hemolysis in almost all of his two hundred presumptive cases of loxoscelism, including two fatalities (5- and 7-year-olds who died within 24 hours of envenomation from a combination of multiorgan toxicity and bleeding disorder). These two fatalities occurred so quickly after the bites that the typical local cutaneous lesion didn’t develop but rather there was simply a bruised appearance at the bite site. One study investigated additional factors (co-morbidities) correlating with time taken to heal. Some of the obvious factors resulting in longer healing times were lesions of greater severity, and patient delay in seeking medical attention. However, other contributors to longer healing were diabetes and age of the victim (10% increase in healing time for each decade). Predictors of greater scarring were again some obvious conditions including greater severity of the wound and the presence of necrosis. However, increased scarring was also predicted with diabetes and the use of the drug dapsone. A reliable assay for testing whether a skin lesion is a brown recluse bite or not has been developed by researchers but it is still in the experimental stage and not clinically available. It can detect recluse venom in a wound at the level of one ten-millionth of a gram. The assay is known by the highly complicated name of polyclonal antibody-based Loxosceles species enzyme-linked immunosorbent assay (ELISA).

MEDICAL ASPECTS

Treatment of Dermonecrotic Lesions Currently, the preferred treatment for the most common envenomations (those where severe skin lesions do not develop) is the basic first aid of RICE therapy (Rest, Ice, Compression, Elevation)—although cold compresses are preferred over of ice because placing ice on bare skin can cause additional damage from freezing of the tissues. For the more severe lesions where extensive tissue damage develops, removal of the tissue is controversial. In the past, a common treatment for brown recluse bite was the removal of skin early in the development (debridement), which is now frowned on as improper treatment. One of the current strategies is called “watchful waiting,” which calls for not operating on the lesion too early in its development. The late Phillip Anderson, a dermatologist in Missouri who specialized in loxoscelism, stressed the importance of not disturbing the tissue while it was still reeling from the venom assault, and stated that in many cases, it was better to wait until the edges of the lesion are no longer spreading (approximately days 10 to 14). From a different perspective, according to Wasserman, recluse venom stays active in the body for up to 21 days, so that surgical removal before this time may spread the venom to unaffected tissue where incisions are made, and hence it is better to wait 8 to 10 weeks. Either way, medical intervention is recommended when the tissue is already on the mend rather than when it is still being assaulted by the venom and its fallout effects. Indeed, Anderson maintains that the prognosis for brown recluse bite recovery is often quite good with minimal clinical intervention but becomes worse when physicians take a more aggressive approach and try to help the bite victim by operating. According to Wasserman, in cases where a blister of 1-inch diameter develops at the bite site, it is advantageous to remove the blister to rid the bite site of some of the recluse venom so that damage is lessened. Necrosis seems to always occur within the blister margins. Over the years, many remedies have been offered, but there is much controversy over whether these treatments work. Each remedy has its supporters who strongly advocate its effectiveness, but all are uncertain because recluse wounds can heal spontaneously. Because no controlled research has been done where one group of patients gets an advocated treatment and another group does not, there is no statistically reliable test to demonstrate whether or not a particular remedy is effective. In the past, the following have been suggested: antivenom, antihistamines, antibiotics, analgesics, corticosteroids, dapsone, electric shock, hyperbaric oxygen,

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and surgical excision. Here is what is known about the effectiveness of some of these remedies. Antivenom. Although antivenom has been developed, it is most effective within 24 hours of a bite. Because most people do not seek medical attention until about 48 hours later, the antivenom is not widely used in North America. However, a South American study suggested that even in cases where antivenom is given after 72 hours, it still is useful because it reduces the length of hospital stays and speeds up healing even though it does not prevent necrosis. One of the reasons antivenom has not been developed commercially for wide-scale clinical use is that the brown recluse is limited in its distribution in North America and bites are uncommon, so it is not profitable for pharmaceutical companies to spend millions of dollars to produce such a therapy. Dapsone. Dapsone is a drug used to combat leprosy that supposedly works against brown recluse venom by repressing the white blood cells and the immune response in the body. However, in studies with experimental animals, dapsone has been shown to be ineffective. Dapsone has the negative side effect of sometimes causing destruction of red blood cells (hemolysis), similar to recluse venom. An additional severe risk exists if a patient has a deficiency of a particular enzyme (glucose-6-phosphate dehydrogenase or G6PD). If dapsone is given to a person who has a G6PD deficiency, it can result in a condition where hemoglobin is converted to another compound called methemoglobin, which has a lesser ability to capture oxygen molecules. People with high levels of methemoglobin in their body have pale skin and blue lips because of the oxygen deficit, and, low oxygen supply in the body can lead to serious consequences. The combination of hemolysis and methemoglobinemia can be fatal. In addition, the use of dapsone in one study led to significant scarring. Hyperbaric oxygen. Brown recluse bite victims were placed in hyperbaric oxygen (HBO) chambers where they were exposed to high-pressure atmospheres of high oxygen content (well above the 21% normal atmospheric level of oxygen). It was thought that either the high-pressure oxygen was better able to penetrate into the wound and accelerate the healing process or the high level of oxygen negatively affected enzymes responsible for skin damage. Although initial studies showed promise, the use of HBO is currently being questioned as further studies with experimental animals have failed to show any benefit. In addition, HBO is expensive, time-consuming, and available only at specialized treatment centers.

MEDICAL ASPECTS

Progression of Systemic Loxoscelism When systemic loxoscelism occurs (Table 6.2), within 24 to 48 hours the bite victim may experience generic signs and symptoms such as fever, chills, nausea, vomiting, overall tiredness and lack of energy (malaise), headache, weakness, joint pain (arthralgia) and tenderness near the bite site. More diagnostic signs and symptoms appearing at this stage include a rash on the trunk and back reminiscent of measles or scarlet fever (morbilliform or scarlatiniform rash) (though the rash may also be head-to-toe and solid red, especially on the hands and the feet); small purplish spots indicating hemorrhaging (petechial eruptions); yellowing of the skin (jaundice); and yellowing of the eye whites (icteric sclera). The latter two conditions occur due to the presence of a bile pigment (bilirubin) which is normally excreted from the body but may increase due to direct venom effects resulting in toxic hepatitis. Of grave importance, one of the most diagnostic signs is darkened urine. In a systemic reaction to recluse venom, when red blood cells are destroyed (hemolysis), hemoglobin is released into the blood stream (hemoglobinemia) and overpowers the kidney’s ability to fi lter it, leading to renal injury. Hemoglobin becomes present in the urine to such a degree that the urine may be dark brown in color (hemoglobinuria) like a colaflavored soft drink. Anemia is a major concern due to the lack of functional hemoglobin (hemolytic anemia) and typically lasts from 4 to 7 days. This symptom typically develops by the 96-hour mark, but may also occur in up to 8 to 10 days. The free hemoglobin can reduce the kidney’s ability

Table 6.2. Approximate stages of development of systemic loxoscelism from a brown recluse spider bite Time period following bite Bite 12–30 hours 24–48 hours

24–48 hours 2–3 days

Signs and symptoms Painless Death may occur before typical symptoms listed below manifest. Many signs and symptoms develop quickly, including chills, fever, overall weakness (malaise), nausea, vomiting, joint pain, muscle pain, measles-like rash (morbilliform eruptions) that itches (pruritus), small red eruptions on skin (petechiae), yellowing of the skin (jaundice) or eye whites (icteric sclera). A necrotic lesion may or may not develop. Hemolytic anemia begins.

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to filter the blood, resulting in death through kidney failure. There may also be a drop in the blood platelets (thrombocytopenia) as they deposit themselves around the wound or around the body in general, and an increase in white blood cell production (leukocytosis). Development of these signs and symptoms are of much concern although Phillip Anderson was of the opinion that much of the effect of systemic loxoscelism can be remediated by dialysis and hydration. Anderson also estimated that of the one thousand credible brown recluse bites he saw in his 30-year career, less than 1% led to systemic loxoscelism, so it is a rare condition in North America though it appears to be more common in South America with its different recluse species. In any case, because Anderson saw mostly referrals (namely, severe cases sent on to him as an expert by less experienced physicians), the incidence of systemic loxoscelism in North America is in reality much less than 1%.

Treatment of Systemic Loxoscelism This is a potentially life-threatening condition and time is critical. Systemic corticosteroid therapy is suggested for 5 to 10 days to reduce hemolysis, tapering at 3 to 5 days if improvement is noticed. Transfusions of packed red blood cells is recommended, but not of whole blood) because the complement in the latter stimulates destruction of red blood cells (hemolysis). Dialysis is beneficial in protecting the kidneys if kidney failure is imminent because of blood in the urine (hemoglobinuria), but dialysis does not remove the venom. Blood tests to evaluate liver and kidney functions are important.

Recluse Bite Probabilities Because reports of brown recluse bites in the medical literature varied from verified instances with a spider caught in the act of biting to cases where there was no association with a spider except for a lesion that was assumed to be a recluse bite, Anderson devised a categorization of recluse bite probabilities in 1991 which was modified by Rader and colleagues in 2012. The four levels of bite probabilities are based on evidence and are an improvement over much of the reporting of loxoscelism in the early decades where proof was not always convincing. Documented. In these cases, the lesion has at least one of the medical signs of a recluse bite as identified by Rader and colleagues (such as a

MEDICAL ASPECTS

small central blister without pus, a pale area in the center, and gravitational spread of purplish bruising); a recluse spider is captured in the vicinity of the alleged envenomation incident; and the spider is identified by an arachnologist. Probable. The alleged bite occurred within the known distribution area of the recluse spider, the lesion has at least one of the medical signs of a recluse bite, and it has no indication of features of an alternative diagnosis. Presumptive. The alleged bite occurred within the known distribution region of a recluse spider and has at least one of the medical signs of a recluse bite. Putative. The patient has a subjective diagnosis, the alleged envenomation incident is outside the known distribution region of recluse spiders, and the lesion has no features of a typical recluse spider bite. Assigning potential recluse bites to these categories will allow for better reporting so that documented bites will be given more weight and less significance will be attached to alleged bites where evidence is lacking. Minimizing or eliminating speculative reports reduces the chance that incorrect signs and symptoms will be incorporated into the body of loxoscelism literature.

Bacteria and Spider Bites One association that is somewhat well accepted in medicine is that spider bites can cause bacterial infections. This may be yet another one of those pieces of “knowledge” medical people offer in order to explain a skin lesion, but it is not based in solid fact. In contrast, several studies early in this century offer conclusions that spiders are not vectors of bacteria such as Staphylococcus or Streptococcus. Although some researchers have swabbed spider fangs and other mouthparts and cultured several strains of bacteria, this does not necessarily mean that bacteria are transmitted to a person through a bite. In fact, spider venom (as well as venom from other animals such as snakes, bees, and scorpions) is well known to have antibacterial properties, so that these venoms are being investigated for possible use against resistant bacterial strains. The venom in the bite of one Eastern Hemisphere spider species has been calculated to be sufficient to destroy the level of bacteria in its prey. Likewise, although the oral cavities and fangs of rattlesnakes are home to a wide spectrum of bacterial fauna, their bites rarely become infected.

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Phillip Anderson stated that of the one thousand credible bite victims he treated in his career, none developed infection, even those who were not previously treated with antibiotics. A common manifestation of a bacterial infection is pus formation. Brown recluse spider bites are dry except for initial blistering and do not ooze pus. Therefore, if a bacterial infection with resultant pus formation occurs, spider bite is an improbable explanation for the wound.

Brown Recluse Bites Overall With the different categories of bite effects having been presented, the following indicates the frequency of common manifestations in loxoscelism. The result of two studies of signs and symptoms shown by patients with verified bites are presented in Table 6.3. One study examined nineteen Table 6.3. Signs and symptoms expressed in verified brown recluse spider bites in North America Study 1: 19 verified bites Signs and symptoms Pain at bite site Localized itching Fever Localized numbness Rash Chills/sweating Gastrointestinal upset Malaise Nausea Joint stiff ness Sweating Muscle aches Dizziness Headache Difficulty breathing Lesion characteristics Diff used skin redness Early purplish necrosis Swelling Skin hardening (induration) Blister Outcome Necrotic lesion

Study 2: 17 verified bites

10 (53%) 5 (26%) 3 (16%) 2 (11%) 2 (11%) 2 (11%) — 1 (5%) 1 (5%) 1 (5%) 1 (5%) 1 (5%) — — —

14 (82%) 8 (47%) — — 5 (29%) 6 (35%) 5 (29%) 7 (41%) — — — 1 (5%) 1 (5%) 1 (5%) 1 (5%)

19 (100%) 8 (42%) 5 (26%) 4 (21%) —

16 (94%) — 4 (24%) — 5 (29%)

11 (58%)

—

Sources: Data reconfigured from Rees et al. 1987 and Sams et al. 2001.

MEDICAL ASPECTS

patients and the other examined seventeen. The percentages in the table are higher than others mentioned in the text because these are more serious cases, in which bite victims sought medical attention. The mild cases, in which the victim did not seek treatment, are not represented here.

Pregnancy and Brown Recluse Bites In 1991, Phillip Anderson reported in the American Journal of Obstetrics and Gynecology on five cases of loxoscelism in pregnant women. The women were 5-1/2 to 8 months along in their gestation. The cases were handled with conservative treatment and low-dose prednisone as the envenomation signs and symptoms were minor. All had normal births and delivered healthy babies.

Pets and Brown Recluse Bites People often fear that their pets may be harmed by the bite of brown recluse spiders. Veterinarians and pet owners have attributed extensive skin lesions on animals to recluse envenomation, and as with human skin lesions, many of these diagnoses have come from areas of the country lacking brown recluse spiders. In addition, dogs seem to be relatively unresponsive to recluse venom, so a canine lesion is unlikely to be due to a recluse spider bite. In many respects, the brown recluse spider has much more to fear from the companion animals than the other way around. First of all, most pets are covered with fur from nose to tail. This makes it very difficult for a spider of any sort to get close enough to the skin to inflict a bite. Secondly, curious pets are likely to kill and/or eat brown recluses without the spiders doing any damage. In fact, more than one person has suggested that the way to get rid of or at least keep down brown recluse populations inside a house is to own several cats. Also, if the spider is eaten there is such a small quantity of venom (which is a protein) that it should get digested and neutralized in the stomach. As mentioned earlier in the chapter, the reaction of a dog or cat to a brown recluse bite is not necessarily the same reaction as in humans. For example, one of the major problems in humans is the rupturing effect of brown recluse venom on human red blood cells. When tested against brown recluse venom, canine red blood cells are not destroyed by similar exposure to venom. As another example of differential reaction to spider

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venoms in general, the Sydney funnel web spider in Australia is incredibly toxic to humans and other primates, but not other mammals, so dogs and cats are relatively immune. However, with other tarantula-related spiders in Australia, bites to humans resulted in minor injury, but bites to dogs resulted in death, even for dogs in the human weight range (over 100 lb). When brown recluse venom was injected into dogs, they developed poor appetite, dehydration, and apathy, but all the dogs survived and recovered fully within 3 to 5 days. However, these tests were done with intravenous injections whereas a natural brown recluse bite would be made into the skin, not a blood vessel, so that a subdermal injection would be a more realistic simulation of a spider bite. Brown recluse venom can certainly kill dogs, but the researchers had to inject the equivalent of the venom sacs of eight brown recluse spiders before a canine fatality occurred. When less venom was injected, the dogs survived without ill effect. When small quantities of venom were injected into dogs and rabbits, only small, localized lesions developed in dogs whereas in rabbits, full-blown necrotic lesions developed similar to the wounds seen in humans. Therefore, the chances of a dog suffering from a brown recluse bite are extremely small, and veterinarians and pet owners should consider other causative agents such as bacterial infections for their pets’ skin complaints. No venom research is known to have been carried out on cats.

Bites of Other Recluse Species The bites of Loxosceles spiders other than the brown recluse are not well documented in the United States. This is due in part to the urban pest status of the brown recluse which is often found in homes and comes into contact with people more frequently than other Loxosceles species. The remaining recluse spiders in North America are more often found outside homes or are only known from natural landscapes like canyons where human encroachment has yet to happen. There have been a few recorded bites of the desert recluse, Loxosceles deserta, and the Arizona recluse, L. arizonica. The results of these bites have been rather mild in comparison to the brown recluse. Otherwise, bites by native recluse spiders in North America are rare or undocumented. The Chilean recluse has inhabited parts of southern California for over 70 years. Despite its long presence in densely human-populated areas of Los Angeles County, there is yet to be one reported bite by this species in North America, even though it is the largest of the one hundred Loxosceles species

MEDICAL ASPECTS

worldwide and its venom is considered more potent than that of the brown recluse spider. However, in South America, many bites are reportedly caused by regional recluse species with a higher level of systemic loxoscelism and a higher percentage of deaths than in North America. Even though the Mediterranean recluse, L. rufescens, is found sporadically throughout the United States in very specific locations, no reports of bites from this species are known in continental North America. Bites of Mediterranean recluses in the Eastern Hemisphere somewhat mirror those of the brown recluses in North America.

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MEDICAL MISDIAGNOSES

The misdiagnosis of a wound as a brown recluse bite can be just as dangerous as an actual bite. When a medical condition is incorrectly attributed to a bite, that condition may continue unabated and can lead to serious implications and in rare cases, as with actual recluse bites, death. In the mid-1980s, Findlay Russell, one of the world’s foremost authorities on animal venoms and plant toxins, published a few short articles warning the medical community against its tendency to diagnose many skin lesions of varied expression as results of brown recluse spider bites. Working at medical schools at universities in southern California and Arizona, he noted that at least 60% of these diagnoses occurred in areas where no Loxosceles spiders had ever been found. When patients were referred to him for brown recluse bites, more thorough investigation revealed a wide spectrum of conditions that had been mistakenly blamed on the infamous spider. However, after these few publications, Russell’s message was lost in the medical literature and physicians continued to incorrectly diagnose non-spider medical events as brown recluse bites. Around the turn of the twenty-first century, however, a flurry of articles appeared in medical journals reiterating Russell’s message. This resulted from a combination of arachnological research (which provided hard evidence of the presence or absence of Loxosceles spiders in various American states and Canadian provinces) and medical research in nonindigenous areas documenting cases where physicians had diagnosed recluse bites that were later reviewed and the signs and symptoms found to pertain to something other than spider bites. Additional publications examined the historical records of numbers of Loxosceles spiders in these places in comparison to the number of physician diagnoses, as well as to poison control center reports of brown recluse bites in the same areas, and revealed the 113

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spectacular disparity between the large number of diagnoses and reports and the dearth of numbers of Loxosceles spiders (see Chapter 5). One example of the overdiagnosis of loxoscelism is a study headed by I. L. Frithsen and published in the Journal of the American Board of Family Practice in 2007. In a previous study published in 2004, also headed by Frithsen, a survey had been mailed to primary care physicians in South Carolina in which they were asked to report the number of diagnoses they made in the year 2004 involving arthropod-related maladies such as black widow spider bite, brown recluse spider bite, tick bite, Lyme disease, and fi re ant sting. This was the basis for a reanalysis comparing the number of brown recluse spider bite diagnoses to the known occurrence of brown recluses in the state. The authors of the 2007 study (one being an arachnologist from Clemson University in South Carolina) combed the records for all known fi nds of Loxosceles spiders in the state, including museum collections from around the country as well as from publications. The end result was forty-six known specimens of recluse spiders found throughout the history of collection and identification in the state. In contrast, 514 South Carolina primary care physicians had reported 738 loxoscelism diagnoses in 2004. Remarkably, only 19% of the physicians responded to the survey, so if the brown recluse spider bite diagnosis rate for the remaining 81% of the primary care physicians was similar, this would correspond to 3,884 diagnoses of brown recluse spider bites per year. This survey did not include brown recluse spider bite diagnoses made by emergency room physicians or dermatologists, which would have increased the diagnosis total. Even if one only uses the 738 reported bite diagnoses per year as an accurate assessment of recluse presence, the brown recluse spider would be readily known and easily collected in the state. It should be obvious that brown recluse bites are being overdiagnosed in South Carolina. Similar studies comparing the number of brown recluse bite diagnoses to the known number of spiders from the same geographic area were performed for Florida, Colorado, California, Oregon, Washington, and Canada with similar conclusions. Unfortunately, there is something dramatic about spider bites in general and brown recluse bites in particular that causes them to be frequently diagnosed. In discussions with physicians, they readily admit that the diagnosis of “spider bite” is a safe determination because it can neither be proven nor disproven. Additionally, some physicians are not immune from the human tendency to go for an exotic explanation (referred to as a

MEDICAL MISDIAGNOSES

“zebra diagnosis” from the admonition “when you hear hoof beats, think horses, not zebras”). Patients also mislead physicians because they seek medical attention with the complaint of spider bite; since the patient was at the scene of the injury and the physician was not, the physician may take the patient’s word for it. This does not imply that physicians are not doing their jobs correctly. They have a difficult profession: a patient walks into a doctor’s office, can have any disease in the world, and the doctor has to try to figure out what it is and how to heal it. Most of the time physicians provide correct remedies and their patients get better. However, physicians know they work in a world of uncertainty. Various studies estimate physician misdiagnosis rates at around 10–15%. A doctor examining three patients an hour for 8 hours for 5 days, and making a diagnosis for each patient, ends up with 120 diagnoses a week. If the 10% misdiagnosis rate applies, 12 patients per week will have been initially misdiagnosed. Multiplying that estimate by the number of doctors in North America gives millions of misdiagnoses each year. Some of these misdiagnoses will be of brown recluse spider bite, especially when this occurs outside the known range of recluse spiders in North America. Another part of the misdiagnosis scenario occurs whereby a physician may give a patient a list of several possibilities for the cause of a skin lesion when the cause is uncertain. If spider bite is one of the alternative diagnoses, it is more than likely one of the few that a patient can easily remember and pronounce (as opposed to pyoderma gangrenosum or lymphomatoid papulosis) and, therefore, the patient gives the brown recluse spider bite diagnosis greater significance. (Additional aspects of patient psychology are covered in Chapter 8.) By the early twenty-first century, it became possible to draw up a long list of conditions that had been or could be misdiagnosed as brown recluse bites: Infections

bacterial (Staphylococcus, Streptococcus, MRSA, Lyme disease, cutaneous anthrax, syphilis, tularemia, impetigo) fungal (sporotrichosis, aspergillosis) viral (herpes simplex, shingles [herpes zoster]) environmental pathogens leismaniasis

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Circulatory conditions

venous stasis ulcers small-vessel occlusive arterial disease reaction to warfarin Necrotizing vasculitis

leukocytoclastic vasculitis polyarteritis nodosa Takayasu’s arteritis Wegener’s granulomatosis Cancers and related diseases

leukemia lymphoma basal cell carcinoma Topically induced conditions

chemical and thermal burns poison ivy or poison oak self-induced injury Other conditions

other arthropod bites diabetic ulcer lymphomatoid papulosis pemphigus vegetans pyoderma gangrenosum bed sores radiotherapy septic embolism Several of these conditions are highlighted below, with some aspects of their manifestation. This information has been assembled from many sources (for example, Vetter et al. 2003 and Swanson and Vetter 2005), including medical journals, but it should not be considered a replacement

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for advice from medical professionals. It is offered merely as documentation of medical conditions possibly mistaken as resulting from recluse bites. In several of the cases, this information has allowed people suffering from these conditions to get proper treatment.

Medical Signs Excluding Recluse Bite as a Cause In a 2012 paper, Rader and colleagues list a variety of medical signs that are negative indicators of a recluse spider bite. When patients show these signs, some other condition is a more likely cause of the wound. These signs include the following: • • • • • • • •

Pus is observed in the wound (this is more likely a bacterial infection). The center of the wound is raised and red. Fluid drains from a wound during the first week. Lymph nodes are enlarged and tender. An ulcer develops in less than a week. An ulcer is greater than 10 cm (4 in) in diameter or 0.5 cm (3/16 in) deep. There are more than 2 separate lesions except on very rare occasion. The lesion is present for more than 3 months.

This information should be helpful for medical personnel because being able to eliminate loxoscelism as a cause of a wound is just as important as being able to recognize the characteristics of a valid loxoscelism case.

Bacterial, Fungal, and Viral Infections Methicillin-resistant Staphylococcus aureus (MRSA). In the 1990s, an emerging condition involving a bacterial infection became a grave concern in the medical community worldwide: methicillin-resistant Staphylococcus aureus, or MRSA. The condition has been routinely described in newspaper and magazine articles as a dangerous one. MRSA is no more virulent than any other typical bacterial infection but because it cannot be controlled with the usual array of broad-spectrum antibiotics, it often can run rampant even under antibiotic treatment. The mechanism of MRSA resistance is a typical evolutionary one. If the same antibiotics continue to be used in the human population, eventually some bacterial mutants arise, flourish, and multiply even in the presence of this kind of treatment. Eventually, a bacterial infection develops against

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which most antibiotics are no longer effective. This is why physicians don’t prescribe antibiotics on a casual basis (such as for colds which are viral, not bacterial infections) because it enhances resistance. The development of resistant bacteria has occurred almost as quickly as antibiotics have been developed and used. Two types of MRSA occur: hospital-acquired MRSA (HA-MRSA) and community-acquired MRSA (CA-MRSA). HA-MRSA is resistant to more antibiotics because it evolved in and bred in environments where many different antibiotics were used. People who are especially likely to develop HA-MRSA have spent time in the intensive care unit, or have had invasive surgery, intravenous blood hookups, or tubes inserted and left inside them for lengthy periods such as for tracheotomies, mechanical ventilation, Foley catheter placement, and assisted feeding. CA-MRSA is found in communal settings with people housed at high densities such as in prisons, nursing homes, long-term care facilities, barracks, sports camps, and on board ships. MRSA can develop in the staff as well as the inmates or occupants of these facilities. There is also evidence for transmission of a different strain of MRSA between humans and horses. None of these bacterial infections was generated in nature; they are manifestations of antibiotic use and overuse in human environments. A study screening spiders for MRSA by Baxtrom and colleagues demonstrated that spiders are unlikely sources of the infection, not being vectors of MRSA. In an article published by Dominguez in the Journal of the American Board of Family Practice in 2004, among ten Texas patients with MRSA, five were thought to have been bitten by spiders, and another five were believed to have impetigo (a bacterial infection from soil), or furunculosis (boils). Four of the first five were personally associated with six other people who also had lesions that they believed were due to spider bites. In one case, both the patient and the attending physician decided that the lesion was a brown recluse bite. All ten patients had some personal association with prisons as inmates, relatives of inmates, and the like. However, Dominguez showed that all these cases were contagious MRSA bacterial infections, not spider bites. Likewise, in a 2006 study of 11 universitybased hospitals across the United States published in the New England Journal of Medicine, of 248 patients who had their lesions confirmed as MRSA, 29% had come to the facilities with complaints of spider bite. Furthermore, a paper published in Military Medicine in 2006 reported on 23 military personnel with lesions that physicians had diagnosed as caused by spider bites. An arachnologist was sought out for assistance, read the

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details, and suggested a MRSA infection, which was confirmed by further testing. MRSA wounds are typically described as abscesses, with or without inflammation, spreading through the cells or connective tissue close to the surface (cellulitis). The wounds are red, tender, and described as “infected,” “ulcerated,” or “open.” Treatment of MRSA involves better hygiene with more hand washings using antibiotic soap, increased cleaning of bed linens and clothing, and the use of antibiotics such as Bactrim and Clindamycin, to which bacteria have yet to develop resistance. MRSA can be fatal if not accurately diagnosed in time. As more members of the medical community have become aware of MRSA as a common cause of skin lesions, the number of spider bite diagnoses has plummeted. Lyme disease. Lyme disease is very difficult to diagnose. It is known as the “Great Imitator” because it can be mistaken for syphilis, brown recluse bite, and other complaints. Both brown recluse bites and Lyme disease can result in a “bull’s eye wound” with a blue center surrounded by a white ring, which is in turn surrounded by a red ring. In rare cases, Lyme disease can also result in a necrotic skin lesion. The cause of Lyme disease (bacterial infection vectored by a tick bite) has only been known since 1977 and it quickly became recognized as the most common arthropod-spread disease in North America. If left untreated, Lyme disease can lead to irreversible heart and nervous system problems. However, Lyme disease is also difficult to properly assess and many controversies exist over the accuracy of the various tests used to confirm or deny its presence. Edwin Masters, a physician from Missouri, has written several articles on criteria for distinguishing Lyme disease from brown recluse bite (Table 7.1). The best that can be offered here is if a person with a skin lesion lives in or has recently traveled as a camper or hiker to an area known to lack brown recluse spiders but known to have Lyme disease–carrying ticks, one should consider Lyme disease as a possible Table 7.1. How to differentiate between loxoscelism and Lyme disease Signs and symptoms

Loxoscelism

Lyme disease

Nonitching rash starts Pain Shape of wound Gravitational spread Prolonged healing

1–2 days 48–72 hours Irregular Yes Yes

1–36 days None Round No No

Source: Masters and King 1994.

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causative agent. For example, a Rhode Island man who vacationed in Connecticut developed a lesion on his leg. When he returned home, his doctor diagnosed it as brown recluse spider bite. Because the patient investigated and saw that the distribution map of recluse spiders in North America excluded Connecticut, he sought more opinions, which led to a Lyme disease consideration. His first test for Lyme disease was inconclusive but later tests were off the charts for the Borrelia bacteria causing the disease. Traveling through brown recluse territory will not, realistically, result in a spider bite, but people who go on foot outside urban centers in Lyme disease tick areas have a greatly increased probability of contracting the disease. Although coastal New York has Lyme disease, people who spend their entire time in Manhattan have almost no reasonable chance of being exposed to the tick. Group A Streptococcus infection (necrotizing bacterium). In the late 1990s, this vicious infection became well publicized in the news media as the “flesh-eating bacteria.” Group A Streptococcus is indeed a very dangerous condition. It is caused by the same bacterium responsible for strep throat but it manifests in a much more dangerous form. This disease is very fast-acting, spreading quickly through the body, it can lead to amputation of body parts, has a fatality rate of about 20%, and can kill within 10 days. It should be very obvious that in these cases, misdiagnosis as brown recluse spider bite can have serious consequences. Anthrax. In the fall of 2001, bioterrorists sent deadly anthrax bacteria through the mail to several politicians and newscasters. A 7-month-old boy who was crawling on the floor of a television studio in New York City sustained a hideous anthrax infection on his arm. In an article published in the New England Journal of Medicine in 2001, physicians made a preliminary diagnosis of brown recluse spider bite. There are no populations of brown recluses in New York City, although there are few isolated buildings with populations of the Mediterranean recluse, L. rufescens. Although the diagnosis of anthrax was highly unlikely at the time, so was a diagnosis of loxoscelism in New York City. According to Wasserman, anthrax is painless whereas brown recluse spider bite lesions are painful or tender, so that a physician familiar with both conditions would likely not mistake anthrax for a spider bite. Sporotrichosis. This is an infection caused by the fungus Sporothrix schenkii and is acquired from vegetation that scratches people or otherwise punctures the skin allowing the fungus to enter to the body. It forms a necrotic lesion in approximately 20% of cases, mostly on the backs of hands and on the forearms. It is an occupational hazard for landscapers

MEDICAL MISDIAGNOSES

and gardeners, and outbreaks have occurred after Arbor Day celebrations. The infection has been caused by rose thorns, pine seedlings, hay, Eucalyptus cuttings, and sphagnum moss. Because brown recluse spiders are not found in healthy green vegetation, any lesion linked to gardening or compost piles should be considered to be a possible case of sporotrichosis. Herpes. Herpes simplex and herpes zoster (shingles), caused by a viral infection at nerve endings, can lead to skin lesions.

Topical Agents Burns. Both thermal and chemical burns have been misdiagnosed as brown recluse bites. In the case of thermal burns, one woman went to the doctor complaining of repeated brown recluse bites on her back over a series of months. Her doctor agreed with her assessment, although this occurred in the San Francisco Bay area, which does not have recluse spiders. Because of pain from repetitive office work, she slept with an electric heating pad (which is specifically advised against in the owner’s manuals). One night she woke up in pain because the heating pad had slipped out of its protective cover and was burning her wrist. She stopped sleeping with the heating pad and the “spider bites” stopped. A man being treated for a brown recluse bite in the Sierra Nevada region of California tore his house apart looking for the offending spiders. After finding none, he searched the Internet and discovered that brown recluses did not live in his area and also that physicians often misdiagnose the condition. He thought about his activities on the night he developed the lesion and realized that he had been cleaning his oven while wearing shorts and had knelt in a puddle of oven cleaner. In a critical self-experiment, he sprayed a little oven cleaner on the equivalent location on his other leg and immediately melted the hair there, causing a similar wound. He quickly washed off his leg to prevent further chemical damage. This seemingly reckless experiment proved that his lesion was a chemical burn from oven cleaner and not a spider bite. Plant toxins. Both poison ivy and poison oak can be mistaken for a brown recluse bite if they only leave one lesion.

Lymphoproliferative Conditions Cancer. As incredible as it may seem, various cancers have been mistaken for the bites of brown recluse spiders. In one case in British Columbia, a lesion on the back of a patient was diagnosed as a brown recluse bite,

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and the physician identified a spider from her home as a brown recluse. Because no brown recluses have ever been found north of the southern Canadian border and there are several instances where physicians have misidentified common spiders as brown recluses, there was little chance of either the diagnosis or the identification being correct. An arachnologist advised the patient to get a second opinion, the lesion was diagnosed as lymphoma, and the patient started chemotherapy. There are other accounts of melanoma being misdiagnosed as necrotic spider bite in Australia. Basal cell carcinoma has also been diagnosed as necrotic arachnidism. Lymphomatoid papulosis. Lymphomatoid papulosis (LyP) is a rare skin condition considered to be a mild form of cancer that may be related to more serious conditions like anaplastic cell lymphoma. LyP looks like malignant lymphoma but spontaneously heals, which lymphomas do not. It is not fatal but people with LyP have a 5–20% chance of developing serious or fatal lymphomas like mycosis fungoides or Hodgkin’s disease. LyP is a very difficult disease to correctly diagnose, as one needs to confirm it through immunohistological methods. It is also a rare disease so not many primary care physicians are familiar with it. An unpublished study looked at the many misdiagnoses involving LyP. Of 106 people who responded to a survey, only 30 (28%) received no other diagnosis except LyP, although it may have taken several months before it was determined that this was the disease. However, 35 additional people received 45 initial diagnoses involving insects or arachnids for their cancer-like condition. Sixteen were told that they were suffering from the effects of spider bites, with five being attributed to brown recluse spiders, four of which occurred outside the indigenous range of the species. One of the LyP patients had his lesion operated on to “remove the venom to prevent further injury.”

Other Causative Agents Reactions to blood thinners. Blood thinners like warfarin can sometimes lead to skin lesions, for which spiders are blamed. However, once the patient stops taking this medication, the “spider bites” immediately heal and do not recur. Diabetic ulcer. People with diabetes can suffer from poor circulation in the extremities. Because of this, oxygenated blood cannot properly flow into the affected tissues, leading to lesions and at times, amputations of toes. Diabetic lesions have been blamed on brown recluse spider bites.

MEDICAL MISDIAGNOSES

Pyoderma gangrenosum. This disease is fast-spreading and painful, and can cause horrific wounds. Because of the dramatic lesion formation, it is often mistaken for loxoscelism. Although it received its name because it looks similar to gangrene (a bacterial infection), the actual causative agent is unknown, though it is associated with inflammatory bowel syndrome and ulcerative colitis. Treatment has varied tremendously, and as with recluse bite therapy, because there has been no control group, many measures have been tried with no certainty that they really are effective. Although pyoderma gangrenosum can be found on various parts of the body, it frequently occurs on the feet and legs. It appears to be instigated by some minor injury like a bumped shin, paper cut, or possibly even a spider bite. This starts a cascade response in the body and the lesion formation is fast and furious. One critical consideration is that pyoderma gangrenosum will spread faster if surgical intervention occurs. If a pyoderma gangrenosum lesion is misdiagnosed as a brown recluse bite and the physician performs a removal of tissue (debridement), it could actually make the lesion worse.

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HUMAN PSYCHOLOGY AND THE BROWN RECLUSE SPIDER

Rumors are readily spread, myths persist, and people dovelop anxieties and fears. Many features of the brown recluse spider are liable to activate these tendencies. Because they are reclusive, brown recluse spiders are anthropomorphized as insidious and malevolent. The fact that they are nocturnal adds a sinister aura to their doings. If they aren’t evil, why don’t they run around during the daytime so we can see them? Of course, different people display different kinds of susceptibility. The arachnophobe may have an extreme opinion that brown recluses are ubiquitous and highly dangerous because of a predisposition to believe the worst about a creature that induces high anxiety, whereas the average person may merely repeat a newspaper story in everyday conversation. Accordingly, this chapter examines some examples of the wide range of human reactions to the brown recluse spider that have elevated it to infamy.

Arachnophobia People in general have negative feelings toward spiders which vary from mild disgust to full-blown arachnophobia. Some arachnophobes modify their daily behavior patterns to avoid interacting with spiders. They may inspect bed linens before going to sleep, tape the seams around exterior doors of homes so spiders will be prevented from entering, or take their time to get out of the car to avoid seeing a spider (or even worse, having one run across their path). Estimates of intense arachnophobia range from 3% to 10% in Western cultures. Somewhat surprisingly, arachnophobia also exists to a small degree among entomologists; even though these people work with insects, spiders are in an entirely different category in their minds. A California university 125

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entomology graduate student grew up in Missouri and as a child was often rightfully warned about the dangers of brown recluse spiders. However, she also developed severe arachnophobia to the point where she couldn’t even look at a picture of a spider. The presence of a live, moving spider in a plastic bag caused her to immediately run from the laboratory. Another entomology graduate student was highly arachnophobic, avoided therapy because she was afraid that live spiders might be used, and found it unsettling when her family tormented her by using their hands to mimic the slow walking movement of a tarantula. In discussing this apparent paradox, arachnophobic entomologists often realize that their anxieties are irrational—but this constitutes the definition of a phobia. If entomologists can be arachnophobic, this also means that a small percentage of the medical community is more than likely arachnophobic. One can imagine that an arachnophobic physician could easily implicate a spider as the cause of a terrible skin lesion due to this irrational prejudice. The result can be a misdiagnosis. This in turn can lead to the unwarranted development of arachnophobia in patients in circumstances where spider bite is highly unlikely. A patient in Washington State (outside of the indigenous range of the brown recluse) who was diagnosed with loxoscelism developed severe arachnophobia and needed behavioral reconditioning to rid herself of her newly-acquired fear. In another case, a man in northern Indiana (also outside the indigenous range of the brown recluse) was diagnosed with loxoscelism and unfortunately passed away. Several members of his family then developed arachnophobia, two of them with severe manifestations, which was not alleviated until spiders from their house were identified as harmless. The features of spiders in general that make them so feared have more to do with their “spideriness” rather than with the perception of them as dangerous. Some of the common traits arachnophobes dislike about spiders include: their hairiness all over their bodies, their many legs and long legs, and the fact that they run fast, they appear suddenly out of nowhere, they are silent, and many are nocturnal. In addition, their webs are a means of entrapment and feel weird to humans when they rub against human skin. Arachnophobia typically starts around the ages of four to ten. It may be spontaneous or triggered by some incident (for example, turning on a light switch and being scared by a big spider just inches from one’s hand). Young children may see a parent exhibit an exaggerated or fearful reaction to the presence of a spider and then assume that this response is an appropriate one. Arachnophobia has been found to be more prevalent among women

HUMAN PSYCHOLOGY AND THE BROWN RECLUSE SPIDER

than men. It may also have a strong correlation with what are called “disgust factors,” which may be instigated by a basic human disease avoidance strategy evolutionarily developed from the time when primitive humans avoided disease from “disgusting” animals that indicated spoiled food (maggots) or were, and still are, hosts for many human afflictions (snails).

Word of Mouth One of the most common reasons for the persistent perpetuation of the brown recluse spider as a threat occurs because people are much more willing to believe a story from someone they know personally than the informed opinion from an authoritative voice based on solid facts. The personal word of one trusted person such as a plumber, sports teammate, or friend carries much more weight than the knowledge of an expert. Many times an arachnologist living in a nonindigenous Loxosceles area is vehemently contradicted by locals when explaining that brown recluse spiders are lacking in the area. This occurs even though the arachnologist may have collected spiders for several decades in the region and is basing his or her opinion on thousands of spiders collected personally and by students, as well as on hundreds of spiders submitted by concerned home owners and officials who acknowledge that they lack the knowledge to make a proper identification. Many an arachnologist has had the distasteful experience of nonexperts being so adamant in their belief that a spider is a brown recluse or that a skin injury is the result of a bite by one that they demand the arachnologist change information in a publication or on a website.

Belief Bias Such word-of-mouth attitudes are clear examples of belief bias, the psychological term for the condition where even when presented with all available information, some people refuse to budge from their deeply entrenched state of misinformation. We all can think of examples of people forming opinions in direct opposition to mountains of contrary evidence. One of these is people who still believe the planet Earth is flat—that the pictures of our globe provided by NASA are part of a hoax. Similarly, and on a much lesser scale of significance, many members of the nonarachnological public refuse to believe brown recluse spiders are not common everywhere in North America. No matter how much scientific evidence is provided, all it takes is one unsubstantiated story of

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someone finding a brown recluse or one misdiagnosis of a bite to discredit, in the eyes of such people, the collective efforts of hundreds of North American arachnologists who have spent the last two centuries developing the data base upon which the distribution of all spiders in North America including Loxosceles spiders is grounded.

Confirmation Bias If people already have a negative opinion about someone or something, it is very easy for them to believe an additional negative story about the object of their displeasure. In an election campaign, if an allegation regarding graft or immorality is made about a candidate who is despised, the allegation is easily accepted no matter how bogus it might be because it reinforces an opinion already formed. However, if the same allegation is made about a candidate who is liked and supported, it will be tossed aside as a slanderous lie, however well grounded. Because brown recluse spiders are already considered a health menace, any credible story (and even some defying credibility) is accepted and often repeated, sometimes improving in the telling. Tales of brown recluse spider bites have circulated for decades so there is no reason for people to doubt their authenticity. Contrary information (even when scientifically accurate) is discounted as incorrect or as a misinterpretation.

Entertainment Value Scary stories have entertained humans for centuries. Juicy tidbits and gossip about larger-than-life events are embraced and passed on. Horror movies fi ll box offices. Loxosceles spiders, with their “spidery” appearance, their tendency to show up unexpectedly from hidden lairs, and their ability to cause injury, pain, and even death, certainly fulfill several of the requirements for providing a scary story.

The Smoke Detector Principle Randolph Nesse published an article in the Annals of the New York Academy of Sciences on the “smoke detector principle,” also known by the psychological term “catastrophisizing,” whereby any sensation even remotely similar to a major danger triggers an alarm response. This may be a hard-wired survival mechanism. as when seed-eating birds flee in an explosion from a

HUMAN PSYCHOLOGY AND THE BROWN RECLUSE SPIDER

feeder at what seems to be an invisible threat. Even if this is a response to a predator that is only present once in a thousand times that the birds detect a threat, the outcome of a successful predatory interaction is drastic (namely death), so that repeatedly assuming the worst and reacting to minor stimuli are better than not paying attention and ending up as someone’s lunch. Spiders definitively bring out this behavior in humans, especially in parents of young children and owners of pets. Any brown spider is then perceived to be a possible brown recluse and any mark on someone’s body could be a brown recluse spider bite, which could develop into a serious, disfiguring wound. This overreaction occurs in virtually every situation: a spider (whether recluse, widow, or banana spider) is immediately deemed to be potentially deadly when, in most cases, it is harmless or only of minor medical importance. However, once people are educated about the actual distribution of recluse spiders in North America and about the fact that most recluse bites are minor medical events, this education usually (though not always) brings down levels of anxiety.

Fear of the Rare Event The general public reacts with strong fear to reports of brown recluse spider bites, while remaining indifferent to much more clear and present dangers. There are about 30,000 vehicle-related fatalities in the United States every year yet very few people are afraid to drive. Annually, influenza kills anywhere from a few thousand up to an estimated 49,000 during a severe outbreak, yet does one ever hear about a panic to this disease? Even West Nile virus may kill a few dozen to a few hundred people in the United States each year, yet do people get worked up about standing pools of water in their backyard that could be breeding the mosquitos that carry this affliction? More people will die every year from the three conditions mentioned above than brown recluse spiders could ever cause, yet there is no great hyperbole or paranoia associated with them. However, a media report of an alleged brown recluse spider envenomation grips people’s attention and can result in fear of and overreaction to harmless spiders in their homes.

Badge of Suffering In many cases, it can almost be guaranteed that when someone receives a brown recluse bite diagnosis, no matter what the actual cause, this person will be telling the story of his or her encounter with this infamous arachnid

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for years afterward. It becomes a badge of suffering because it is such a noteworthy event. On the other hand, if someone gets a Staphylococcus bacterial infection or diabetes-related skin ulcer, once that person is healed, he or she does not repeatedly retell the story of the experience because no one boasts of merely having an infection. However, if the diagnosis is brown recluse spider bite, with good assurance, the “bite victim” will commonly retell the gory details to anyone who will listen. Once at a brown recluse spider seminar at a college in southern California, an arachnologist mentioned this aspect, and then after listing all the places where the story gets repeated—the grocery store, the bank, the dentist’s office, at school—he facetiously added that “people put this story in their Christmas letter!” which got a good deal of laughter. After the talk, an elderly gentleman approached the speaker to relay a story about his wife’s skin wound that they had thought was a brown recluse bite and asked what it could be. Upon hearing the multitude of possibilities and saying a thank you, the gentleman started walking away, stopped, turned around, and said, “Oh, and you’re right, we did put it in our Christmas letter!”

Shifting Blame An article by Benoit and Suchard in Consultant in 2006 brought up an interesting point about why brown recluse spider bites and generic spider bites are so widely believed in by the general public: people have difficulty accepting that the root of an affliction of theirs is an internal cause that might be considered a weakness. This is even more difficult when it might be some lifestyle choice of the patient that possibly contributes to the problem. Sometimes skin wounds appear as a result of an intrinsic condition such as a virus or venereal disease. Perhaps a lifestyle choice is involved, such as a lip cancer lesion due to chewing tobacco. In such cases, it is comforting to consider that the affliction is not the fault of the sufferers. A spider “attacked” them while they were sleeping. Nothing they could have done would have prevented this accident.

Stickiness In his book The Tipping Point: How Little Things Can Make a Big Difference, Malcolm Gladwell discusses factors causing the rapid spread of fads, rumors, and even epidemics. Among these, in connection with marketing,

HUMAN PSYCHOLOGY AND THE BROWN RECLUSE SPIDER

he mentions the “stickiness” factor. This is something that causes people to want to own a specific piece of merchandise—for example, a minor feature that makes one style of shoe so desirable that many people just have to have it, whereas another similar style can sit on the shelf collecting dust. Brown recluse spiders likewise have a high stickiness factor. People remember stories about them; the stories are repeated. That is a main reason that, in the decades after 1957, the North American brown recluse spider vaulted from obscurity to national and even international infamy. It is amazing how readily the brown recluse stickiness factor has caused the spider to be regarded as a credible source of skin lesions in places like Canada and Alaska. Arachnologists even sometimes receive emails from people in Europe whose doctors consider that they might have been bitten by the spider during a visit to the United States or because they are posted at a US military base that receives shipments from North America.

The Appearance of Credibility One important requirement for the acceptance and perpetuation of rumors is that the information must appear credible. If someone was told of a brown recluse spider bite causing decapitation, that person might wonder how this was possible and after just a little thought would probably dismiss the report as highly unlikely; the rumor would quickly die. However, in the case of a skin lesion, a brown recluse bite may appear feasible. Loxoscelism can involve major injury and even death, yet many more stories are told of these dire consequences than actually happen.

Visibility and Tangibility If a person has a Staphylococcus bacterial infection, the causative agent is microscopic. The physical image of the offending organism is an abstract form and the patient has no visible entity to blame. However, a spider is tangible, concrete, and easy to visualize. Spiders are already well established in the general public’s mind as threats so it is not difficult to finger a spider as a culprit. Unfortunately, this happens too often in the medical world including in publications; spiders have been blamed for causing lesions just because they were found in the same room as a lesion-afflicted person. Another factor contributing to the heightened response to brown recluse bites (and conditions misdiagnosed as recluse bites) comes from the fact

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that skin lesions are visible and sometimes gruesome. If the bite damage was completely internal, the brown recluse would not be so widely notorious. Thus, the black widow spider is common in many portions of the southern United States and its bite, if untreated, is more dangerous than almost any brown recluse bite. About 80% of black widow bite victims who seek medical treatment have reactions that result in moderate to severe symptoms with minor skin changes; widow bites are systemic, causing mostly internal signs and symptoms. In comparison, brown recluse bites are area-specific and visible, yet only about 10% of brown recluse bites lead to serious symptoms; additionally, the presence of a scar adds very nice visual evidence for the blogger or the news reporter’s interviewee. Widow encounters and bites do not make news to the same extent as brown recluse bites. Arachnologists do not see the same amount of hyperbole, fear, urban legend, and word-of-mouth stories associated with the black widow.

Media Sensationalism One of the main causes of the proliferation of brown recluse mythology is the way in which the media reports alleged bite incidents and how the audience responds. In the era from the 1960s to the late 1990s (and even today, though there has been a good deal less sensationalism since the turn of the century), the media reported brown recluse bites because they were indeed news. Venom always makes for an exciting story and readily pulls in the audience as readers or television viewers. Brown recluse bites sell. Press reports of brown recluse bites almost invariably mention that no spider was caught or seen in the incidents concerned. The headlines say “alleged spider,” “possible culprit,” and the like. Although the newspaper may have accurately reported the incident as uncertain, the audience does not retain such words as “possible,” “alleged,” “presumptive,” and “suspected.” When a person is seen on television being led away in handcuffs following a high-profile murder, does the phrase “alleged killer” give the impression that there is just as high a probability of that person’s innocence as of his or her guilt? Probably not. Although a headline may convey less than definitive blame, it is obvious from the amount of time spent in the body of the article describing what happens after a brown recluse bite or the sympathetic tone of the account of the development of the wound that the spider is pronounced guilty without benefit of a trial. This very situation occurred in Ohio when a young prison inmate died and brown recluse spiders were immediately identified as the source of the fatality (Fig. 8.1). However, subsequent investigation revealed that about

HUMAN PSYCHOLOGY AND THE BROWN RECLUSE SPIDER

seventy inmates were suffering from skin lesions that were actually caused by their carving crude tattoos with contraband needles, so that a deadly bacterial infection was being passed around from one prisoner to another. If seventy people in one facility were actually being bitten by brown recluse spiders, hundreds of the spiders would have been seen running around the prison. Another example of this decades-long media hyperbole, is the front page of the Long Island (New York) newspaper, Newsday (29 June 2002), emblazoned with a full-color photograph of a brown recluse spider (Fig. 8.2). New York is outside the indigenous range of the brown recluse;

Fig. 8.1. Headline of a newspaper report on the death of a prison inmate that was initially blamed on brown recluse spiders, and follow-up headline and part of the report stating that the death was more likely due to a bacterial infection transmitted from person to person by contraband needles used in creating crude tattoos. Columbia Dispatch, 1 and 3 May 2003.

Fig. 8.2. Front page of a Long Island, New York newspaper reporting three alleged brown recluse bites in one week. New York is outside the indigenous range of Loxosceles spiders and these diagnoses were surely incorrect. (Newsday, 29 June 2002, Suffolk County edition.)

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only a handful of Loxosceles spiders have ever been found in the state, and the photo is not of a live specimen but is a file photo from an Ohio State University website. In addition to the “Prime Suspect” banner headline and the mention beneath of “possible bites,” the first line of the actual article stated: “In what experts say is a rare if not near-impossible occurrence on Long Island, at least three people have been diagnosed with brown recluse spider bites this week.” The article then reviews the effects of such bites. Although the article quotes entomologists and pest control personnel stating that recluses do not live on Long Island, it also states that physicians contradicted these experts based on their diagnoses. The report led to a wave of recluse spider panic on Long Island for a few weeks. Soon after, as the spider paranoia was abating, anthrax was reported as one of several conditions misdiagnosed as brown recluse spider bites in New York City the previous year, which then set off a round of anthrax hysteria. Then again, in 2013 there were reports that a rock musician had died in the Los Angeles area due to a brown recluse bite. This information was widely reported and arachnologists were contacted for their opinions about the event. However, the chances of encountering a recluse spider in the Los Angeles area, of the spider biting someone, and of the bite causing a fatal reaction are triply unlikely. Several days later, a second article was printed stating that the coroner’s office reported death was actually due to cirrhosis of the liver. The first article was high-profile news in several news sources, the second article with the correction was smaller and less prominent. Recluse bite deaths are sensational and, therefore, news. Death from cirrhosis of the liver is not. Also, when the press reports on brown recluses, it is common for the recluses to be referred to as “deadly spiders” (Fig. 8.3). Think about this for a second. Most brown recluse bites heal very nicely and death is extremely rare. The same newspapers would never publish an article headed “Mother Takes Innocent Children to Soccer Practice in a Deadly Car.” Yet there will be many more vehicle-related fatalities every day than deaths from brown recluse spider bites in a decade.

Fig. 8.3. Press hyperbole: headline warning about “deadly” brown recluse spiders. Louisville Courier Journal, 10 April 1999.

HUMAN PSYCHOLOGY AND THE BROWN RECLUSE SPIDER

In contrast, after a push of research in the early years of the twenty-first century regarding the realities of brown recluse distribution, bites, and misdiagnoses, the media started presenting stories to debunk myths rather than spreading them. Brown recluse spider bites were still newsworthy items and the words “alleged” and “suspected” may still have appeared, but the tone of the reports changed from sensational to skeptical, mirroring the emerging scientific information.

Myths and Dubious Claims Over the years, arachnologists have heard a variety of outrageous myths about spiders. Of course, the brown recluse is a prime candidate for such stories defying logic and biology. Some of them have appeared in works by scientists who were accomplished in their fields but who obviously knew little about spiders. Here are a few examples of myths and dubious claims, with the facts that disprove them. Myth. A man was working on his property and felt a pinprick on his finger while moving wood from a woodpile. He rushed to the hospital and fell over dead in the emergency room. It was surmised to be death from a brown recluse bite. Fact. If a person died suddenly from a recluse bite, it would be because of a heart attack due to anxiety from fear of spider bite, not from the effects of the spider’s venom. Brown recluse venom does not kill adults quickly. As already explained in Chapter 6, brown recluse bites can be fatal but this only happens after many hours, from kidney failure or internal clotting which can be charted with blood tests and urinalysis. Myth. Brown recluses bite people to soften up human skin so their spiderlings can feed off the rotting flesh. Fact. This is pure fantasy. First, no spider uses a vertebrate host of any kind to feed its young. Second, the mother recluse spider requires about 6 hours to make an egg sac. No recluse would take so much time to lay an egg sac on a living, moving creature. Also, brown recluses typically lay their egg sacs in protected spots such as a crevice and stay behind to guard the sac. Third, it requires about a month from the laying of the eggs to emergence of the young—an improbably long time for eggs to sit on a host without being damaged. Myth. Recluse bites cause amputations. Fact. Of the hundreds of credible loxoscelism cases listed in North and South America, not one mentions amputation. As stated previously,

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amputation of limbs is probably a result of a group A Streptococcus bacterial infection. Myth. Brown recluses were brought back from Vietnam in the 1960s by troops returning from war. Fact. Brown recluses are native American spiders. They received their scientific name in 1940 and some of the earliest specimens deposited in museums were collected in Texas in 1903. Dubious claim. A brown recluse bite caused a massive thumb injury (Fig. 8.4).

Fig. 8.4 . Urban legend: these photos claiming to show the progression of a horrific thumb lesion resulting (among other explanations) from a brown recluse bite achieved worldwide Internet fame, although the actual cause was never scientifically determined.

HUMAN PSYCHOLOGY AND THE BROWN RECLUSE SPIDER

Reasons for doubt. This series of photos was widely disseminated through the Internet to warn people about the dangers of a brown recluse spider bite and quickly grew to urban legend status. To date, this same series of photos has been claimed to be (1) a brown recluse bite in seven American states including several (California, Montana, Wisconsin) lacking indigenous populations of brown recluse spiders, (2) a brown recluse bite in four Canadian provinces where the brown recluse is not indigenous, (3) a hobo spider bite in British Columbia, (4) a solifuge bite in Iraq, and (5) an African spider bite in Belgium where added information gives the bite victim only 14 minutes to get to the hospital and states that 88% of victims of an African spider bite lose a limb. So which is it? According to SNOPES.com, an online source investigating and debunking claims, myths, and urban legends, the photos show a real injury to a college professor in Texas, but no proof exists of spider involvement. The patient stated that several doctors diagnosed the injury as a brown recluse bite but that the wound also contained MRSA, the cause of lesions that are often misdiagnosed as spider bites (see Chapter 7). SNOPES.com lists this claim as “undetermined.”

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BITES AND ALLEGED BITES BY OTHER SPIDERS

In the late nineteenth century, there was debate among US entomologists and medical personnel as to whether a small shiny black spider with a red hourglass on its belly could truly be capable of causing horrendous symptoms and death such as were occasionally attributed to it. As information was gathered, the black widow spider became permanently embraced by both medical and popular literature as a creature affecting a person’s health. Once this was established, it was followed by a rash of articles that were meant to educate people about the dangers of this attractive arachnid, but the articles also were full of hyperbole and exaggeration, which also induced fear. Similarly, the brown recluse spider in North America was just another spider until 1957. However, once its bite was established as a cause of necrotic skin lesions, many articles were published in order to warn people of the dangers following a bite. Here too, the unanticipated result was the spread of fear and anxiety. Following on the heels of the brown recluse acquiring an ominous reputation, several other spiders worldwide also came to be suspected of frequently causing skin lesions. This suspicion arose both as a result of experiments exposing research animals to spider venom or inducing bites in their flesh, and out of circumstantial evidence: A person would get a lesion and a spider would be found near the scene of the crime. It is rare to catch a spider in the act of biting, so any unexplainable mark on a person’s body was assumed, without proof, to be a spider bite. After several such incidents, stories circulated in the medical and popular literature. Through urban legend, innocent spiders became scapegoats for all kinds of skin lesions. This line of thinking is very common in the general public and, unfortunately,

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the medical community also sometimes succumbs to such unsubstantiated suspicions (see Chapter 7). Eventually a small group of toxicologists, physicians, and arachnologists started looking more closely at these lesser-known spiders and documenting these rare bites. Data were only collected when a spider was caught in the act of biting and was identified by a qualified arachnologist. This eliminated the circumstantial evidence. What emerged with significant frequency from this verified bite research was that the spiders said to cause skin lesions actually only caused minor irritations that healed within a few days. Non-recluse spiders thought to cause skin lesions are discussed below. The first are the widow spiders, because they are the only group in North America besides recluses that is considered to be medically important. Following the widows are other spiders worldwide that have been incorrectly identified as causing necrotic brown recluse–like skin lesions. Each case emphasizes the importance of conducting proper experimental research and seeking verifiable results.

Widow Spiders Widow spiders belong to the genus Latrodectus, which comprises thirty species worldwide. Many of these species have been well known to the local human populations for centuries as creatures whose bite causes harm. Some of the local names convey this evil reputation, such as “black widow” in English, which also directly translates to the same in French, Italian, Spanish, German, Romanian, and Croatian (in Russia it is the karakurt [“black wolf”]; in the Dalmatia area of Croatia it is the crna baba [“black hag”]). In other parts of the world, the spider’s common name is actually cute and nonthreatening (in South Africa, for example, the several darkly colored widow species are known as “black button spiders”). In any case, not all species of Latrodectus have acutely toxic bites. In North America, two species are the primary causes of latrodectism: the southern black widow, L. mactans, and the western black widow, L. hesperus. Two other native species, the northern black widow, L. variolus, and the red-legged widow, L. bishopi, are not common, are found in natural vegetation, and do not make webs in places where they would often interact with humans, so there is little envenomation threat from them. The brown widow spider, L. geometricus, is a nonnative creature

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which is very common in the southeastern United States and in southern California and has become a major urban pest. Its bite symptoms are usually minor compared to a black widow although some people have had strong adverse reactions. The effects of a widow envenomation are very different from those of envenomation by a brown recluse. Yet on several occasions, patients have informed arachnologists that their physician has made a diagnosis of “black widow or brown recluse bite.” Unfortunately, some physicians have little knowledge of spider bites, and readily turn to spiders as the cause of skin lesions of unknown origin. Widow spider envenomation manifestations are almost completely internal. The venom affects the interface between the nerves controlling muscular excitation and the muscles themselves. In a normal situation, an electrical current races down a nerve and triggers the release of chemical messengers (neurotransmitters) to the muscle, which then contracts. The chemicals are then resorbed back into the nerve ending, the muscle stops contracting, and the system is ready to fire again if needed. It is like turning a light switch on and off with the duration of the “ON” switch being milliseconds. However, black widow venom causes the release of the neurotransmitters in the absence of an electric signal conveyed through the nerve and does not allow the chemical to be resorbed, so the muscle continues to contract. It is like flipping on a light switch and not being able to turn it off. A black widow envenomation results in excitation of various systems in the body. Within 1 to 3 hours of being bitten, a black widow bite victim starts to feel some but not necessarily all of the following symptoms: pain especially radiating through the back, rigid stomach muscles mistaken for appendicitis, localized sweating (so that if the bite is on the hand, only that arm may sweat profusely while the rest of the body is dry), and incessant movement by the patient to try to lessen the pain. At the bite site, the signs and symptoms are very different from those of a brown recluse bite. The skin around the bite turns red, there may be red streaking away from the bite site (lymphangitis), but the wound does not develop a lesion. For many bite victims, a black widow bite feels similar to a bad case of the flu with lots of achiness for about 4 days and then the symptoms recede. Treatment usually involves opiate and nonopiate pain suppressors, benzodiazepines, calcium, and magnesium. Muscle relaxants like calcium gluconate used to be applied, but they were shown to be ineffective and are

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no longer recommended. Antivenom is available and in some cases can bring a patient back to normal within 30 minutes, but there is debate in the medical community in regard to its efficacy. Because the antivenom is based on horse serum, a patient must be monitored for anaphylactic shock. In North America, physicians are hesitant to use antivenom, possibly due to the death of one hypersensitive person who received an improperly administered application. Australian physicians are much more likely to use antivenom because of the positive response and immediate reduction of pain.

South American Wolf Spiders These were the first spiders to be wrongfully blamed for causing skin lesions. The main species involved was originally named Lycosa raptoria but later this name was changed to Scaptocosa raptoria. In the 1920s, many South Americans had mysterious skin lesions that were blamed on wolf spiders due partly to experiments demonstrating that high doses of wolf spider venom caused skin lesions when injected into rabbit ears, and partly to sloppy reporting of skin lesions in patients as having been caused by these spiders. The medical community in South America went so far as to develop antivenom for wolf spider bites and used it for decades. Of course, it didn’t work on the lesions, which caused some physicians to question whether the original information blaming the wolf spiders was correct. Decades later, researchers documented verified bites by wolf spiders, mostly Scaptocosa raptoria. They tallied 515 verified bites where the manifestation of the venom expression was pain and other mild local symptoms of swelling and redness, but none of the bite victims developed skin lesions. As a result, the wolf spider was exonerated as a medically important spider. The lesions were then theorized to have probably been caused by recluse spiders, which were not implicated as the cause of skin lesions until the 1940s. It is possible that wolf spiders were blamed because they are larger, more conspicuous, and run when discovered. In comparison, recluse spiders are very harmless-looking.

Wolf Spiders in Other Parts of the World In general worldwide, wolf spiders (Fig 3.8) have powerful fang and cheliceral musculature so if a spider is large enough and sinks its fangs into skin, the victim will generally feel a painful bite but mostly due to mechanical

BITES AND ALLEGED BITES BY OTHER SPIDERS

damage of fang penetration, not venom toxicity. Wolf spiders actively hunt prey so bites occur when spiders are hiding in clothing. A scenario similar to the South American situation occurred in the fourteenth to eighteenth centuries in Europe with the phenomenon called “tarantism” where spider bites allegedly could be cured by vigorous dancing accompanied by music. This was centered in the town of Tarantos in the Apulia region in the heel of Italy: the dance was called the tarantella, the spider was called the tarantula, and the practice of dancing went on for centuries. (What we refer to as tarantulas are actually mygalomorphs that were named as such by Europeans when they saw large spiders in the Americas. Although the Europeans still refer to their wolf spiders as tarantulas, worldwide the mygalomorph spiders of the family Theraphosidae have usurped the tarantula name.) Although dancing of the tarantella may have been a phenomenon of mass hysteria, another theory is that this is how pagans were able to continue their annual celebrations of Bacchus at harvest time, which involved drinking wine, dancing, and wearing flowers in their hair, among other activities. The Christians came into power and started suppressing pagan activities and rituals. Because people supposedly got swept up into the tarantella frenzy and mass hysteria if they got too close to the dancing, the Christians stayed away and the pagans were then free to continue their celebrations without interruption. There may be some truth to the spider association with tarantism but the bite is more likely to be the work of a black widow than of a wolf spider. Black widow venom does affect the muscles of the body and one of the symptoms of black widow envenomation is that the patient frequently rocks violently and continuously to lessen the pain, so that dancing may have ameliorated the effects of black widow bite. Widow spiders are common in wheat, which was cut and pressed between the left arm and the body at the end of the summer, the same season when the tarantellas were held. Spider bites were occupational hazards for the wheat harvesters, with many bites occurring on the left forearm. Yet wolf spiders were blamed because they were more conspicuous.

Yellow Sac Spiders In the 1970s, many people in Boston complained of skin lesions. Although not seen biting people, spiders were considered to be the source of the lesions. When homes were investigated, the most common spiders found were yellow sac spiders, Cheiracanthium mildei (Fig. 3.14, top). These

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spiders were collected, guinea pigs in laboratories had their backs shaved, and the spiders were pressed into the shaved areas forcing bites. In many of the guinea pigs, necrotic skin lesions developed. The scientists also forced a yellow sac spider to bite a human volunteer which resulted in a minor injury that healed by the next day and did not develop necrosis. The scientists reported this data stating that yellow sac spiders were a “probable” cause of skin lesions but cautiously added that their data were circumstantial. In South Africa, another researcher similarly reported the yellow sac spider in his country as the cause of skin lesions. His declarations were much more confident, though the evidence was still circumstantial. Cheiracanthium lawrencei (now known as C. furculatum) supposedly caused a virtually painless bite, which actually contradicts information on verified yellow sac spider bites, where the bite is described as being as painful as a bee sting, even waking up sleeping victims. The spider also supposedly left a characteristic bite gap of 6 to 8 mm (1/4 to 1/3 in.) between fang marks, although it is actually physically impossible for a spider of such small size to spread its fangs so far apart and still bite. Finally, the South African yellow sac spider bites were said to cause necrotic skin lesions requiring several weeks to months to heal. However, careful review of this research showed no verified spider bites among the cases: none of the spiders was caught in the act of biting and identified by a qualified arachnologist. A second researcher reported that the first researcher had not definitively proved the South African yellow sac spider as a cause of these lesions and presented his data as further evidence incriminating yellow sac spiders. However, this second researcher did not have any verified bites either. A study in 2006 of twenty verified bites by Cheiracanthium spiders from North America and Australia resulted in minor symptoms of mild redness, slight swelling, and itching, all of which resolved in a few days. Similarly, from the same study, of thirty-nine additional cases presented in the worldwide literature where the evidence seemed sufficiently credible to be a verified bite, in only one case did someone develop a pea-sized necrotic skin lesion. In the remaining thirty-eight cases, symptoms were similar to what was presented for the twenty verified bites. Additional cases listed in the literature did not present sufficient evidence of a verified spider caught in the act of biting. Of course, it was in these circumstantially incriminated cases that the most horrific lesions occurred, indicating a very high probability of misdiagnosis.

BITES AND ALLEGED BITES BY OTHER SPIDERS

Hobo Spiders As in many places throughout North America, in the Pacific Northwest in the latter half of the twentieth century brown recluse spiders were blamed for causing skin lesions when the causes of the wounds were completely speculative and there were no populations of recluse spiders in the areas concerned. In the 1980s, the hobo spider, Eratigena agrestis (Family Agelenidae) (Fig. 9.1) became incriminated as a potentially new cause of dermal necrosis in North America. The evidence for this was circumstantial: people who had skin lesions also frequently had hobo spiders in their homes. Hobo spiders were captured, research rabbits had the fur shaved off portions of their backs, hobo spiders were pushed into the shaved rabbit flesh, and the bites resulted in skin lesions. Nevertheless, the deviser of this experiment used “probable” as the first word of the title of his paper and was rightfully tentative about asserting that hobo spider bites were definitely toxic. Once word was disseminated that the hobo spider might be a cause of skin lesions, however, additional papers were published in medical journals declaring that the hobo spider was the cause of these lesions. Similar to the examples of the wolf and yellow sac spiders mentioned above, these additional case histories rarely included a verified bite by a

Fig. 9.1. The toxicity of the venom of the hobo spider, Eratigena agrestis, is currently being seriously questioned with the end result being that it may not be of medical importance to humans.

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spider, nor was a hobo spider actually identified in the incidents concerned. Nonetheless, the medical community and the general public embraced the hobo spider as a causative agent of skin lesions. Newspaper articles reported the dangers of hobo spider bites, medical textbooks included hobo spiders in chapters on animals toxic to humans, and a general consensus was established that if the brown recluse spider wasn’t to blame for an incident, the hobo spider was next on the list of culprits, even though no spider had actually been seen. However a study published by G. J. Binford in Toxicon in 2001 severely challenged the notion of hobo spider venom toxicity. Clean venom was electrically milked from hobo spiders, injected into the same strain of rabbits that had been initially used to implicate the hobo spider, and no lesions developed. Hobo spider venom toxicity still awaits proof or disproof. In the early years of the twenty-first century, a study documented the distribution of the hobo spider as being limited to the region from southern British Columbia to southern Oregon, east to central Montana, and south again to northern Utah around Salt Lake City. At the time of the study, hobo spiders were just being found in Colorado and were later verified in Wyoming, especially in Casper. There is also documentation of a few hobo spiders in one home in New York State but nothing since the original find. In 2012, thriving hobo spider populations were also discovered in Ontario, Canada. There are many parallels between the hyperboles surrounding the brown recluse and hobo spiders. Despite the latter’s distribution being restricted to the northwestern portion of the United States (except for the few circumscribed established listed above), people throughout North America submitted common local spiders as hobo spiders because of the newly generated infamy of this creature. An article in a medical journal stated without documentation that the hobo spider had become the most common cause of necrotic skin lesions in the Pacific Northwest. A critical examination of the published literature, resulting in a 2004 editorial in the Annals of Emergency Medicine, demonstrated that there was only one verified hobo spider bite in a human that resulted in a necrotic skin lesion, this being in a person who did not seek medical attention until 10 weeks after the bite and who furthermore had phlebitis, a medical condition known to cause skin lesions by itself. Hence there is no way to determine whether this wound was due to a hobo spider bite, to phlebitis, or maybe even to both. The only other verified hobo spider bite victim was a dog that was bitten on the lip. All the other

BITES AND ALLEGED BITES BY OTHER SPIDERS

case histories of skin lesions attributed to hobo spiders had only flimsy association with the spider. For example, a person woke up with a red mark on the body and saw a large brown spider in the bedroom. In many of the alleged hobo spider bite reports, the possibility of an actual bite was improbable. For example, the “bite victim” claimed to have walked into a spider web and to have been bitten on the wrist and forearm. Because hobo spiders make their webs close to the ground, it would be highly unlikely (and very comical) to see someone actually walk into a hobo spider web and be bitten on the arm. Yet despite this overwhelming lack of verified evidence, the hobo spider has become well entrenched as a spider of medical importance. A study published in 2014 documented one verified hobo spider bite to a man’s leg where the symptoms were pain and redness with muscle twitching in the calf, with all symptoms resolving in 12 hours. One additional piece of evidence pointing toward incorrect association is that hobo spiders are not known to be toxic in Europe where they are native, and where the study of spiders was under way long before it developed in North America. Because there was, for decades, only one verified hobo spider bite in a human, the symptoms listed years ago as being definite results of hobo spider envenomation were based primarily on circumstantial evidence. However, because several spiders have been wrongly elevated to medical importance by this speculative process, it is currently accepted that such speculation should no longer be the basis for attaching medical importance to spiders. Instead, a series of verified bites where a spider was caught in the act of biting and later identified by a qualified arachnologist should be the defining standard for reliable spider bite data. Although this data is rare and very time-consuming to acquire, it does give a truer snapshot of what occurs in a spider envenomation. Another reason to include a series of bites from the same species is to overcome the problem of single case histories of extreme reaction being published that are then misinterpreted as normal expressions of envenomation. As should be fairly evident, people have historically blamed spider bites for skin lesions without sufficient proof. Hobo spiders might still be responsible for necrotic lesions, but until definitive proof is offered in the form of a series of verified bites by hobo spiders leading to rotting flesh lesions, it is much more prudent to withhold judgment rather than to blame a potentially harmless spider when the real cause may be a medical condition with much more serious outcome.

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False Black Widows False black widow spiders of the genus Steatoda (Fig. 3.11) are in the same family as the black widows, and therefore have a very similar body shape. However, instead of being black, they are chocolate brown or dark purple in color, they never have a red mark on their bellies, and their legs are relatively thinner. Many of them also have tan spots or diamond shapes on their abdomens. The bites of the larger Steatoda species manifest in mild black widow bite symptoms: minor pain, redness, and sensitivity to touch, but symptoms resolve in a few days. Also, black widow spider antivenom appears to be effective on the bites of this spider so there may be some similarity in chemical composition of the venom, or possibly it just has less of the same venom to inject. False black widows are often found in homes so most bites occur indoors when spiders crawl into clothes.

Funnel-weaving Spiders As mentioned in Chapter 3, North American funnel-weaving spiders should not be confused with the Australian funnel-web spiders (genera Atrax and Hadronyche in the family Hexathelidae), which are indeed highly toxic. In North America, funnel-weaving spiders of the family Agelenidae are rarely involved in envenomations, and documented bites by these spiders result in minor symptoms healing without medical treatment. Two verified bites are recorded from the large funnel-weaver Agelenopsis aperta (Fig. 3.2, right) in southern California. A young boy developed symptoms of nausea, headache, pallor, and lethargy but recovered in a few days without incident, and a 54-year-old man was bitten on the finger with minor symptom development. A study published in 2014 documented four additional Agelenopsis spider bites in Oregon with only redness, minor swelling and itching, and in one case back pain. Six verified bites by another genus of funnel-weaver spiders, Hololena, have been recorded. One bite to a finger of a woman had minimal symptom development but two men of robust size were bitten and developed 4-hour periods of vomiting. None of the bite victims sought medical care. A second study involving this genus resulted in three additional bites with redness, two with pain and swelling, and one each with itching and fatigue.

BITES AND ALLEGED BITES BY OTHER SPIDERS

Fig. 9.2. Jumping spiders have excellent vision. This spider is a female Phidippus comatus.

Jumping Spiders Thousands of jumping spider species are found worldwide, mostly being rather small (about 6 mm [1/4 in] in body length), however some grow as large as 13 mm (1/2 in). Their eyesight is incredibly good (Fig. 9.2). A jumping spider can see a person coming and sometimes is not hesitant to bite if a finger is stuck in its face. Bites by the larger jumping spiders are painful at inception, probably due predominantly to fang penetration, but the venom is not especially toxic to humans, resulting in slight redness, tenderness, and minor swelling.

Orb-Weavers Many species of orb-weavers (Fig. 3.10) have caused bites, but most are of minor medical importance in comparison to brown recluse spider bites. Besides the usual manifestations of redness, swelling and, pain, victims have also experienced some but not all of the following: anxiety, nausea, headache, muscle cramps, fever, and numbness. Many species of orb-weavers

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exist throughout the world, which vary in size so that the human reaction to bites in this group will be varied. People get bitten when they walk into webs stretched across wide expanses in their backyards.

Green Lynx Spiders Green lynx spiders (genus Peucetia, family Oxyopidae) are brilliant apple green in color with many spines sticking out perpendicularly from their legs (Fig. 9.3). Although they are most often green, they can change color, adding whites, reds, or purple-browns to their integument in order to match their background vegetation; the process requires about one week. Bites from green lynx spiders are similar to those of many fairly harmless spiders with a little redness at the bite site, however, they possess the unique behavior of being capable of spitting venom a few inches toward a looming face. People who have had green lynx venom shot into their eyes had some discomfort for a few days before symptoms dissipated.

Fig. 9.3. Green lynx spiders have mild bites but they can spit venom about 12 inches and have caused minor eye irritations. This spider is Peucetia viridans.

BITES AND ALLEGED BITES BY OTHER SPIDERS

Woodlouse Spider Woodlouse spiders, Dysdera crocata, (Fig. 3.12) have proportionally large fangs and although they cannot see well, they will respond to the dark image of a human in front of them by opening their chelicerae and holding out their fangs in a menacing manner. Bites by these spiders usually resolve in about 1 hour. Most of the injury appears to be due to mechanical fang penetration.

Parson Spider There are a few recorded instances of people being bitten by parson spiders of the genus Herpyllus (Fig. 3.14, bottom) but the symptoms were mild and disappeared quickly.

Other Spiders Many other spiders are capable of biting humans and causing minor medical injury in North America and around the world. Some of these have low venom toxicity but injury may be due solely to the ability of a spider to puncture human flesh with its sharp fangs.

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CONTROL MEASURES

Because of the concern about brown recluse spiders, many questions are raised in regard to controlling, eliminating, or eradicating them. Pest control experts who work in areas where Loxosceles spiders are indigenous believe that complete eradication is difficult. The best success most people can hope for is a reduction of the population to the point where it is rare to encounter a recluse in the home. Works providing information on spider population management are listed in the references at the end of this book, but it is probably best to leave the control methods to pest management professionals. These professionals will know the most current and effective procedures. However, do not expect total victory over brown recluses in a treated structure forever. If a structure has lots of nooks, crannies and crevices in which to hide (as all houses do), it will be difficult to apply sufficient pesticidal measures to completely destroy the entire population. Control of recluses requires constant vigilance and continual pesticide applications to keep these reclusive critters under a threshold level of nuisance. It is important to remember that although brown recluse spider bites do happen and, in rare cases, can cause significant medical problems, millions of Americans in the Midwest are currently sharing their homes, although maybe not happily, with millions of recluse spiders without incident. Yes, the brown recluse spider can be a nuisance, but many testimonies from people in indigenous recluse areas will admit that the spiders are not of great concern to them. Families can live for decades in a particular home and raise a generation of children without brown recluse spiders being a major issue or a major source of medical injury. Brown recluses should not be ignored, however; a little awareness can go a long way in minimizing risk of envenomation. 153

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Besides the medical aspects, another area where brown recluses can cause major headaches is in real estate. With disclosure laws and inspections of homes for sale, a house infested with brown recluses may be a difficult sell, especially if the prospective buyer is moving from an area of the country that does not have these spiders. The only awareness this potential buyer may have about brown recluse spider bites is from all the horrific, frightening (and often bogus) stories of people losing limbs and dying. If a brown recluse population is disclosed to potential buyers with infants, children, or pets, fear of a spider bite is amplified.

Positive Identification The first step in controlling brown recluses is to make sure there is positive identification of the spiders on the property concerned. This may seem like a waste of time in places like Kansas and Missouri where brown recluse spiders are extremely common. It is not unusual for homeowners in indigenous areas to be very capable of correctly identifying a brown recluse. However, not every home in Oklahoma or Arkansas has brown recluse spiders. If you live on the edge of or outside the range of recluse spiders shown in Figure 5.1, then there is a strong probability of spiders being misidentified as recluses. More than once, a homeowner has called asking for advice on how to eliminate brown recluse spiders, and eventually, it has become apparent that the spiders involved are not recluses. Besides the presence of the spiders, other evidence of recluses can be obtained from the shed skin (Fig. 4.18). The skin’s star-shaped pattern can usually be found on vertical surfaces. The recluse shows site fidelity: it is not uncommon to find multiple shed skins of increasing size in one spot, indicating the repeated return of the spider to the same retreat as it was growing.

Brown Recluses in and around Homes Brown recluses are fond of cracks and crevices. Recluse spiders have been shown to prefer retreats of vertical rather than horizontal orientation, with sharply angled rather than smoothly curved interiors, and with silk left behind by previous recluse spiders. They also have been shown to prefer rough surfaces such as wood, cardboard, and unfinished ceramic to smooth surfaces such as slick metal, finished ceramic, or plastic, although they can be found on corrugated metal.

CONTROL MEASURES

Outdoors, brown recluse spiders take up residence under items like loose bark on trees, stones, firewood, piles of bricks or cinder blocks, doghouses, decks, hot tubs, and piles of debris or bricks. False shutters are a favored place to take shelter although the spiders are much more common inside structures and it is rare to find them outside. Although the saying “never say never” may apply, brown recluses are not found in live vegetation such as grass or ivy or the plants of a vegetable garden although they may be under ornamental stones or bricks lining a garden pathway. Indoors, brown recluses inhabit attics, basements, and crawl spaces, and are often found in greatest abundance behind tar paper, under attic insulation, in corners, and next to ceiling joists. In living areas, they are common behind bed headboards, in the folds of curtains, on the undersides of sofas, in kitchen and bathroom cabinets, behind sinks, in between pages of newspapers, and under doorjambs and window sills, among other places. In garages and barns, brown recluses seek out crevices in folded tarps and under the folded-down flaps of cardboard boxes. Home age does not seem to have much significance. Older, infested homes appear to have brown recluses throughout the structure whereas newer homes have infestations isolated in specific areas. The type of roof may affect recluse populations. Roofs with plywood backing and an underlayer of moisture repellents offer fewer acceptable places for recluse spiders to establish themselves than do shake-shingle roofs with gaps between the boards and “skip decking” (wooden laths with large spaces in between to which shingles are nailed instead of a continuously solid wood foundation). However, one expert states that each home is going to be unique and should be considered on an individual basis because homes with basements present different problems than homes with crawl spaces or those on concrete slabs or cinder blocks.

Control Measures for the Homeowner Sticky traps or sticky boards are frequently used where brown recluses are roaming (Fig. 10.1). However, pest management professionals disagree regarding their effectiveness. One camp advocates using as many sticky traps as feasible because every spider caught is one less spider roaming around the house. Dozens of the critters were collected in one sticky trap in 24 hours under a couch that was being used every day. However, a contradictory opinion is that sticky traps give the homeowner a false sense of security. Sticky traps predominantly catch males that are wandering

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Fig. 10.1. Sticky trap with at least forty-eight brown recluse spiders from Columbia, Missouri.

around looking for females, although some females do indeed get trapped. The females do not wander as much as the males so they stay behind the tar paper and continue to pump out egg sacs that replenish a house’s population. This continual supply of spiders coming from behind the woodwork means that numbers will never actually be brought under control with sticky traps alone; more comprehensive treatment is needed. Sticky traps can be very useful for verifying the presence of recluse spiders and they indicate of the degree of infestation, which areas of the home are most heavily infested, and where it might be best to focus attention. Use of these traps may also give an indication of what features of a room are conducive to encouraging or discouraging recluse populations, and this may provide an avenue for reducing numbers in heavily infested areas. Sticky traps come in different designs. The type used depends on the situation. If there are no nosy pets or curious children, flat traps are useful as all the spider has to do is run across the trap in order to be captured. However, if pets and children are present, triangular tent-shaped traps with openings at the end enclose the sticky surfaces (Fig. 10.2) and might be a better choice, although the spider has to crawl inside the trap to get caught which is less likely than its running across a flat trap. If sticky traps are deployed, they should be placed against walls and under furniture. Brown recluses will stay close to walls or at the least, they will follow a wall while moving. In addition, a sticky trap placed in the

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Fig. 10.2 . Triangular tent-shaped sticky trap.

middle of the room is very inconvenient and not very aesthetically appealing. Traps should be placed in cabinets, under sinks, under bathtubs of a free-standing type on legs, behind the toilet, and in closets on the floor and up on the shelves. In attics where human and pet traffic is minimal, the more traps the merrier. In the garage, traps should be placed behind items not frequently moved as this will prevent their being accidentally stepped on. Traps should be replaced as they get fi lled up with spiders or covered with dust. Some people go one step further by placing sticky traps under each leg of a bed so that if a spider moves toward the leg, the trap will intercept it. The daughter in the highly infested house in Lenexa, Kansas, did this, and she was indeed able to trap several recluses. Parents of infants may also want to try something similar under the legs of a crib or basinet as an extra safety measure. Placing an object such as a little disk of cardboard or rubber on the trap before lowering the bed onto it will prevent the sticky material from getting on the bed legs. Home improvement and hardware stores may even sell little coaster-like discs with carpeting on the bottom for placement under furniture to prevent scratches on wood floors. Some thought should be given to preventing the bedding from falling into the

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sticky material, which is easy enough with a crib where the blanket will stay inside, but not so simple on a normal bed where a slipping blanket can get stuck and ruined. A possibly simpler and cleaner preventative measure is to wrap double-sided sticky tape around each bed leg. Obviously, traps should not be put in routes of foot traffic where they can get stepped on. Of course, traps need to be hidden very well to prevent a toddler wearing a sticky trap like a graduation mortarboard, or a dog happily wagging its tail with a trap fanning the air. If sticky traps are deployed around children or pets, it might be advisable to keep on hand a supply of the items capable of removing the sticky adhesive. Searching the Internet for “remove sticky trap glue” results in several websites that offer choices of removal agents. Depending on whether the surface is your carpeting, a dog’s tail, or a baby’s head, the choices vary among vegetable oil, WD-40 lubricant, and Goop hand cleaner, to name a few. One website lists liquid dishwashing detergent, hand creams, rubbing alcohol, and peanut butter as effective substances. Additional control methods for the homeowner include the use of a vacuum cleaner with a hose attachment to effectively remove spiders. If a regular vacuum cleaner is used, it might be best to remove the vacuum bag when done, seal it with tape, and for good measure, put the vacuum bag in a plastic bag which is then securely fastened before throwing away outside just in case the tape falls off while in the trash. If a shop-vac is used, there may be little need to dispose of the contents; in a South American study, just the tumbling inside the hose and the force of the vacuuming was sufficient to kill recluse spiders in almost all life stages. Also, a strong black light used in a dark area like the attic will help locate the egg sacs which shine brightly and then can be scraped off with a putty knife.

Control Measures for the Pest Management Professional If a house is extremely infested, it will be best to call in a pest management professional. In the reference section, several works intended for pest control personnel are listed. Because these involve the use of pesticides, qualified personnel should perform the application because they have training in the proper method of deployment and also have the necessary licenses for the legal application of chemicals. The homeowner needs to be aware of one very important aspect of brown recluse control: it will require multiple visits and a vigilant attitude. This is not a situation where a pest control professional can make one visit, wave a magic

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wand (even if the magic wand is emitting pesticide), and make all the spiders disappear. One expert recommends four treatments a year: in February–March in order to get to the egg sacs about to hatch; in May–June to attack the spiderlings, which are vulnerable to liquid sprays, knocking down the population before it can build up; in August for general control; and in October– November with crack and crevice treatments and behind false shutters to attack the spiders as they are settling in for the winter. The pest management professional should not try to eradicate everything at once because the different stages of spiders (egg sacs, spiderlings, wandering males, sedentary females) require different approaches, and sometimes different treatment. The overall procedure is crack and void treatment. Residual insecticide dust is long-lasting and is a desiccant that causes water loss in the spiders and eventual death. Residual aerosols provide quick knockdown but are short-lived. One publication encourages use of liquid sprays on the spiderlings as it has immediate effect. Compounds such as deltamethrin and beta-cyfluthrin are effective. Spot treatments are ineffective on their own but are used to supplement larger-area application. Pesticide should be applied to cracks and crevices. Electrical plates should be removed from walls and pesticide applied into the wall voids, with a plastic tip on the applicator to avoid electrical shock. Holes may need to be drilled into walls in order to apply pesticide into other voids. Crawl spaces and attics should be treated, and because these are confined spaces, this is truly why only professionals should handle this activity. In attics, attention should be focused on light fi xtures and vents as recluse spiders use these pathways to transit from attics into living spaces. If recluses are in insulation, this should be lifted and application made underneath. This is very timeconsuming but applying insecticide only on the surface will be ineffective. Treatment should focus on the walls as the spiders do not often run around through the open space in the middle of a room. One anomaly of pesticide application is that it may cause an increase of spider activity for the first seven to ten days after application, because the spiders have had their nervous systems irritated or poisoned at a sublethal level, causing them to behave differently from usual. Although a homeowner may request the labor-intensive and expensive technique of fumigation of an entire house, this may result in only a temporary decrease in population. In one study, sulfuryl fluoride fumigant killed all exposed brown recluse spiders when applied at 1.7 times the standard rate for controlling drywood termites. However, egg sacs of

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many arthropods are typically better protected than the adults, hence, they require more fumigant and may survive to repopulate the structure. Another procedure often used by the pest control industry is ultra lowvolume (ULV) pesticide application, which is most often used against free-flying pests in confined spaces but is not highly effective for spiders. After a pest management professional has gotten a brown recluse spider infestation under control, the typical reaction of the homeowner is to cancel the contract with the pest control company. However, the brown recluse population may build up again so that the entire cycle starts all over. Subsequent control after the population decreases may not require four or five visits a year as when populations are rampant. It makes good sense to maintain a contract with the pest control folks and have them return to monitor the situation to determine if the number of spiders is increasing again.

Reducing Chances of Encounters and Avoiding Bites Although someone who lives in a structure with brown recluses may not be able to do his or her own pest control, the average person can do many things to minimize the chances of an encounter with brown recluses—a matter of great interest to parents with small children. The measures listed here should only be pursued by people who live in indigenous Loxosceles areas and who have proof of these potentially dangerous spiders in their homes. Again, there is no reason to waste time and money trying to recluse-proof a house unless an infestation has been verified. The identification of the spiders should be made by a qualified person, preferably an arachnologist or an entomologist with sufficient arachnological training, although this is not always feasible. The typical recluse envenomation scenario occurs when a Loxosceles spider is pressed between flesh and some other object, and the spider is experiencing a near fatal crushing. Therefore, reducing the probability of encounters will be highly beneficial. Many people in indigenous recluse areas already take most basic precautions such as banging out shoes left lying on the floor or shaking out clothes before putting them on. It may be an inconvenience to do this every day, but it may prevent a bite. Because recluse spiders are nocturnal, a bed is one of the more common places where a bite can occur. Activities to reduce this type of encounter include moving the bed away from the wall, making sure the blankets do not reach all the way to the floor, getting rid of bed skirts or ruffles on the

CONTROL MEASURES

bottom of the box spring, and not using the underside of the bed for storage. If all this is done, the only way for a spider to get up on to the bed is to crawl up a bed leg (unless one of the methods described above is used). Another safety precaution is to pull back the covers and inspect before getting into bed. Luckily, Loxosceles spiders are not likely to fall off ceilings to inflict injury in a kamikaze dive on to a sleeper below. In the home and especially in closets, as much clothing as is feasible should be kept in sealable garment bags. Shoes should be kept in plastic shoeboxes. Sweater boxes are useful to exclude spiders from other clothing. This is especially important for seasonal clothes that sit for long periods of time without being used—such as winter clothing, as these garments are put away during the summer when the spiders are most active and may crawl into sleeves. Some sources recommend removing clutter in order to reduce recluse populations, however, an equally important benefit of clutter reduction is that the fewer objects there are inside the home, the easier it is for a pest control professional to properly treat an area. In the garage or basement, any item of clothing or sports gear worn on the body (for example, a baseball glove, roller skates, hockey gear, ski clothes and gloves, gardening gloves, shirts, and aprons) should be stored in large spider-proof bags such as those with zipper locks; these now come in 10-gallon sizes just for this purpose and may be available at a local hardware store. This will surely keep the spiders out. This is particularly important for clothing not worn for many weeks or months. If clothing is not stored in bags, it will be well worth the effort to shake out and stomp on gloves and gardening shirts before putting them on. If December holiday decorations are removed from an attic or basement in a region of the country where the outdoor temperatures are below freezing, storing the boxes outside in an unheated shed or garage during subfreezing periods before unpacking may kill off some spiders. Boxes of decorations taken inside should be carefully inspected as the contents are removed. It might be wise to have a vacuum cleaner plugged in and ready to suck up any escaping spiders. If it is above freezing and not too cold for humans, it might be advisable to unpack such boxes in a large open area like the middle of a garage so that if a spider is awakened from its winter hiding spot, it will be seen crawling away in an area where an escape poses less of a threat to the home occupants. Also, as boxes of decorations or winter clothing are put back into storage, all edges should be sealed with tape so that brown recluses cannot crawl inside during the summer. Boxes in storage should be placed 8 to 10 inches off the ground and the same

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distance away from walls to avoid producing the tight spaces that are recluse-friendly habitat. Wood for fireplaces should not be stored next to the house where it might provide a harbor for spiders and give them a base camp from which they can move inside. Be careful when bringing wood into the house and allowing it to sit for a while to warm up to house temperature—at which point spiders could be liberated. It might be best to leave the wood outside until the fire is being started, or to place the wood somewhere such as the garage, where if spiders warm up and run out, it will be less exciting. Reduce the amount of clutter outside the house for the same reasons—piles of debris, bricks, cinder blocks, shingles, and so on. Move the doghouse away from the house unless this increases the discomfort of your pets. Most recluse spiders come from inside the home, not reinvading it from the outside. Nonetheless, making the house less “leaky” will prevent insects that serve as spider food from getting inside. Seal visible cracks and crevices on the outside of the home. Check openings for electrical wiring and plumbing that might allow access. Use expandable foam or caulking to seal the breaches. Architectural apertures such as the weep holes in brick veneer and the air vents leading to the attic, however, are crucial for necessary ventilation and should not be plugged. Instead, they should be covered with screen of very small gauge, as spiderlings can walk through tiny openings.

GLOSSARY

abdomen The hindmost major body part of the spider, which contains the heart, digestive organs, and silk-producing glands. arachnidism Medical consequences due to an envenomation. araneomorph A spider suborder that is evolutionarily specialized and has opposable fangs (that work like pliers). The brown recluse is one of many araneomorph spiders. autotomy The act of shedding a body part—in the case of spiders, a leg. cardiac region The area on the dorsal surface of the abdomen near the cephalothorax. cephalic region The head region of a spider, which contains the eyes. cephalothorax The frontmost major body part of the spider on which the eyes are located and to which the legs are attached. chelicerae Movable mouthparts of the spider to which the fangs are attached. coxa The first of seven leg segments, very short and located next to the body. cribellate A group within the araneomorph spiders in which the spinning organs are characterized by a special flat spinning plate with many silk spigots. The brown recluse is not a cribellate spider because it does not have this special plate. See Ecribellate. dermonecrosis A disease state that involves the death of the skin; one of the manifestations of severe brown recluse bite. dorsal The top side of an animal, usually the back. See Ventral. ecribellate A group within the araneomorph spiders that does not have a special silk spinning plate. The brown recluse is an ecribellate spider. See Cribellate. embolus The slender saber-like structure of the male mating organ, which is inserted into the female reproductive opening. entelegyne A spider group within the araneomorphs that is evolutionarily specialized and typically has complex reproductive organs. The brown recluse is not an entelegyne spider. See Haplogyne. 163

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GLOSSARY eschar A hardened ulcer that forms in a lesion following a severe brown recluse bite. femur The third of seven leg segments, the long leg segment closest to the body. haplogyne A spider group within the araneomorphs that is evolutionarily primitive and has very simplistic reproductive organs. The brown recluse is a haplogyne spider. See Entelegyne. indigenous Describes the natural area in which an animal lives without influence from human movement. instar A stage between hatching and molting or between two molts, or an individual arthropod in such a stage. The first instar occurs in the egg sac and is the period between hatching from the egg and the first molt. The second, third, fourth, and subsequent instars represent the periods between successive later molts. ischemia The temporary lack of blood flow to an area. This is a sign of a brown recluse bite. loxoscelism The medical syndrome resulting from a brown recluse spider bite. monochromatic Of a single color, as the brown recluse’s abdomen or legs. mygalomorph A suborder of evolutionarily primitive spiders, typically large and thick-legged. Tarantulas are mygalomorphs but brown recluse spiders are not. necrosis Death of body tissue. necrotic Adjective that describes dead tissue. Necrotic wounds sometimes happen after brown recluse spider bites. necrotic arachnidism The term for tissue death of skin that is caused by spider bites. palps Sensory appendages in the front of a spider’s body between the chelicerae and the first pair of legs. Pedipalps (as they are also called) are composed of six segments whereas legs have seven segments. In female and immature spiders, the pedipalp looks like a scrawny leg. In the male, the terminal segments of the pedipalp develop into the mating organ. pedicel The narrow connecting conduit between the cephalothorax and the abdomen. pedipalps See Palps. poikilotherm An organism that cannot regulate its body temperature and whose activity is typically curtailed in cold weather. Spiders are poikilotherms. posterior Toward the back end of the spider. procurved A line that curves toward the front of the body, usually used in reference to eyes though not for those of the brown recluse. See Recurved.

GLOSSARY recurved A line that curves toward the back of the body. The six eyes of the brown recluse are recurved, making a U-shaped line facing toward the abdomen. See Procurved. sclerotized Term for a hardened body part, such as the fang or the female spider’s reproductive organs. stridulation The sound made by spiders by rubbing a hardened pick or peg on the palps over a series of ridges on the chelicerae, used in mating behavior. synanthrope An organism that increases its population in association with humans. tarsus (plural: tarsi) The seventh and last segment of a spider leg, farthest away from the body. taxonomy The field of biology that involves the naming and sorting out of species. trochanter The second of seven leg segments, found between the coxa and the femur, which is small and not easily seen. uncate Term describing fangs that have an accompanying spike or spine; the tips of the fangs and spine touch. Such fangs look like the pincers of a crab. Brown recluses have uncate fangs. ventral The underside of an animal, the belly side. See Dorsal.

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In this section, literature is listed under each chapter heading in case the reader wishes to seek out specific articles that were the basis for the information in that chapter. Almost all are scientific or medical publications and may not be easily obtained by the general public, although some are available for free online from the journals concerned, especially if they were published many years ago. The works listed are primary sources, not secondary interpretations of research, which would make them redundant in view of the information provided in this book. Some of the articles are listed more than once as their content pertains to several chapters.

1. Taxonomy Cameron, H. D. 2005. An etymological dictionary of North American spider genus names. In: Spiders of North America: An identification manual, ed. D. Ubick, P. Paquin, P. E. Cushing, and V. Roth, 274–330. Poughkeepsie, NY: American Arachnological Society. Gertsch, W. J. 1967. The spider genus Loxosceles in South America (Araneae, Scytodidae). Bulletin of the American Museum of Natural History 136: 117–174. Gertsch, W. J., and F. Ennik. 1983. The spider genus Loxosceles in North America, Central America, and the West Indies (Araneae, Loxoscelidae). Bulletin of the American Museum of Natural History 175: 264–360. Gertsch, W. J., and S. Mulaik. 1940. The spiders of Texas. Bulletin of the American Museum of Natural History 77: 307–340. Vetter, R. S. 2008. Spiders of the genus Loxosceles (Araneae: Sicariidae): A review of biological, medical and psychological aspects regarding envenomations. Journal of Arachnology 36: 150–163.

2. Identification Gertsch, W. J., and F. Ennik. 1983. The spider genus Loxosceles in North America, Central America, and the West Indies (Araneae, Loxoscelidae). Bulletin of the American Museum of Natural History 175: 264–360. 167

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REFERENCES AND FURTHER READING Gertsch, W. J., and F. E. Russell. 1975. Loxosceles deserta Gertsch. Toxicon 13: 203–204. Greene, A., N. L. Breisch, T. Boardman, B. B. Pagac Jr., E. Kunickis, R. K. Howes, and P. V. Brown. 2009. The Mediterranean recluse spider, Loxosceles rufescens (Dufour): An abundant but cryptic inhabitant of deep infrastructure in the Washington, D.C. area (Arachnida: Araneae: Sicariidae). American Entomologist 55: 158–167. Vetter, R. S. 1999. Identifying and misidentifying the brown recluse spider. Dermatology Online 5 (2): http://escholarship.org/uc/item/6sj701ns. Vetter, R. S. 2011. Spiders. In: Handbook of pest control: The behavior, life history, and control of household pests, 10th ed., ed. S. Hedges, 1082–1117. Mallis Handbook Company.

3. Misidentification Vetter, R. S. 1998. Envenomation by an agelenid spider, Agelenopsis aperta, previously considered harmless. Annals of Emergency Medicine 32: 739–741. Vetter, R. S. 1999. Identifying and misidentifying the brown recluse spider. Dermatology Online 5 (2): http://escholarship.org/uc/item/6sj701ns. Vetter, R. S. 2005. Arachnids submitted as suspected brown recluse spiders (Araneae: Sicariidae): Loxosceles spiders are virtually restricted to their known distributions but are perceived to exist throughout the United States. Journal of Medical Entomology 42: 512–521. Vetter, R. S. 2008. Spiders of the genus Loxosceles (Araneae: Sicariidae): A review of biological, medical and psychological aspects regarding envenomations. Journal of Arachnology 36: 150–163. Vetter, R. S. 2009. Arachnids misidentified as brown recluse spiders by medical personnel and other authorities in North America. Toxicon 54: 545–547.

4. Life History and Biology de Andrade, R. M. G., K. C. de Oliveira, A. L. Giusti, W. E. da Silva, and D. V. Tambourgi. 1999. Ontogenetic development of Loxosceles intermedia spider venom. Toxicon 37: 627–632. Eberhard, W. G., G. Barrantes, and J.-L. Weng. 2006. The mystery of how spiders extract food without masticating prey. Bulletin of the British Arachnological Society 13: 372–376. Eskafi, F. M., J. L. Frazier, R. R. Hocking, and B. R. Norment. 1977. Influence of environmental factors on longevity of the brown recluse spider. Journal of Medical Entomology 14: 221–228. Fischer, M. L., and J. Vasconcellos-Neto. 2003. Determination of the maximum and minimum lethal temperatures (LT50) for Loxosceles intermedia MelloLeitão, 1934 and L. laeta (Nicolet, 1849) (Araneae, Sicariidae). Journal of Thermal Biology 28: 563–570.

REFERENCES AND FURTHER READING Fischer, M. L., and J. Vasconcellos-Neto. 2005. Parameters affecting fecundity of Loxosceles intermedia Mello-Leitão 1934 (Araneae, Sicariidae). Journal of Arachnology 33: 670–680. Fischer, M. L., and J. Vasconcellos-Neto. 2005. Microhabitats occupied by Loxosceles intermedia and Loxosceles laeta (Araneae: Sicariidae) in Curitiba, Paraná, Brazil. Journal of Medical Entomology 42: 756–765. Fischer, M. L., J. Vasconcellos-Neto, and L. G. dos Santos Neto. 2006. The prey and predators of Loxosceles intermedia Mello-Leitão 1934 (Araneae, Sicariidae). Journal of Arachnology 34: 485–488. Fischer, M. L., A. Cokl, E. N. Ramires, E. Marques-da-Silva, C. Delay, J. D. Fontana, L. Donatti, V. F Schneider, and F. de Assis Marques. 2009. Sound is involved in multimodal communication of Loxosceles intermedia Mello-Leitão, 1934 (Araneae: Sicariidae). Behavioural Processes 82: 236–243. Gorham, J. R., J. Ross, and A. W. Vasquez. 1969. The brown recluse spider (Loxosceles reclusa) in a natural habitat in Georgia. Sanscript 3 (1): 7–9. Hite, J. M. 1966. The biology of the brown recluse spider, Loxosceles reclusa Gertsch and Mulaik. Ph.D. dissertation. Kansas State University, Manhattan, Kansas. Hite, J. M., W. J. Gladney, J. L. Lancaster, and W. H. Whitcomb. 1966. Biology of the brown recluse spider. University of Arkansas Agricultural Experiment Station Bulletin no. 711. Horner, N. V., and K. W. Stewart. 1967. Life history of the brown spider, Loxosceles reclusa Gertsch and Mulaik. Texas Journal of Science 19: 334–347. Lowrie, D.C. 1980. Starvation longevity of Loxosceles laeta (Nicolet) (Araneae). Entomological News 91: 130–132. Parks, J., W. V. Stoecker, and C. Kristensen. 2006. Observations on Loxosceles reclusa (Araneae, Sicariidae) feeding on short-horned grasshoppers. Journal of Arachnology 34: 221–226. Richman, D. B. 1973. Field studies on the biology of Loxosceles arizonica Gertsch and Mulaik (Araneae, Sicariidae). Journal of the Arizona Academy of Sciences 8: 124–126. Rinaldi, I. M. P., L. C. Forti, and A. A. Stropa. 1997. On the development of the brown spider Loxosceles gaucho Gertsch (Araneae, Sicariidae): The nymphoimaginal period. Revista Brasileira de Zoologia 14: 697–706. Sandidge, J. 2003. Scavenging in brown recluse spiders. Nature 426: 30. Sandidge, J., and J. L. Hopwood. 2005. Brown recluse spiders: A review of biology, life history and pest management. Transactions of the Kansas Academy of Science 108: 99–108. Saupe, E. E., M. Papes, P. A. Selden, and R. S. Vetter. 2011. Tracking a medically important arachnid: Climate change, ecological niche modeling, and the brown recluse spider (Loxosceles reclusa). PLoS One 6: 17–31. Schenone, H., A. Rojas, H. Reyes, F. Villarroel, and G. Suarez. 1970. Prevalence of Loxosceles laeta in houses in central Chile. American Journal of Tropical Medicine and Hygiene 19: 564–567.

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REFERENCES AND FURTHER READING Vetter, R. S. 2008. Spiders of the genus Loxosceles (Araneae: Sicariidae): A review of biological, medical and psychological aspects regarding envenomations. Journal of Arachnology 36: 150–163. Vetter, R. S. 2011. Scavenging by spiders (Araneae) and its relationship to pest management of the brown recluse spider. Journal of Economic Entomology 104: 986–989. Vetter, R. S. 2011. Seasonality of brown recluse spiders, Loxosceles reclusa, submitted by the general public: Implications for physicians regarding loxoscelism diagnoses. Toxicon 58: 623–625. Vetter, R. S., and D. K. Barger. 2002. An infestation of 2,055 brown recluse spiders (Araneae: Sicariidae) and no envenomations in a Kansas home: Implications for bite diagnoses in non-endemic areas. Journal of Medical Entomology 39: 948–951. Vetter, R. S., and M. K. Rust. 2008. Refugia preferences by the spiders Loxosceles reclusa and Loxosceles laeta (Araneae: Sicariidae). Journal of Medical Entomology 45: 36–41. Vetter, R. S., and M. K. Rust. 2010. Periodicity of molting and resumption of postmolt feeding in the brown recluse spider, Loxosceles reclusa (Araneae: Sicariidae). Journal of the Kansas Entomological Society 83: 306–312.

5. Distribution Bradley, R. A. 2004. In Ohio’s backyard: Spiders. Columbus, OH: Ohio Biological Survey. Cramer, K. L., and A. V. Mayright. 2008. Cold temperature tolerance and the distribution of the brown recluse spider Loxosceles reclusa (Araneae, Sicariidae) in Illinois. Journal of Arachnology 36: 136–139. Cramer, K. L., and R. S. Vetter. 2014. Distribution of the brown recluse spider (Araneae: Sicariidae) in Illinois and Iowa. Journal of Medical Entomology 51: 46–49. Duncan, R. P., M. R. Rynerson, C. Ribera, and G. J. Binford. 2010. Diversity of Loxosceles spiders in Northwestern Africa and molecular support for cryptic species in the Loxosceles rufescens lineage. Molecular Phylogenetics and Evolution 55: 234–248. Fischer, M. L., J. Vasconcellos-Neto, and L. G. dos Santos Neto. 2006. The prey and predators of Loxosceles intermedia Mello-Leitão 1934 (Araneae, Sicariidae). Journal of Arachnology 34: 485–488. Frithsen, I. L., R. S. Vetter, and I. C. Stocks. 2007. Reports of envenomation by brown recluse spiders exceed verified specimens of Loxosceles spiders in South Carolina. Journal of the American Board of Family Medicine 20: 483–488. Gertsch, W. J. 1967. The spider genus Loxosceles in South America (Araneae, Scytodidae). Bulletin of the American Museum of Natural History 136: 117–174.

REFERENCES AND FURTHER READING Gertsch, W. J., and F. Ennik. 1983. The spider genus Loxosceles in North America, Central America, and the West Indies (Araneae, Loxoscelidae). Bulletin of the American Museum of Natural History 175: 264–360. Greene, A., N. L. Breisch, T. Boardman, B. B. Pagac Jr., E. Kunickis, R. K. Howes, and P. V. Brown. 2009. The Mediterranean recluse spider, Loxosceles rufescens (Dufour): An abundant but cryptic inhabitant of deep infrastructure in the Washington, D.C. area (Arachnida: Araneae: Sicariidae). American Entomologist 55: 158–167. Kaston, B. J. 1981. Spiders of Connecticut. State geological and natural history survey of Connecticut. Bulletin no. 70. Lotz, L. N. 2012. Present status of Sicariidae (Arachnida: Araneae) in the Afrotropical region. Zootaxa 3522: 1–41. Rapp, W. F. 1980. A catalog of spiders of Nebraska. Novitates Arthropodae 1 (2): 1–39. Saupe, E. E., M. Papes, P. A. Selden, and R. S. Vetter. 2011. Tracking a medically important arachnid: Climate change, ecological niche modeling, and the brown recluse spider (Loxosceles reclusa). PLoS One 6: 17–31. Schenone, H., A. Rojas, H. Reyes, F. Villarroel, and G. Suarez. 1970. Prevalence of Loxosceles laeta in houses in central Chile. American Journal of Tropical Medicine and Hygiene 19: 564–567. Stoaks, R. D. 1980. Occurrence of the brown recluse spider (Araneae: Loxoscelidae) in Iowa. Proceedings of the Iowa Academy of Science 87: 159. Taucare-Rios, A., A. D. Brescovit, and M. Canals. 2013. Synanthropic spiders (Arachnida: Araneae) from Chile. Revista Ibérica de Aracnología 23: 49–56. Vetter, R. S. 2005. Arachnids submitted as suspected brown recluse spiders (Araneae: Sicariidae): Loxosceles spiders are virtually restricted to their known distributions but are perceived to exist throughout the United States. Journal of Medical Entomology 42: 512–521. Vetter, R. S. 2008. Spiders of the genus Loxosceles (Araneae: Sicariidae): A review of biological, medical and psychological aspects regarding envenomations. Journal of Arachnology 36: 150–163. Vetter, R. S. 2009. The distribution of the brown recluse spider in the southeastern quadrant of the United States in relation to loxoscelism diagnoses. Southern Medical Journal 102: 518–522. Vetter, R. S. 2011. Spiders. In: Handbook of pest control: The behavior, life history, and control of household pests, 10th ed., ed. S. Hedges, 1082–1117. Mallis Handbook Company. Vetter, R. S., P. E. Cushing, R. L. Crawford, and L. A. Royce. 2003. Diagnoses of brown recluse spider bites (loxoscelism) greatly outnumber actual verifications of the spider in four western American states. Toxicon 42: 413–418. Vetter, R. S., G. B. Edwards, and L. F. James. 2004. Reports of envenomation by brown recluse spiders (Araneae: Sicariidae) outnumber verifications of Loxosceles spiders in Florida. Journal of Medical Entomology 41: 593–597.

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REFERENCES AND FURTHER READING Vetter, R. S., N. C. Hinkle, and L. M. Ames. 2009. Distribution of the brown recluse spider (Araneae: Sicariidae) in Georgia with a comparison of poison center reports of envenomations. Journal of Medical Entomology 46: 15–20. Waldron. W. G. 1969. Loxosceles laeta (Nicolet), an introduced species in Los Angeles County. Bulletin of the Entomological Society of America 15: 377–379. Zimmerman, S. P., J. A. Rothman, J. L. Hansen, M. M Rusin, M. A. Bertone, and H. J. Hamrick. 2014. Systemic loxoscelism in a nonendemic area: A diagnostic challenge for the unsuspecting physician. Clinical Pediatrics 53: 1098–1100.

6. Medical Aspects Anderson, P. C. 1990. Loxoscelism and the history of the Missouri brown spider: A recollection of Dr. Joseph Flynn. Missouri Medicine 87: 747–752. Anderson, P. C. 1991. Loxoscelism threatening pregnancy: Five cases. American Journal of Obstetrics and Gynecology 165: 1454–1456. Anderson, P. C. 1998. Missouri brown recluse spider: A review and update. Missouri Medicine 95: 318–322. Atkins, J. A., C. W. Wingo, and W. A. Sodeman. 1957. Probable cause of necrotic spider bite in the Midwest. Science 126: 73. Cacy, J., and J. W. Mold. 1999. The clinical characteristics of brown recluse spider bites treated by family physicians: An OKPRN study. Journal of Family Practice 48: 536–542. Caveness, W. A. 1872. Insect bite, complicated with fever. Nashville Journal of Medicine and Surgery 10: 333–337. Elston, D. M., S. D. Miller, R. J. Young III, J. Eggers, D. McGlasson, W. H. Schmidt, and A. Bush. 2005. Comparison of colchicine, dapsone, triamcinolone, and diphenhydramine therapy for the treatment of brown recluse spider envenomation: A double-blind, controlled study in a rabbit model. Archives of Dermatology 141: 595–597. Gomez, H. F., D. M. Krywko, and W. V. Stoecker. 2002. A new assay for the detection of Loxosceles species (brown recluse) spider venom. Annals of Emergency Medicine 39: 469–474. Gotten, H. B., and J. J. MacGowan. 1940. Blackwater fever (hemoglobinuria) caused by spider bite. Journal of the American Medical Association 114: 1547. Isbister, G. K., and H.-W. Fan. 2011. Spider bites. Lancet 378: 2039–2047. Malaque, C. M. S., M. L. Santoro, J. L C. Cardoso, M. R. Conde, C. T. G. Novaes, J. Y. Risk, F. O. S. França, C. R. de Medeiros, and H.-W. Fan. 2011. Clinical picture and laboratorial evaluation in human loxoscelism. Toxicon 58: 664–671. Masters, E. J. 1998. Loxoscelism. New England Journal of Medicine 339: 379. Masters, E. J., and L. E. King Jr. 1994. Differentiating loxoscelism from Lyme disease. Emergency Medicine 26 (10): 47–49. Mullen, G. R., and R. S. Vetter. 2009. Spiders (Araneae). In: Medical and veterinary entomology, ed. G. R. Mullen and L. A. Durden, 403–424. Burlington, MA: Elsevier Press.

REFERENCES AND FURTHER READING Pace, L. B., and R. S. Vetter. 2009. Brown recluse spider envenomation: A clinical review for veterinarians. Journal of Veterinary Emergency and Critical Care 19: 329–336. Patel, K. D., V. Modur, G. A. Zimmerman, S. M. Prescott, and T. M. McIntyre. 1994. The necrotic venom of the brown recluse spider induces dysregulated endothelial cell-dependent neutrophil activation. Journal of Clinical Investigation 94: 631–642. Pauli, I., J. Puka, I. C. Gubert, and J. C. Minozzo. 2006. The efficacy of antivenom in loxoscelism treatment. Toxicon 48: 123–137. Payne, K. S., K. Schilli, K. Meier, R. K. Rader, J. A. Dyer, J. W. Mold, J. A. Green, and W. V. Stoecker. 2014. Extreme pain from brown recluse spider bites: Model for cytokine-driven pain. Journal of the American Medical Association, Dermatology. doi:10.1001/jamadermatol.2014.605. Presley, T. E. 1896. A case of spider bite. Memphis Medical Monthly 16: 520–522. Rader, R. K., W. V. Stoecker, J. M. Malters, M. T. Marr, and J. A. Dyer. 2012. Seasonality of brown recluse populations is reflected by numbers of brown recluse envenomations. Toxicon 60: 1–3. Rees, R., D. Campbell, E. Rieger, and L. E. King. 1987. The diagnosis and treatment of brown recluse spider bites. Annals of Emergency Medicine 16: 945–949. Rosen, J. L., J. K. Dumitru, E. W. Langley, and C. A. Meade Olivier. 2012. Emergency department death from systemic loxoscelism. Annals of Emergency Medicine 60: 439–441. Russell, F. E., W. G. Waldron, and M. B. Madon. 1969. Bites by the brown spiders Loxosceles unicolor and Loxosceles arizonica in California and Arizona. Toxicon 7: 109–112. Sams, H. H., S. B. Hearth, L. L. Long, D. C. Wilson, D. H. Sanders, and L. E. King Jr. 2001. Nineteen documented cases of Loxosceles reclusa envenomation. Journal of the American Academy of Dermatology 44: 603–608. Schmaus, L. F. 1929. Case of arachnoidism (spider bite). Journal of the American Medical Association 92: 1265–1266. Swanson, D. L., and R. S. Vetter. 2005. Bites of brown recluse spiders and suspected necrotic arachnidism. New England Journal of Medicine 352: 700–707. Swanson, D. L., and R. S. Vetter. 2006. Loxoscelism. Clinical Dermatology 24: 213–221. Vetter, R. S. 2008. Spiders of the genus Loxosceles (Araneae: Sicariidae): A review of biological, medical and psychological aspects regarding envenomations. Journal of Arachnology 36: 150–163. Vetter, R. S. 2011. Seasonality of brown recluse spiders, Loxosceles reclusa, submitted by the general public: Implications for physicians regarding loxoscelism diagnoses. Toxicon 58: 623–625. Vetter, R. S. 2013. Spider envenomation in North America. Critical Care Nursing Clinics of North America 25: 205–223. Vetter, R. S., and D. K. Barger. 2002. An infestation of 2,055 brown recluse spiders (Araneae: Sicariidae) and no envenomations in a Kansas home: Implications for bite diagnoses in non-endemic areas. Journal of Medical Entomology 39: 948–951.

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REFERENCES AND FURTHER READING Vetter, R. S., and G. K. Isbister. 2008. Medical aspects of spider bites. Annual Review of Entomology 53: 409–429. Vetter, R. S., P. E. Cushing, R. L. Crawford, and L. A. Royce. 2003. Diagnoses of brown recluse spider bites (loxoscelism) greatly outnumber actual verifications of the spider in four western American states. Toxicon 42: 413–418. Vetter, R. S., D. L. Swanson, S. A. Weinstein, and J. White. 2015. Do spiders vector bacteria during bites? The evidence indicates otherwise. Toxicon 93: 171–174. Wasserman, G. S., and P. C. Anderson. 1983–84. Loxoscelism and necrotic arachnidism. Journal of Toxicology—Clinical Toxicology 21: 451–472. Wasserman, G. S., R. Garola, J. Marshall, and S. Gustafson. 1999. Death of a 7 year old by presumptive brown recluse spider bite. Journal of Toxicology—Clinical Toxicology 37: 614–615. Wilson, J. T. 1893. Poisoning by the bite of the southern spider. Transactions of the Southern Surgical and Gynecological Association 5: 406–411. Wright, S. W., K. D. Wrenn, L. Murray, and D. Seger. 1997. Clinical presentation and outcome of brown recluse spider bite. Annals of Emergency Medicine 30: 28–32. Zimmerman, S. P., J. A. Rothman, J. L. Hansen, M. M Rusin, M. A. Bertone, and H. J. Hamrick. 2014. Systemic loxoscelism in a nonendemic area: A diagnostic challenge for the unsuspecting physician. Clinical Pediatrics 53: 1098–1100.

7. Medical Misdiagnoses Baxtrom, C., T. Mongkolpradit, J. N. Kasimos, L. M. Braune, R. D. Wise, P. Sierwald, and K. R. Ramsey. 2006. Common house spiders are not likely vectors of community-acquired methicillin-resistant Staphylococcus aureus infections. Journal of Medical Entomology 43: 962–965. Bennett, R. G., and R. S. Vetter. 2004. Erroneous attribution of dermonecrotic lesions to brown recluse or hobo spiders in Canada. Canadian Family Physician 50: 1098–1101. Dominguez, T. J. 2004. It’s not a spider bite, it’s methicillin-resistant Staphylococcus aureus. Journal of the American Board of Family Practice 17: 220–226. Frithsen, I. L., R. S. Vetter, and I. C. Stocks. 2007. Reports of envenomation by brown recluse spiders exceed verified specimens of Loxosceles spiders in South Carolina. Journal of the American Board of Family Medicine 20: 483–488. Groopman, J. 2007. How doctors think. Boston: Houghton Mifflin. Isbister, G. K. 2004. Necrotic arachnidism: The myth of a modern plague. Lancet 364: 549–553. Masters, E. J., and L. E. King Jr. 1994. Differentiating loxoscelism from Lyme disease. Emergency Medicine 26 (10): 47–49. Montgomery, K. 2006. How doctors think: Clinical judgment and the practice of medicine. New York: Oxford University Press. Moran, G. J., A. Krishnadasan, R. J. Gorwitz, G. E. Fosheim, L. K. McDougal, R. B. Carey, and D. A. Talan. 2006. Methicillin-resistant S. aureus infections among patients in emergency rooms. New England Journal of Medicine 355: 666–674.

REFERENCES AND FURTHER READING Osterhoudt, K. C., T. Zaoutis, and J. J. Zorc. 2002. Lyme disease masquerading as brown recluse spider bite. Annals of Emergency Medicine 39: 558–561. Rader, R. K., W. V. Stoecker, J. M. Malters, M. T. Marr, and J. A. Dyer. 2012. Seasonality of brown recluse populations is reflected by numbers of brown recluse envenomations. Toxicon 60: 1–3. Roche, K. J., M. W. Chang, and H. Lazarus. 2001. Cutaneous anthrax infection. New England Journal of Medicine 345: 1611. Russell, F. E. 1986. A confusion of spiders. Emergency Medicine 18 (11): 8–13. Russell, F. E., and W. J. Gertsch. 1983. Letter to the editor. Toxicon 21: 337–339. Suchard, J. R. 2011. “Spider bite” lesions are usually diagnosed as skin and soft-tissue infections. Journal of Emergency Medicine 41: 473–481. Swanson, D. L., and R. S. Vetter. 2005. Bites of brown recluse spiders and suspected necrotic arachnidism. New England Journal of Medicine 352: 700–707. Vetter, R. S. 2008. Spiders of the genus Loxosceles (Araneae: Sicariidae): A review of biological, medical and psychological aspects regarding envenomations. Journal of Arachnology 36: 150–163. Vetter, R. S. 2009. The distribution of the brown recluse spider in the southeastern quadrant of the United States in relation to loxoscelism diagnoses. Southern Medical Journal 102: 518–522. Vetter, R. S. 2011. Seasonality of brown recluse spiders, Loxosceles reclusa, submitted by the general public: Implications for physicians regarding loxoscelism diagnoses. Toxicon 58: 623–625. Vetter, R. S., and S. P. Bush. 2002. Chemical burn misdiagnosed as brown recluse spider bite. American Journal of Emergency Medicine 20: 68–69. Vetter, R. S., and S. P. Bush. 2002. The diagnosis of brown recluse spider bite is overused for dermonecrotic wounds of uncertain etiology. Annals of Emergency Medicine 39: 544–546. Vetter, R. S., and S. P. Bush. 2002. Reports of presumptive brown recluse spider bites reinforce improbable diagnosis in regions of North America where the spider is not endemic. Clinical Infectious Diseases 35: 442–445. Vetter, R. S., and R. B. Furbee. 2006. Caveats in interpreting poison control centre data for spider bites in epidemiology studies. Public Health 120: 179–181. Vetter, R. S., and G. K. Isbister. 2008. Medical aspects of spider bites. Annual Review of Entomology 53: 409–429. Vetter, R. S., and D. L. Swanson. 2007. Of spiders and zebras: Publication of inadequately documented loxoscelism case reports. Journal of the American Academy of Dermatology 56: 1063–1064. Vetter, R. S., P. E. Cushing, R. L. Crawford, and L. A. Royce. 2003. Diagnoses of brown recluse spider bites (loxoscelism) greatly outnumber actual verifications of the spider in four western American states. Toxicon 42: 413–418. Vetter, R. S., G. B. Edwards, and L. F. James. 2004. Reports of envenomation by brown recluse spiders (Araneae: Sicariidae) outnumber verifications of Loxosceles spiders in Florida. Journal of Medical Entomology 41: 593–597. Vetter, R. S., B. B. Pagac, R. W. Reiland, D. T. Bolesh, and D. L. Swanson. 2006. Skin

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REFERENCES AND FURTHER READING lesions in barracks: Consider community-acquired methicillin-resistant Staphylococcus aureus infection instead of spider bites. Military Medicine 171: 830–832.

8. Human Psychology and the Brown Recluse Spider Benoit, R., and J. R. Suchard. 2006. Necrotic skin lesions: Spider bite—or something else? Consultant 46: 1386–1394. Crawford, R. Spider myths website. http://www.washington.edu/burkemuseum/ spidermyth/index.html. DiFonzo, N., and P. Bordia. 2007. Rumor psychology: Social and organizational approaches. Washington, DC: American Psychological Association. Gladwell, M. 2002. The tipping point: How little things can make a big difference. New York: Back Bay Books. Isbister, G. K. 2004. Necrotic arachnidism: The myth of a modern plague. Lancet 364: 549–553. Lockwood, J. A. 2013. The infested mind: Why we fear, loathe, and love insects. Oxford: Oxford University Press. Nesse, R. M. 2001. The smoke detector principle: Natural selection and the regulation of defensive response. Annals of the New York Academy of Sciences 935: 75–85. Nickerson, R. S. 1998. Confirmation bias: A ubiquitous phenomenon in many guises. Review of General Psychology 2: 175–220. Shermer, M. 2002. Why people believe weird things. New York: Henry Holt. SNOPES. Thumb injury caused by a brown recluse spider? http://www.snopes. com/photos/bugs/brownrecluse.asp. Vetter, R. S. 2004. Myths about spider envenomations and necrotic skin lesions. Lancet 364: 484–485. Vetter, R. S. 2008. Spiders of the genus Loxosceles (Araneae: Sicariidae): A review of biological, medical and psychological aspects regarding envenomations. Journal of Arachnology 36: 150–163. Vetter, R. S. 2010. Myths based in science and medicine—how they initiate, propagate, and the role of peer-review research in dispelling them. Perspectives in Agriculture, Veterinary Science, Nutrition and Natural Resources 5, no. 041. Vetter, R. S. 2013. Arachnophobic entomologists: When two more legs makes a big difference. American Entomologist 59: 168–175. White, J. 2003. Debunking spider myths. Medical Journal of Australia 179: 180– 181.

9. Bites and Alleged Bites by Other Spiders Binford, G. J. 2001. An analysis of geographic and intersexual chemical variation in venoms of the spider Tegenaria agrestis (Agelenidae). Toxicon 39: 955–968. Isbister, G. K., and M. R. Gray. 2003. White-tail spider bite: A prospective study of 130 definite bites by Lampona species. Medical Journal of Australia 179: 199–202.

REFERENCES AND FURTHER READING McKeown, N., R. S. Vetter, and R. G. Hendricksen. 2014. Verified spider bites in Oregon (USA) with the intent to assess hobo spider venom toxicity. Toxicon 84: 51–55. Mullen, G. R., and R. S. Vetter. 2009. Spiders (Araneae). In: Medical and veterinary entomology, ed. G. R. Mullen and L. A. Durden, 403–424. Burlington, MA: Elsevier Press. Ribeiro, L. A., M. T. Jorge, R. V. Piesco, and S. A. Nishioka. 1990. Wolf spider bites in São Paulo, Brazil: A clinical and epidemiological study of 515 cases. Toxicon 28: 715–717. Vetter, R. S. 1998. Envenomation by an agelenid spider, Agelenopsis aperta, previously considered harmless. Annals of Emergency Medicine 32: 739–741. Vetter, R. S. 2011. Spiders. In: Handbook of pest control: The behavior, life history, and control of household pests, 10th ed., ed. S. Hedges, 1082–1117. Mallis Handbook Company. Vetter, R. S. 2012. Envenomation by spiders of the genus Hololena (Araneae: Agelenidae). Toxicon 60: 312–314. Vetter, R. S. 2013. Spider envenomation in North America. Critical Care Nursing Clinics of North America 25: 205–223. Vetter, R. S., and G. K. Isbister. 2004. Do hobo spider bites cause dermonecrotic injuries? Annals of Emergency Medicine 44: 605–607. Vetter, R. S., and G. K. Isbister. 2006. Verified bites by the woodlouse spider, Dysdera crocata. Toxicon 47: 826–829. Vetter, R. S., and G. K. Isbister. 2008. Medical aspects of spider bites. Annual Review of Entomology 53: 409–429. Vetter, R. S., G. K. Isbister, S. P. Bush, and L. J. Boutin. 2006. Verified bites by Cheiracanthium spiders in the United States and Australia: Where is the necrosis? American Journal of Tropical Medicine and Hygiene 74: 1043–1048. Vetter, R. S., A. H. Roe, R. G. Bennett, C. R. Baird, L. A. Royce, W. T. Lanier, A. L. Antonelli, and P. E. Cushing. 2003. Distribution of the medically-implicated hobo spider (Araneae: Agelenidae) and its harmless congener, Tegenaria duellica in the United States and Canada. Journal of Medical Entomology 40: 159–164. White, J. 2003. Debunking spider myths. Medical Journal of Australia 179: 180–181.

10. Control Measures Hedges, S. A., and R. S. Vetter. 2012. PCT field guide for the management of urban spiders. Cleveland, OH: GIE Media. Holper, J. 2007. What brown can do for you. Pest Control Technology 35 (4): 87–90. Ramires, E. N., A. V. L. Retzlaff, L. R. Deconto, J. D. Fontana, F. A. Marques, and E. Marques-da-Silva. 2007. Evaluation of the efficacy of vacuum cleaners for the integrated control of brown spider Loxosceles intermedia. Journal of Venom and Animal Toxins 13: 607–619.

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REFERENCES AND FURTHER READING Sandidge, J. S. 2009. Brown recluse spiders: A knowledge based guide to control and elimination. Privately printed. Sandidge, J., and J. L. Hopwood. 2005. Brown recluse spiders: A review of biology, life history and pest management. Transactions of the Kansas Academy of Science 108: 99–108. Stropa, A. A. 2010. Effect of architectural angularity on refugia selection by the brown spider, Loxosceles gaucho. Medical and Veterinary Entomology 24: 273–277. Vetter, R. S. 2011. Scavenging by spiders (Araneae) and its relationship to pest management of the brown recluse spider. Journal of Economic Entomology 104: 986–989. Vetter, R. S. 2011. Spiders. In: Handbook of pest control: The behavior, life history, and control of household pests, 10th ed., ed. S. Hedges, 1082–1117. Mallis Handbook Company. Vetter, R. S., and M. K. Rust. 2008. Refugia preferences by the spiders Loxosceles reclusa and Loxosceles laeta (Araneae: Sicariidae). Journal of Medical Entomology 45: 36–41. Vetter, R. S., and M. K. Rust. 2010. Influence of spider silk on the refugia preferences of the recluse spiders Loxosceles reclusa and Loxosceles laeta (Araneae: Sicariidae). Journal of Economic Entomology 103: 808–815. Vetter, R. S., M. S. Hoddle, D.-H. Choe, and E. Thoms. 2014. Exposure of brown recluse and brown widow spiders (Araneae: Sicariidae, Theridiidae) to a commercial sulfuryl fluoride fumigation. Journal of Economic Entomology 107: 1813–1817.

INDEX

Note: Page numbers in italics refer to illustrations. abdomen , 12, 15, 24 cardiac mark, 16, 29 coloration , 15–16, 16 Acari, 5 accidents, automobile, 93, 93, 129, 134 Africa, 23, 88, 140, 144 Agelenidae. See spider, funnel weaver Agelenopsis. See spider, funnel weaver Alabama, distribution , 78 Alaska, distribution , 80 amputation , 101 anatomy, 11–19, 13 abdominal hairs, 15 autotomy, 57 cardiac mark, 16, 29 cephalothorax, 12, 13, 14 cephalothorax widths, 50, 51 chelicerae, 5, 19 cribellate, 58 cribellum, 58 embolus, 17, 18, 18 exoskeleton , 52, 56, 57 eye pattern , 12, 12, 13, 17, 19, 22–23, 24, 85 fang, 19, 19 leg autotomy, 57 leg coloration , 23, 23 leg hairs/spines, 23, 24 leg regeneration , 57 pedicel, 54 procurved, 12

recurved, 12 reproductive structures, 16–18, 17, 18 uncate, 19, 19 violin pattern , 11, 12, 13, 14–15, 22, 23, 24, 85, 86 Anderson , Phillip, 103, 106, 108–109 anthrax. See infection , bacterial antivenom, 104 apache recluse. See Loxosceles apachea Aphonopelma. See spider, tarantula appearance of credibility, 131 Arachnida, 5 arachnophobia, 125–127 arana de detras de los cuadros, 61 arana de los rincones, 61 Araneae, 5–6 Araneidae. See spider, orb weaver Araneomorphae, 5–6, 58 Arizona recluse. See Loxosceles arizonica Arkansas, 75 Asia, 89 Australia, 89 autotomy, 57 bacteria. See infection , bacterial Bactrim, 119 badge of suffering, 129–130 Baja recluse. See Loxosceles palma ballooning. See dispersal, ballooning belief bias, 127 Big Bend recluse. See Loxosceles blanda

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180

INDEX binomial name, 6 bite, non-recluse. See spider bites bite, recluse. See loxoscelism black widow spider. See spider, black widow blood thinners, 122 burns, 121 California Loxosceles deserta, 82–83 Loxosceles laeta, 64, 87 overdiagnosis of bites, 114 Canada distribution , 10, 80 overdiagnosis of bites, 80–81, 114 cancer, 2, 121–122 captivity feeding, 68–69 rearing, 67–69 cardiac mark. See anatomy, cardiac mark Caribbean , 88 Central America, 87–88 cephalothorax widths, 50, 51 Charlotte’s Web, 33, 63 Cheiracanthium. See spider, yellow sac chemical communication , 43 Chilean recluse. See Loxosceles laeta classification Araneae, 5–6 Araneomorphae, 5–6 binomial name, 6 cribellate, 58 ecribellate, 58 entelegyne, 6 haplogyne, 6, 17, 63 Liphistiomorphae, 6 Mygalomorphae, 6 naming scheme, 5 scientific naming, 5–10 specific epithet, 6 Clindamycin , 119 collecting, 66–67 Colorado, overdiagnosis of bites, 114 confirmational bias, 128 Connecticut, distribution , 81 cribellate, 58 cribellum, 58 cytokines, 101–102 Dapsone, 102–104 dates. See year of significance

death. See loxoscelism, death debridement, 103 dermonecrosis, 1, 94, 98–104, 98 progression of, 98, 99–101 treatment, 103–104 desert recluse. See Loxosceles deserta development. See growth diabetes, 102 diabetic ulcer, 122 dialysis, 106 dispersal ballooning, 63 non-recluse spiders, 63 recluse spiders, 63 distribution map, 75 Dolomedes. See spider, fishing drugs Bactrim, 119 Clindamycin , 119 Dapsone, 102–104 Dysdera. See spider, woodlouse ecribellate, 58 egg sac, 45 black widow, 46 construction , 44–45 development within , 47–50, 48, 50 guarding behavior, 45, 49 Loxosceles gaucho, 46–48 Loxosceles intermedia, 46 quantity, 45–46 seasonality, 47, 47 tarantula, 46 viability, 46 ELISA bioassay, 102 entelegyne, 6, 17 entertainment value, 128 epidemiology of bites, 94–95 Eratigena, See spider, funnel weaver exoskeleton , 52, 56, 57 eye pattern , 12, 12, 13, 17, 19, 22–23, 24, 85 fang spider, cellar, 19 spider, crevice weaver, 19 uncate, 19, 19 fear of rare event, 129 feeding in captivity, 68–69 Filistatidae. See spider, crevice weaver

INDEX Florida distribution , 81 overdiagnosis of bites, 114 poison control centers, 82 G6PD, 104 gangrenous spot, 96 Gasteracantha. See spider, orb weaver Georgia distribution , 78 in oak tree, 63–64 Gertsch, Willis, 9 global warming, 64 glucose-6-phosphate dehydrogenase, 104 Gnaphosidae. See spider, ground Grand Canyon recluse. See Loxosceles kaiba green lynx spider. See spider, green lynx growth cephalothorax width, 50, 51 egg development, 47–50, 48, 50 flexibility of instars, 50–52, 51 inside egg sac, 47–50, 48, 50 outside egg sac, 50–52 time to maturation , 40 habitat, 61–62, 154–155 surface preference, 154 haplogyne, 6, 17 non-ballooning behavior, 63 herpes. See infection , viral Herpyllus. See spider, ground Heteropoda. See spider, huntsman Hite, Maxine, 39, 43, 47, 49 hobo spider. See spider, hobo Holocnemus. See spider, cellar Hololena. See spider, funnel weaver Horner, Norman , 39, 43, 44, 47 hyperbaric oxygen , 104 Illinois, distribution , 76 Indiana, distribution , 76 infection , bacterial, 107–108, 115, 117–120 absence in bites, 107–108 anthrax, 120 Lyme disease, 2, 74, 100, 119–120 methicillin-resistant Staphylococcus aureus, 117–119

MRSA, 117–119 Streptococcus, 2, 101, 120 infection , fungal sporotrichosis, 120–121 infection , viral herpes (shingles), 121 influenza, 129 Iowa, distribution , 76 Kansas, distribution , 63, 79 Lenexa home, 62, 65, 157 Kentucky, distribution , 76–77 Kukulcania. See spider, crevice weaver latrodectism, 139–142 Latrodectus. See spider, black widow leg autotomy, 57 leg regeneration , 57 lifespan , 40 Liphistiomorphae, 6 Louisiana, distribution , 78 Loxosceles common names for genus, 7 pronunciation of name, 6 scientific meaning, 6 Loxosceles apachea, 7, 10, 78, 83 Loxosceles arizonica, 10, 83 envenomation , 110 habitat, 62 seasonality, 65 Loxosceles blanda, 7, 10, 14, 15, 78, 83 Canada, 80 Loxosceles boneti, 88 Loxosceles citigrada, 8 Loxosceles deserta, 7, 10, 14, 14, 82–83 envenomation , 110 habitat, 62–63 reproductive organs, 18, 18 seasonality, 66 Loxosceles devia, 10, 78, 83 Loxosceles gaucho egg sac, 46–47 feeding initiation , 50 South America, 88 time to maturation , 50 Loxosceles intermedia egg development, 46, 49 egg sac, 46, 46 egg viability, 46 mating behavior, 43

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INDEX Loxosceles intermedia (continued) South America, 88 temperature limits, 66 venom development, 57 Loxosceles kaiba, 10, 84 Loxosceles laeta, 7, 10, 86–87, 86 California, 64, 87, 110–111 Canada, 80 envenomation , 110–111 Florida, 81 growth, 40 Harvard Museum, 60, 87 maturation time, 40 populations in homes, 62 prey, 60 pronunciation of “laeta,” 24 size, 24 South America, 88 Loxosceles martha, 10, 83 Loxosceles palma, 10, 84 Loxosceles parramae, 88 Loxosceles reclusus original species name, 9 Loxosceles rufescens, 8–10, 84–86, 85 Africa, 88 Asia, 89 Australia, 89 Caribbean , 88 envenomation , 111 Europe, 88 Florida, 81 India, 89 reproductive organs, 18, 18 as Scytodes rufescens, 8 Washington D.C., 85–86 Loxosceles rufipes, 88 Loxosceles russelli, 10, 83 Loxosceles sabina, 10, 84 Loxosceles simillima, 88, 89 Loxosceles speluncarum, 88 Loxoscelidae, 10 loxoscelism, avoidance of bites, 160–162 categories of bite probabilities, 96, 106–107 categories of effects, 94, 97–99 death, 96, 99, 102 dermonecrosis, 1, 98–104 dermonecrotic progression , 99–101 dermonecrotic treatment, 103–104

differential diagnoses, 115–117 epidemiology, 94–95 fatality, 96, 99, 102 history of, 95–96 mechanism of dermonecrotic damage, 101–102 pets, 109–110 pregnancy, 109 remedies, 103–104 seasonality, 94 signs and symptoms, 99, 108 systemic, 99 systemic progression , 105–106 systemic treatment, 106 treatment, 103–104, 106 verified bites, 96–97, 97, 98, 98 Lycosidae. See spider, wolf lymphoma, 2 lymphomatoid papulosis, 122 lynx spider. See spider, green lynx map, distribution , 75 Martha recluse. See Loxosceles martha Masters, Edwin , 119 mating behavior, 17, 40–44, 41, 42 in captivity, 44 chemical communication , 43 reproductive organs, 16–18, 18 seasonality, 43–44 media sensationalism, 132–137, 133, 134, 136 medications Bactrim, 119 Clindamycin , 119 Dapsone, 102–104 Mediterranean recluse. See Loxosceles rufescens Metepeira, 63 methemoglobin , 104 methemoglobinemia, 104 methicillin-resistant Staphylococcus aureus. See infection , bacterial Micrathena. See spider, orbweaver Mimetidae. See spider, pirate Mimetus. See spider, pirate misdiagnoses of alleged bites, 80–82, 113–117 anthrax, 120 blood thinners, 122 burns, 121

INDEX cancer, 2, 121–122 diabetic ulcer, 122 herpes, 121 Lyme disease, 2, 74, 119–120 lymphoma, 2 lymphomatoid papulosis, 122 MRSA, 117–119 plant toxins, 121 poison ivy/oak, 121 pyoderma gangrenosum, 123 shingles, 121 sporotrichosis, 120–121 Staphylococcus, 117–119 Streptococcus, 2, 101, 120 Mississippi, distribution , 78 Missouri, 75 molting, 52–57, 53, 55, 56 asterisk pattern , 56, 57 exoskeleton , 52, 56, 57 inside egg sac, 47–49 variable number of molts, 50–52, 51 MRSA. See infection , bacterial museum Amer. Mus. of Nat. Hist. (NY), 73 Burke (WA), 82 Field (IL), 87 Harvard (Mus. of Comparative Zool., MA), 60, 87 Los Angeles Nat. Hist. Mus. (CA), 87 procedures, 71–74 Royal Ontario Mus. (Canada), 80 Mygalomorphae, 6 myths, 135–137 native distribution , 74–79 Nebraska, distribution , 76 necrosis. See loxoscelism, dermonecrosis necrotic arachnidism. See loxoscelism, dermonecrosis New Mexico, distribution , 78 North Carolina, distribution , 77 Oecobiidae. See spider, flatmesh weaver Ohio, distribution , 76 Oklahoma, distribution , 79 Olios. See spider, huntsman Opiliones, 5, 28 Oregon , overdiagnosis of bites, 81, 114 overdiagnosis of bites, 80–82, 113–117 Oxyopidae. See spider, green lynx

Parasteatoda. See spider, combfooted parson spider. See spider, ground pest control, 153–160 sticky traps, 155–158, 156, 157 vacuum cleaner, 158 pesticide treatment, 158–160 pets. See loxoscelism, pets Peucetia. See spider, green lynx phenology, 64–66 Pholcidae. See spider, cellar Pholcus. See spider, cellar Pisaurina. See spider, nursery web plant toxins, 121 poikilotherm, 39 poison control center, Florida, 82 poison ivy, 121 poison oak, 121 population size, 62–63 prey, 58–61 flies, 59 grasshoppers, 59 hunting strategies, 58–60 scavenging behavior, 59–60 procurved, 12 Psilochorus. See spider, cellar pus formation (lack of), 107–108 pyoderma gangrenosum, 123 pyramid automobile accidents, 93, 93 loxoscelism, 93–94, 94 rain cloud analogy, 75 rearing in captivity, 67–69 reclusus, as original species name, 9 recurved, 12 regeneration of legs, 57 reproductive structures, 16–18 embolus, 17, 18, 18 female, 18, 18 male palp, 17, 18, 18 RICE therapy, 103 Russell, Findlay, 113 Salticidae. See spider, jumping scavenging behavior, 59–60 scientific naming. See classification Scorpiones, 5 Scytodes. See spider, spitting Scytodes rufescens, 8 Scytodidae, 9–10, 27–28

183

184

INDEX seasonality activity period, 64–66, 65 bites, 94 egg sacs, 47 mating behavior, 43–44 shifting blame, 130 shingles. See infection , viral Sicariidae, 5, 9, 10 Sicarius, 9, 10 silk, 25, 25, 58 silverfish, 60 Simon , Eugène, 8–9 site fidelity, 58 size, 24, 51 smoke detector principle, 128–129 South Africa, 23, 140, 144 South America, 86, 88, 104, 142 South Carolina distribution , 77–78 overdiagnosis of bites, 114 Sparassidae. See spider, huntsman specific epithet, 6 sphingomyelinase D. See venom, sphingomyelinase D spider black widow, 1, 11, 33–34, 46, 139 cellar, 22, 28–29, 28 comb-footed, 33–34, 34 crevice weaver, 22, 26–27, 26 false black widow, 33, 34 fishing, 37 flatmesh weaver, 22 funnel weaver, 23, 30–32, 31, 145 green lynx, 150, 150 ground, 38, 38 hobo, 31, 145 huntsman , 22, 36–37, 57 jumping, 11, 149 nursery web, 37 orb weaver, 11, 32–33, 32 pirate, 22, 24 sac, 37, 38 spitting, 16, 27–28, 27 Sydney funnel web, 30, 110, 148 tarantula, 6, 46, 143 tengellid, 22, 35–36, 36 wolf, 19, 19, 29, 30 woodlouse, 34–35, 35 yellow sac, 37, 38

spider bites avoidance of, 160–162 black widow, 140–142 false black widow, 148 funnel weaver, 148 green lynx, 150, 150 hobo, 145–147, 145 jumping, 149, 149 orb weaver, 149–150 parson , 151 tarantula (assumed), 95 wolf, 142–143 woodlouse, 151 yellow sac, 143–144 sporotrichosis. See infection , fungal Stegodyphus, 63 stickiness factor, 130–131 sticky traps, 155–158, 156, 157 Streptococcus. See infection , bacterial stridulation , 40, 43 Sydney funnel web spider. See spider, Sydney funnel web synanthropic, 62 tarantella, 143 tarantism, 143 tarantula. See spider, tarantula Tegenaria. See spider, funnel weaver temperature effect on development, 49–50, 50 survival limits, 66 Tengellidae. See spider, tengellid Tennessee, distribution , 77 Texas, distribution , 78 Texas recluse. See Loxosceles devia Theridiidae. See spider, combfooted thumb injury, 136–137, 136 Titiotus. See spider, tengellid Trachelas. See spider, sac Trachelidae. See spider, sac traps, sticky, 155–158, 156, 157 treatment, insecticidal, 158–160 treatment, medical, 103–104, 106 antivenom, 104 Dapsone, 104 debridement, 103 dialysis, 106 hyperbaric oxygen , 104 RICE therapy, 103

INDEX Tucson recluse. See Loxosceles sabina Uloborus, 59 uncate, fang, 19, 19 Uropygida, 5 vacuum cleaner, 158 venom comorbidities, 102 development in spiderlings, 57 sphingomyelinase D, 57–58, 92, 101 toxicity to insects, 58 venom effects (on animals) cat, 109–110 dog, 109–110 guinea pig, 92 mouse, 92 pig, 92 rabbit, 92 rat, 92 venom effects (general terms) anemia, 102, 104–105 blister, 100 blood clots, 101–102 blood flow, lack of, 100–101 bull’s eye wound, 100 coagulation maladies, 93 decrease in blood flow, 100–101 decrease in blood platelets, 106 gangrenous spot, 96 hemoglobin in blood, 93, 105 hemoglobin in urine, 96, 105 hemoglobin loss, 102, 104 itching, 100 jaundice, 105 kidney injury, 105–106 malaise, 105 multiple-organ toxicity, 93, 102 pain , 100–101, 105 rash, 96, 100, 105 red blood cell destruction, 93, 102, 104–106 redness, 100 scab, 98, 100 swelling, 100 tissue removal, 103 ulceration , 100 urine, dark, 105 white blood cell production , 102, 106

white blood cells, 101 yellowing of eyes, 105 yellowing of skin , 105 venom effects (medical terms) anemia, 102, 104–105 arthalgia, 100, 105 bilirubin , 102, 105 bleb, 100 blister, 100 bull’s eye wound, 100 capillary collapse, 101 chemotaxis, 101–102 coagulopathy, 93 complement, 102 cytokines, 101–102 degranulation , 101 dermonecrosis, 98–104 DIC, 102 edema, 100 erythema, 100 eschar, 100 G6PD, 104 gangrenous spot, 96 glucose-6-phosphate dehydrogenase, 104 gravitational flow of wound, 100–101 hemoglobinemia, 93, 105 hemoglobinuria, 96, 105–106 hemolysis, 93, 102, 104–106 hemolytic anemia, 102, 104–105 icteric sclera, 105 ischemia, 100–101 jaundice, 105 LDH, 102 leukocytosis, 102, 106 malaise, 105 multiple-organ toxicity, 93, 102 myalgia, 100 necrosis, 98, 100 petechial eruptions, 105 polymorphnucleocytes, 101 pruritus, 100 rash, morbilliform, 105 rash, scarlatiniform, 96, 105 thrombocytopenia, 106 thrombosis, 101 ulceration , 100 vascular damage, 101 violin pattern , 11, 12, 13, 14–15, 22, 23, 24, 85, 86

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186

INDEX Virginia, distribution , 77 visibility and tangibility, 131–132 Washington (state) distribution , 82 overdiagnosis of bites, 114 Washington D.C., 85–86 Wasserman , Gary, 91, 102–103, 120 webs, 25, 25, 32 West Nile Virus, 74, 129 White, E. B., 33 word-of-mouth, 127

year of significance (medical aspects) 1872, 95 1893, 95 1896, 96 1929, 96 1940, 96 1957, 1, 96, 139 year of significance (naming of species) 1820, 8 1832, 8 1873, 8 1940, 9, 96