Myth of theBrown RecluseFact, Fear, andLoathingHigh Desert State Prison Medical EducationFrom publications from the Department of Entomology, University ofCalifornia, Riverside, CA and the Calif. Dept of Food and Agriculture
Department of Entomology, University of California, Riverside, CA“This website presents evidence for the lack of brown recluse spidersas part of the Californian spider fauna. Unfortunately, thiscontradicts what most Californians believe; beliefs that are born outof media-driven hyperbole and erroneous, anxiety-filled publichearsay which is further compounded by medical misdiagnoses.Although people are free to disagree, this opinion has come aboutafter more than a decade of constant research. In addition topersonal experience, the sources for this opinion encompassesconversations with, interactions with, and the cumulative knowledgeof the following, who have experience or expertise in the state ofCalifornia and, in some cases, are national or international experts:Arachnologists throughout the state including those at the Los AngelesCounty Museum and San Franciscos California Academy ofSciences (one of whom is probably one of the top 5 arachnologistsin the world)The Calif. Dept of Food and Agriculture, which is responsible foridentifying all exotic pests found in California”
County Agricultural Commissioner Office entomologists up and downthe stateHundreds of pest control operators in both Northern and SouthernCalifornia County vector and health personnelTHE U.S. recluse expert, who wrote the definitive taxonomic revisionwhere he described the distribution of all North American reclusespecies, and who also happened to be a vector control person inNorthern California Dr. Findlay Russell, the worlds foremostauthority on animal venoms. Dr. Russell is an internationally renowntoxicologist, was a medical physician at USC Medical Center andconsulted on hundreds of "spider bite" diagnoses in California. Infact, Dr. Russells research was the impetus for many of the ideasexpressed here. Cumulatively, this body of knowledge representshundreds of years of experience with spiders and/or their medicalaspects in California and the identification of hundreds of thousandsof spiders. So if you think the material here is in error, consider thestrength of your own sources.
Spiders are one group of arthropods that are very well known by the commonperson yet are terribly misunderstood; because of the rare occasion of adeleterious venom incident, almost all spiders are lumped into the categoryof "squish first and ask questions later". There are remarkably few spiders inCalifornia that are capable of causing injuries via biting. Overall, spiders arebeneficial to humans in that they eat many pestiferous insects that eitherinfest our foods (many phytophagous insects), are vectors of disease(flies,mosquitoes) or are aesthetically-challenged (cockroaches, earwigs).Unfortunately, humans have a low tolerance for spiders in their homes,either because spiders are symbols of danger, unkemptness orarachnophobia. One of the first steps one should take in dealing with thesecritters should be to identify them properly before blasting them withpesticide and/or getting hysterical.There are no sure long-lasting control measures for spiders, however,mostly what pest control operators are dealing with in this situationis a psychological problem rather than an entomological one. Folkswant spiders out of their homes because of fear and/or repulsion.The assumed risk of spiders in ones home is much greater than theactual risk they pose and home owners probably do more harm tothemselves by using large amounts of pesticides inside a home tokill spiders than any harm the spiders could actually do to them.Unfortunately, the quantities and habits of spiders cause them toreinfest areas soon after treatment so it is difficult to eliminatespiders altogether.
The spider that poses the greatest health threat to humans in Californiais the black widow spider, Latrodectus hesperus. Before antivenomwas available, bites from these spiders caused death in about 5% ofthe cases. Currently there are adequate medical treatments; deathsfrom black widow bites are virtually non-existent. This adult femalespider is readily identifiable because of its unique coloration: a shinyblack body with red hourglass on its belly (not on its back as lots ofpeople think). However, the western black widow looks verydifferent as an immature because it starts out life bedecked in tanand white stripes. As spiderlings mature, more black pigmentation isdeposited in the integument with each molt until they turn completelyblack. Males retain the coloration of the juvenile striped pattern andare often turned into our department because folks are afraid thatthey are brown recluses. The next "spider" most familiar toCalifornians-the brown recluse-is a myth. There are no populationsof brown recluse spiders living in California. In case, this upsetsyour applecart, I repeat, there are no populations of brownrecluse spiders living in California. The common name "brownrecluse spider" refers to one species of spider, Loxosceles reclusa,which lives in the central Midwest: Nebraska south to Texas andeastward to southernmost Ohio and north-central Georgia.
Only a handful of specimens (less than 10) have ever been collectedin California and usually there is some connection between thespider and a recent move or shipment from the Midwest. There is agreat "awareness" of brown recluse spiders in California mostlythrough a misguided media barrage which is fed by a fear of theunknown and unfamiliar.• I repeatedly have seen the media in their "quest to seek out thetruth" write completely speculative stories about the existence of thebrown recluse in California. Unfortunately, the truth is not nearlygood enough to sell news and therefore, a speculative story isfabricated based upon faulty assumptions. Rampant recluse phobiais based on peoples willingness to believe the worst about asituation and the sensationalistic news media who scream about thePOSSIBILITY of one spider being found in California. Actual titlesfrom newspapers regarding recluse stories are "Necrotic WoundBlamed on Elusive Spider" , "Spider-bite Terror in Calif.", "Likely Biteby Spider Changes Life". Notice how carefully the titles are chosen.They dont say that they have found the spiders or that a populationof the spider has been verified. They report the belief that thespiders are here or have caused damage. The brown recluse is theRichard Jewell of the spider world.
• Many times the speculative stories are based on the premise that abrown recluse COULD be found in California. While this is certainlytrue (since people move from the Midwest each day), it is also truethat because I am a male, I could have an illicit and immoralrelationship with a Playboy bunny. This is definitely a possibility.However the chasm between "POSSIBILITY" and "PROBABILITY"is so wide you couldnt build a bridge between here and there. Amore tenable example is that someone COULD win the Californiastate lottery grand prize by buying one ticket a year. This isdefinitely a possibility. However, the probability of this is obviouslyso close to zero that it is effectively zero. As they say, the lottery is atax on those bad in math. Still there are many more California lotterygrand prize winners than brown recluse spiders found in the stateeach year. Although there is the chance a brown recluse could be inCalifornia, that one little spider is not responsible for the severalhundred brown recluse spider bite diagnoses that have been madein California and the probability of being bit by a brown recluse inCalifornia is realistically zero.
Yet the finding of one alleged brown recluse in California is enough toget the news hounds barking for a story. A In its native range, thebrown recluse is a very common house spider. A colleague inMissouri found 5 in a childs bedroom one night, a person inArkansas found 6 living under his box spring in his bedroom, duringa cleanup at the Univ. of Arkansas, 52 were found in a science labthat was being used everyday, a colleague found 9 living under onepiece of plywood in Oklahoma, a grad student and I collected 40 ofthem in a Missouri barn in 75 minutes, and would have collectedmore, but we ran out of vials to house them. One amazing story isan 8th grade teacher in Oklahoma checking up on his studentsavidly collecting material by some loose bricks around a flagpole onan insect collecting trip. In about 7 minutes, 8 students collected 60brown recluses, picking them all up with their fingers and not one kidsuffered a bite. An even more amazing story is that of a woman inLenexa, Kansas who collected 2,055 brown recluse spiders in 6months in 1850s-built home. This family of 4 has been living there 8years now and still not one evident bite. (see Vetter and Barger2002, Journal of Medical Entomology 39: 948-951). When you findbrown recluses in an adequate environment, you do not find one,you find dozens. And yet, the people who live with these spidersrarely get bitten nor do they run around in constant fear.
With the current paranoia, if we had populations like that in California,they would evacuate the state and close it down. The Californiareaction to the mythical brown recluse is based solely on the fear ofthe unknown and the willingness to believe that there is an 8-leggedmenace running around causing havoc. I was interviewed by a localnewspaper reporter looking for a sensationalistic sound bite. Thequestion was, "What do you think the effect of this brown recluseevent will have on southern California?" My answer was "All thetourists from Missouri, Arkansas and Kansas are laughingthemselves off their hotel beds because a story on one allegedbrown recluse spider found in Los Angeles makes the eveningnews."California county entomologist said that when he found a potentialrecluse spider, he had 2 television news trucks parked outside hisoffice waiting for him because they wanted to get "THE STORY". In1998 or so, there was a rumor that a Marin County park ranger and2 others were dead from brown recluse bites. People freaked out.One woman called a taxi cab, handed the driver some money and adead spider and told him to deliver it to the County AgriculturalCommissioners Office for identification. (Apparently the driver justtook the money and drove off, never delivering the spider.) No parkranger died and it was just hysteria. Other news articles aboundwhen there is the "thought" that a brown recluse might have beenfound in California.
How ludicrous do you think this looks to the rest of country? How hardis that Arkansas guy laughing who was sleeping on top of 6 brownrecluses? How much head-shaking does the woman in Nashville dowho collected 7 running through her apartment in one month? Howabout the Kansas arachnologist who found 12 under a rug in adoghouse? (Actually, he does laugh pretty hard every time I relate aCalifornia brown recluse paranoia story to him.) How about theOklahoma kids who each collected an average of 1.07 brownrecluses per minute where it would take the average kid in thatgroup 8 minutes to collect more brown recluses than has the entireCalifornia populace (currently about 32 million people) in 40 years?People get all worked up and say, "BUT IF THEY FOUND ONEBROWN RECLUSE IN CALIFORNIA THAT MEANS .." It meansthey found one, it is smashed, mangled, mutilated, pickled inalcohol, dead, deceased, passed on, no more, ceased to be,bleeding demised, bereft of life, resting in peace, gone to meet itsmaker, pushing up the daisies, rung down the curtain and joined thechoir invisible, etc. and no longer poses a threat to humanity (notthat it posed a great threat to begin with).
THIS is an ex-spider! Brown recluses are almost communal and can befound in great numbers. If you truly have a brown recluse infestationin your house or your community, then you should readily be able tofind dozens more with little effort. Once again, every few years abrown recluse can be found in the state but it is a single itinerantthat was brought here, is not the tip of a massive invasion and doesnot justify hundreds of medical misdiagnoses, hyperbolic newsstories nor public hysteria. If they truly lived here then you should beable to find many specimens for identification. Finally, despite all myantagonism, I fully realize that someday someone somewhere mayfind a thriving population of brown recluse spiders living inCalifornia. But to date, this has not happened despite 1) theoverwhelming public concern about the presence of this spider inthe state, 2) the false belief that it already is here and causingmassive damage and 3) the voluminous collections, spanningseveral decades and including hundreds of thousands of spiders, bymany arachnologists, amateur and professionals alike. One reasonfor my verbal assault is that I want to get folks as incensed aboutfinding a real brown recluse as I get incensed about all these folkstelling me that brown recluses are everywhere.
It is really amazing that wherever I go (the supermarket, dentalappointments, on campus, etc.) any place where one makes idlechit-chat, folks are always telling me that they have found brownrecluses, are afraid of brown recluses, have been bitten by brownrecluses, have had neighbors die or lose limbs to brown recluses.The brown recluse has been elevated to a major urban legendstatus very much like UFOs, Bigfoot and Elvis. There is this mythicalcharacteristic about their legend and the fear they invoke such thatthe majority of people I run into in California are either convincedthat brown recluses live here or are surprised to find out that theydont. The biological evidence that is available resoundingly deflatesany of the arachno-propaganda that is constantly being given newlife with each newspaper story or word-of-mouth tale of terror. Iemphatically state THERE ARE NO BROWN RECLUSE SPIDERSLIVING IN CALIFORNIA.
Close-up of cephalothorax head region of desert recluseshowing typical arrangement of eyes.
The head region (cephalothorax) and abdomen of a brown recluse,Loxosceles reclusa (left), and a desert recluse,Loxosceles deserta. Note the characteristic spacing of the sixeyes arranged in three dyads. The violin marking is well definedon the brown recluse but is very faint on the desert recluse.
Spiders Commonly Confused with Recluses• Because of the misinformation surrounding the brown recluse‘s presence inCalifornia, many spiders that are virtually harmless are submitted by thepublic for identification. Most of them are not from the recluse family andsome are not even spiders. A nationwide study was undertaken from 2000to 2005, offering to identify any spider that was considered to be a brownrecluse spider. Nearly 600 specimens were submitted from California, manyfrom people who were adamant that they had a brown recluse. Only one ofthese specimens was a brown recluse, from a house where the family hadmoved from Missouri. No additional recluses were found in the house. Theoccasional finding of a translocated spider is not overly surprising, however,it still does not happen often. There were 17 desert recluses in this study, allsubmitted from the desert regions of southeastern California where thespiders are known to occur. Yet nonrecluse spiders were submitted in greatnumbers including many false black widow, woodlouse, and yellow sacspiders. Presented below are descriptions of spiders that share some of thesame physical features as the brown recluse and have been misidentified asrecluse spiders
• Six-Eyed Spiders• Spitting spiders (Scytodes spp.) are closely related to reclusespiders and have six eyes arranged in a similar pattern. However,they also have many black spots or lines on their bodies that wouldexclude them as recluses. Unlike the recluse, the woodlouse spider,Dysdera crocata, has six eyes arranged in two groups of three(triads) and no bodily markings.• Spiders with Violin-Shaped or Other Dark Markings• Many common tan or gray spiders have dark markings on the headregion, which convinces people that they have caught a bona fiderecluse spider. These spiders include cellar spiders (Pholcusphalangioides, Psilochorus spp., Physocyclus spp.), pirate spiders(Mimetus spp.), and sheet web spiders (Linyphiidae). The marbledcellar spider, Holocnemus pluchei, also confuses people eventhough the dark marks are on the ventral (underside) not the dorsal(top) surface of the body. Another frequent submission is Zoropsisspinimana, which is found only in the San Francisco Bay area and isa harmless Mediterranean immigrant established in Sunnyvalearound 1995. It is large, frequently found in homes, and Bay Arearesidents see the dark marking on the top surface of the abdomenas a violin which is the wrong body part to be sporting the violinmarking in order to be identified as a recluse.
• Ubiquitous Brown Spiders• Virtually every spider that is tan or brown has been turned in as apotential brown recluse. There are hundreds of species of thesespiders in California. They include ground spiders (Gnaphosidae),sac spiders (Cheiracanthium spp., Trachelas spp.), wolf spiders(Lycosidae), grass spiders (Agelenidae), orb weavers (Araneidae),and male crevice spiders (Filistatidae). More specifically, males ofboth the western black widow (Latrodectus hesperus) and the falseblack widow (Steatoda grossa) are frequently brought in for recluseverification. One of the most common submissions as brownrecluses are spiders in the genus Titiotus, which are found just northof Los Angeles, through central California to Redding and arecommonly found in redwood forests. Titiotus spiders have a hairpattern that gives the impression of a violin and its coloration issimilar to that of a brown recluse. All of these brown spiders haveeight eyes and can quickly be eliminated from consideration.
AMERICAN RECLUSE SPIDERS• Eleven species of recluse spiders are native to the United States and two non-nativeshave become established in certain highly restricted areas of the country. The brownrecluse spider is the proper common name for only one species, Loxosceles reclusa.It is the most widespread of the North American recluse spiders and lives in the southcentral Midwest from Nebraska to Ohio and south through Texas to Georgia.Although the brown recluse does not live in California, we do have four species ofnative recluse spiders. The most common Californian recluse spider is the desertrecluse, Loxosceles deserta. It is found mostly in the Sonoran and Mojave deserts, inthe foothills of the lower San Joaquin Valley, and in adjacent areas of Mexico; most ofthese areas are sparsely populated by humans. In older literature, this spider wasreferred to as Loxosceles unicolor. There are additional species (Loxosceles russelli,Loxosceles palma, Loxosceles martha), but they are so uncommon that they are ofscientific interest only.• In addition to these native species, the Chilean recluse spider, Loxosceles laeta(pronounced “LEE-ta”), has become established in portions of Los Angeles(Alhambra, Sierra Madre, Monterey Park, San Gabriel). This spider, however, seemsto be confined to a very limited area in Los Angeles County even though it has livedthere for possibly over 70 years (one specimen collected from Los Angeles in 1936 ishoused in Chicago’s Field Museum spider collection). Also, occasional interceptionsof the Mediterranean recluse, Loxosceles rufescens, are found in commercial goodsshipped from out-of-state, but no populations of this spider are currently known inCalifornia.
Non-abundance of Brown Recluses in California• Unlike many other spiders that disperse by either migrating or being carriedby air currents when small (“ballooning”), recluse spiders can expand onlyoutside their native range as a result of human intervention. The few brownrecluses that have been collected in California typically are found in facilitiesthat receive goods from out of state or are unintentionally transported bypeople who have moved from the Midwest. In these instances, searchingthe immediate area yielded no additional brown recluses so they wereconsidered to be individual stowaways. Undoubtedly, more brown recluseshave been inadvertently brought into the state via commerce and therelocation of household belongings; however, amazingly few specimenshave ever been collected. Never have any of these translocated spidersbeen able to establish a foothold and start a population in California.Considering that brown recluse spider bites are not common in the south-central Midwest where brown recluses frequently cohabit with people, it isclear that California does not have anywhere near sufficient populations ofthese spiders to be responsible for the number of cases or illnesses that areattributed to them. The problem of misdiagnosis is widespread in NorthAmerica, including such unlikely places as Alaska and Canada wheredoctors have attributed skin lesions to recluse bites when no brown reclusespiders have ever been found north of the 48 contiguous U.S. states.
• Potential Toxicity of Bites• All Loxosceles spiders tested so far have the venom component thatis capable of causing necrotic skin lesions, so it is best to assumethat all recluse spiders may be capable of causing skin damage. Ingeneral, the desert recluse spider’s venom is similar to that of thebrown recluse and should be considered of equal potency. Incomparison to the brown recluse spider, the Chilean reclusesupposedly has venom more potent and the Mediterraneanrecluse’s venom has been said to be less potent. However, thesecomparisons are more anecdotal than quantitive assessments.• About 10% of brown recluse bites cause moderate or greater tissuedamage and scarring, but the vast majority heal very nicely withoutmedical intervention. There is still not one proven death from brownrecluse bite (a person was bitten by a spider caught in the act andproperly identified). While there are several highly probable deathsreported in children, these are extremely rare occurrences, aboutone every decade or so.
MEDICAL MISDIAGNOSES• One reason for the great awareness of the recluse spiders throughout North Americais that necrotic (rotting flesh) wounds are commonly misdiagnosed as “brown reclusebites.” Although recluses can cause these types of wounds, the biological datainvolving the distribution of the spider indicate that most of these diagnoses areincorrect. A world-renowned toxicology physician who worked at University ofSouthern California Medical Center estimates that most general spider bites inCalifornia referred to him were actually the work of other arthropods and that 60% of“brown recluse spider bite” diagnoses came from areas where no Loxosceles spiderswere known to exist. This is a serious problem in that several medical conditionsmisdiagnosed as recluse bites can lead to debilitating and potentially fatalconsequences. For example, group A Streptococcus infection, sometimesmisdiagnosed as a brown recluse bite, has a fatality rate that can vary from 20 to 80%depending on how quickly it is correctly diagnosed. In serious cases death can occurin a few days.• Additionally, many people diagnosed as having brown recluse bites in California aretreated with antibiotics. The recommended treatment for most actual brown reclusebites (the ones that do not become traumatic) is simple first aid: RICE therapy (Rest,Ice, Compression, Elevation). Antibiotics work against bacteria and have no effect onspider venom. However, regardless of the causative agent, it is wise to seek medicalattention if you feel that it is warranted.
Distribution of the desert recluse, Loxosceles deserta (shaded area) and aSouth American recluse spider (dot), Loxosceles laeta, in California.
The Brown RecluseLoxosceles reclusa• Brown body with a violinshape on abdomen.• Hemolytic venom.– Destroys tissue.– Mild to serious bite.• Rarely dangerous.
On the brown recluse, notice sixeyes, in three pairs of two (triads).
Do Brown Recluse occur in California?• The answer is NO.• There is no• evidence of• brown recluses• in California.
This is Rick Vetter• UCR Entomologist• He has spent his entire careertrying to de-bunk this myth.• If interested:http://spiders.ucr.edu– Swanson, D. L. and R. S. Vetter.2005. Bites of brown recluse spidersand suspected necrotic arachnidism.New Engl. J. Med. 352:700-707.– Multiple other publications.– His “bets” are world famous.• He has yet to lose a bet.
The brown recluse, however,can cause damage…• The hemolytic toxin can cause necrosis oftissue.– This causes the tissue to decompose.– This can cause major damage.• The next slide has two photographs ofactual brown recluse spider bite victims.
SPIDERS• More than 35,000 species of spidersoccur in the world. Of these, about3,400 species in 64 families are foundin North America.• In North America, primary concernsare the Black Widow and BrownRecluse.
Spiders in the USA• Black Widows• Brown Recluses
The Black Widow• The most venomousspider in North America.• Generally not deadlyunless victim is veryyoung or old.• Identifiable by shinyblack body and red“hourglass” on belly.• Relatively small, usuallyaround 1.5” in size.
Where They Live• Seldom disturbedareas• Stock piles• Storage Areas• Shoes left outside• Basements/Attics• Freshly clearedsites• Cobwebs can be asign (but notalways)
The BITE• Venom is 15 times more potentthan that of a rattlesnake(relatively much less isinjected).• Only 63 deaths were reportedin the United States between1950 and 1989• Bite is often not painful andmay go unnoticed at first.• Symptoms include: abdominalpain similar to appendicitis, painto muscles or the soles of thefeet, alternating salivation anddry mouth, paralysis of thediaphragm, profuse sweatingand swollen eyelids.
Treatment• If Bitten:-Apply ice pack to bitelocation and keep elevatedto about heart level.-Try to collect spiderspecimen in jar or bag forpositive identification andtreatment (even if you havecrushed it)-Call the Poison ControlCenter for more info:1-800-222-1222-Bite can be very painful,victim should go to doctorimmediately for treatment.
Bite Prevention• Be Careful!• Wear Gloves and Pay Attention to whereyou put your hands and feet (check yourboots!).• Remove all materials where they mighthide.• Knock down webs, egg sacks and spiders.• This spider is resistant to insecticides.• Avoid storing materials outdoors for anextended period of time.
The Brown Recluse• Identifiable by “violin” on back.• ¼” to ½” long.• Dark brown, yellow, or greenish-yellow• Nocturnal• Likes to hide in small dark areas• Attracted to areas with lots of insects(i.e. near outdoor artificial lighting).
Where They Live• Dark, undisturbedplaces.• Often incardboard boxes,clothing, shoes,and behindfurniture.• Also beneathlogs, loosestones, andstacks of lumber.
The BITE• Some may not be aware ofthe bite for 2-8 hrs.• Many bites cause just a littlered mark that heals withoutevent.• For some, the venom kills thetissues (necrosis) at the siteof the bite.• Can result in a painful, deepwound that takes a long timeto heal (can be deadly for thevery young and old).• Can also cause a “volcanolesion”.
First Aid• If bitten, remain calmand seek immediatemedical attention.• Collect spider forpositive identificationand proper treatment.• Rubbing alcohol canhelp preserve what isleft of the spider.
Harmless Brown Recluse Look-alikesWolf Spider Southern House Spider
Bite Prevention• Check boots, gloves, tool belts, etc. beforeuse.• Wear gloves when handling lumber, rocks,landscape trimmings, etc.• Exercise care when handling cardboardboxes (they are often found in the spaceunder the folded cardboard flaps).
Spider Control• Recluses and Widows are very resistant tocommon insecticides.• In fact, recent studies have shown thatinsecticides can worsen spider problems sinceRecluses tend to be scavengers and are drawnby the high numbers of killed insects.• Make sure the chemical you use is designed toeliminate these spiders.• Good housekeeping and “Just-In-Time” deliveryare great ways to reduce the presence ofspiders.
Spiders and OSHA• OSHA regulations do not go into detail withspiders.• 1926.21 - In job site areas where harmful plantsor animals are present, employees who may beexposed shall be instructed regarding thepotential hazards, and how to avoid injury, andthe first aid procedures to be used in the eventof injury.• 1926.250 (c) - Storage areas shall be kept free1926.250 (c) - Storage areas shall be kept freefrom accumulation of materials that constitutefrom accumulation of materials that constitutehazards from tripping, fire, explosion, orhazards from tripping, fire, explosion, or pestpestharborageharborage..
Related Websites• Brown Recluse Information:• http://www.brownreclusespider.org/• http://www.desertusa.com/desert-animals/brown_spider.html• Black Widow Information:• http://www.desertusa.com/july97/du_bwindow.html• http://doyourownpestcontrol.com/black_widow_spider.htm• http://www.badspiderbites.com/black-widow-spider.php