There are no populations of brown recluse spiders living in California.
Myth of the Brown Recluse by Rick Vetter
Excerpted from the article “Myth of the Brown Recluse” by the preeminent arachnologist Rick Vetter, Department of Entomology, University of California, Riverside, CA
Sources for this article are nationally and internationally respected scientists and with specific knowledge and expertise in the state of California and they include:
- Arachnologists throughout the state including those at the Los Angeles County Museum and San Francisco’s California Academy of Sciences (one of whom is probably one of the top 5 arachnologists in the world)
- The Calif. Dept of Food and Agriculture, which is responsible for identifying all exotic pests found in California
- County Agricultural Commissioner Office entomologists up and down the state
- Hundreds of pest control operators in both Northern and Southern California
- County vector and health personnel
- A U.S. recluse expert, who wrote the definitive taxonomic revision where he described the distribution of all North American recluse species, and who also happened to be a vector control person in Northern California, now retired.
- The late Dr. Findlay Russell, the world’s foremost authority on animal venoms. Dr. Russell was an internationally renowned toxicologist, was a medical physician at USC Medical Center and consulted on hundreds of “spider bite” diagnoses in California. In fact, Dr. Russell’s research was the impetus for many of the ideas expressed here.
Californians-the brown recluse is a myth. There are no populations of brown recluse spiders living in California. In case this upsets your applecart, I repeat, there are no populations of brown recluse spiders living in California. The common name “brown recluse spider” refers to one species of spider, Loxosceles reclusa, which lives in the central Midwest: Nebraska south to Texas and eastward to southernmost Ohio and north-central Georgia (see map). Only a handful of specimens (less than 10) have ever been collected in California and usually there is some connection between the spider and a recent move or shipment from the Midwest.
Yet so far less than 15 verified specimens of the spider have been found in the state of California in the last 40 years.
I have polled California county entomologists, vector control personnel and arachnologists regarding the number of spiders that have been submitted to them by the California public and how many were brown recluses. So far, over several decades, about 20,000 spiders have been turned in by concerned Californians and none have been brown recluses.
This is a brown recluse. They DO NOT LIVE in California.
Rampant recluse phobia is based on the sensationalistic news media who scream about the POSSIBILITY of one spider being found in California. For example, a California county entomologist said that when he found a potential recluse spider, he had 2 television news trucks parked outside his office waiting for him because they wanted to get “THE STORY”. In 1998 or so, there was a rumor that a Marin County park ranger and 2 others were dead from brown recluse bites. People freaked out. One woman called a taxi cab, handed the driver some money and a dead spider and told him to deliver it to the County Agricultural Commissioner’s Office for identification. (Apparently the driver just took the money and drove off, never delivering the spider.) No park ranger died and it was just hysteria.
Although there is the chance a brown recluse could be in California, that one little spider is not responsible for the several hundred brown recluse spider bite diagnoses that have been made in California and the probability of being bit by a brown recluse in California is realistically zero.
In its native range, the brown recluse is a very common house spider. A colleague in Missouri found 5 in a child’s bedroom one night, a person in Arkansas found 6 living under his box spring in his bedroom, and an 8th grade teacher in Oklahoma discovered while checking up on his students on their insect collecting trip that in about 7 minutes, 8 students collected 60 brown recluses- picking them all up with their fingers and not one kid suffered a bite.
In Tennessee where they have brown recluses, a bite victim brings a brown recluse spider to the doctor about 20% of the time.
The myth of the brown recluse reinforces the misconception to the California medical community that the brown recluse lives here whereupon they make misdiagnoses. In “alleged brown recluse spider bites” in California, almost never is any species of spider collected nor identified in the incident and if it is, never has it been a verified brown recluse. There are many different causative agents of necrotic wounds, for example: mites, bedbugs, a secondary Staphylococcus or Streptococcus bacterial infection. Three different tick-inflicted maladies have been misdiagnosed as brown recluse bite: Lyme disease, Rocky Mountain Spotted Fever and the bite of the soft tick, Ornithodoros coriaceus.
Every month in California, more people are diagnosed as having brown recluse bites than the total number of brown recluse spiders EVER collected in the state. -Rick Vetter
People in California often mistake the essentially harmless Wolf Spider for the brown recluse.
Wolf spiders will inject venom if continually provoked but the symptoms of their venomous bite are relatively mild and include swelling, mild pain, and itching. They are not an aggressive species and just want to be left alone, so they can continue to do their part for the ecosystem and hunt smaller insects, many of whom are considered pests by humans. If you find one in your house, just catch it in a cup and release it outside.