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Environment & Science

5 things you didn't know about the brown recluse spider

US penny (L) and a brown recluse spider.
US penny (L) and a brown recluse spider.
Matt Britt/Wikipedia Commons

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Richard Vetter, who has set listeners straight on black and brown widows, and who co-wrote "The PCT Field Guide for the Management of Urban Spiders," has written the first comprehensive book about possibly the most unfairly maligned spider of all: the brown recluse.

(Spider expert Richard Vetter. Image: UCR)

The retired UC Riverside researcher talked with Off-Ramp host John Rabe about his new book, "The Brown Recluse Spider."

From their interview, here are five things you probably didn't know about brown recluse spiders.

1. You weren't bitten by the brown recluse spider and neither was that guy you heard about.

If you live in Southern California, it wasn't a brown recluse that bit you (or that guy) — if you were even bitten — because they simply don't live here (see below). 

[Doctors ] would say, "Well, of course there are brown recluses here, we diagnose the bites all the time." The problem is there are many things that can cause skin lesions that look like recluse bites, about 40 different conditions that we currently know.

Plus, Vetter says they avoid human beings.

People think that if they just have one recluse in their house that this thing is going to be running around like the shark from Jaws, running around chomping on them. I did a study with a woman in Kansas, and she collected, in six months, 2,055 brown recluse spiders in her house. Most of these were babies, and about 400 were of a size big enough to bite, yet it took 11 years before these people had one registered bite in their house.

2. They can slow down their metabolism and live up to 5 years.

They are sit-and-wait predators and can survive without feeding for quite awhile. They just lower their heart rate and they just sit there, if they're sitting away from predators, so they're not going to be running around to get out. They just wait there.

3. They didn't have a bad reputation until the Eisenhower years.

Actually, for years there had been conjecture that these little brown spiders were causing problems. Farmers knew very well that there were some problems in their barns, and they had a pretty good idea that it was a spider that was doing it, but it wasn't until 1957 that it was proven scientifically.

Whenever there is a new spider that is thought to be toxic, the media just jump on this all over the place and everyone gets really excited about things. So what happened after 1957, there was a rush to provide a lot of information to people, just like when the West Nile virus started or Lyme disease, 1977.

4. There aren't any brown recluse spiders in Southern California.

 The brown recluse is one species of spider, which is found in the Midwest. There are no populations of the brown recluse spiders known in Southern California.

We do have the Chilean recluse in a few buildings in L.A. County. They are usually in the basements of municipal or commercial buildings. They are not biting people, and the Department of Health doesn't consider them a concern.

And we also have the desert recluse out in the deserts — Palmdale, Victorville, Blythe, China Lake, Indio — not in the L.A. Basin at all.

5. Richard Vetter's "The Brown Recluse Spider" is the first book about the brown recluse spider.

There really was no source for a lot of people who were not sure of what was going on. This is a book based on scientific information and I think it's going to convince a lot of folks.

But as Vetter admits, we do love our legends. Listen to the audio for much more on the much maligned brown recluse spider.