Dreaded Brown Recluse: Fact or Fiction?

Have you ever been bitten by a brown recluse spider? No? Then you seem to be in a minority of Americans.

For years now, friends and acquaintances in all parts of the country have told me about how they, or someone they know, was bitten by a brown recluse. Some victims became seriously ill. One or two died. I heard that there is hardly a bedroom curtain or a bath towel hamper that doesn't harbor a lurking arachnid, eager to feast on human flesh.

But don't repeat this to Richard S. Vetter, an entomologist at the University of California, Riverside. He and his colleagues have been looking into such reports for years, and report that most of them (including those certified by doctors) are bunk.

"The brown recluse spider is rarely found outside of its endemic range (southeastern Nebraska to southernmost Ohio, south to Texas and Georgia)," Vetter has written. "The annual number of medical diagnoses of brown recluse bites in many non-endemic states or regions is ten to hundreds of times greater than the historic total of verified brown recluses in the area."

It's true that occasional members of that species show up in other areas-Florida, Illinois, Maine, for example-but usually as individuals or in isolated, transient populations. Valid reports of bites exist, resulting in pain and necrosis (death of surrounding cells or tissues). But, as Vetter points out, "Rarely is a spider seen inflicting the wound, or captured while biting, and it is difficult to either prove or disprove spider participation in the event."

Vetter argues that the cause of the wound is often misdiagnosed, and a faulty explanation can be disastrous. Spiders aren't programmed by evolution to bite warm-blooded mammals, including us. But many kinds of insects, including ticks, fleas, and assassin bugs actively seek blood meals. A doctor who thinks of spider bites first may be missing an even more serious condition, such as a staph infection, herpes, Lyme disease, cell carcinoma, or localized vasculitis.

Alas, the reputation of the brown recluse may cause far more grief than the spider itself.

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