Show Me the Spider
Brown recluse spiders, as their name suggest, are shy and secretive creatures. Like 12 other species of recluse spiders, the brown recluse spider has six eyes arranged in pairs. (Most spiders found in the United States have eight eyes.) The spiders average about half an inch (1.3 centimeters) in length and their brown, silky bodies lack any discernible pattern. Fine hairs cover their legs. The nocturnal arachnid uses venom to subdue their prey.
Many diagnoses of brown recluse spider bites come from areas apparently outside of the brown recluse's habitat. Brown recluse spiders are found mostly in the central and southern U.S., an area that includes Texas, Arkansas, Missouri, Kentucky, Tennessee, parts of Illinois, Indiana, and Georgia. Brown recluse spiders also inhabit the states bordering the Gulf of Mexico.
Yet Vetter has fielded reports of brown recluse bites from Wisconsin, New York, even Alaska and Canada. In virtually every case, systematic searches in those places have turned up no brown recluse spiders.
In one analysis, Vetter counted 188 reports of brown recluse bites in three years in California, Oregon, Washington, and Colorado. But only 15 brown recluse spiders have ever been found in those four states. "These bite diagnoses are everywhere, and yet no one can find the spider," Vetter said. "Show me the spider."
Even where brown recluses do live, people overestimate their risk, Vetter said. In one recent case in Kansas, a family of four collected more than 2,000 brown recluse spiders in their house during a six-month period. The family found spiders on the paper towel rack, crawling up the stairs, and lurking in piles of laundry. "There were four people living in that house for six years," said Vetter, who wrote about the case in the November issue of the Journal of Medical Entomology. "Guess how many bites? None."
Vetter and colleagues have recently embarked on a project to census brown recluse spiders in northern Illinois and southern Iowa. Similar studies elsewhere should provide doctors and the public a better understanding of brown recluse spiders.
"These spiders are dangerous and they can cause nasty wounds," Vetter said, "but the perception of the brown recluse as a serious health threat is overstated."
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