(The Book of Deadly Animals is now available in the US. I’m going to celebrate by running here an expanded version of a story from the book.)
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It's hard to say how many people have been hurt by hobo spiders, because spider bites are remarkably difficult to diagnose. Part of the problem is that they often don't hurt enough at first to draw any notice. Even in the case of bites that develop serious symptoms like the ones I described above, it is unusual for the victim to bring in the guilty spider. Often the supposed spider bite is just a wound or sore of unknown origin. It's been estimated that 80% of the so-called spider bites physicians treat are really something else entirely—the bites of lice, fleas, or ticks; the symptoms of diseases like Lyme disease and tularemia; strep or staph infections developing around minor scratches. Even eczema or a too-vigorously scratched mosquito bite may cast aspersions on some innocent arachnid. When several Americans came down with skin lesions in 2001, symptoms eventually attributed to anthrax spread by terrorists, doctors first suspected brown recluse spiders.
Why do spiders so often get the blame? Part of the answer seems to lie in arachnophobia. People who notice a sore and, separately, a spider in the house may jump to the wrong conclusion. Serious arachnophobes often report the feeling, which they themselves may recognize as irrational, that spiders are malicious, trying to frighten and harm human victims. Even people without a full-blown phobia will sometimes fall into this way of thinking. In fact, most spiders, if they're capable of biting people at all, only bite in defense of self, eggs, or territory, but many people aren't aware of, or even interested in, that fact.
Another source of confusion is folklore. Stories of venomous arthropods circulate so frequently that scientists tend to dismiss them out of hand. Around 2001, I received emails warning of "blush spiders," tiny but deadly red spiders that hide under the seats of toilets on airplanes ready to bite the unwary traveler on his or her most sensitive parts. There's actually no such thing as a blush spider. Its "scientific name," Arachnius gluteus, which would seem to translate into something like "butt spider," is an easy tip-off.
In 2004, I received anxious queries about "camel spiders," accompanied by a shocking photo of a massively-fanged monster as long as a man's leg. The camel spider, it was said, habitually runs along under camels, leaping up to feast on the flesh of their bellies. Its venom was said to dissolve flesh rapidly. It was claimed that these creatures represented a deadly menace to soldiers at war in Iraq. In fact, camel spiders are harmless, though scary-looking. They are known variously as sunspiders and windscorpions, but are really a little-known arachnid family unto themselves, the solfugids. The largest solfugids in the world are about the size of a woman's hand, which is certainly awe-inspiring, but a mere fraction as large as the trick of perspective in the well-circulated internet photo suggests. Solfugids don't bite people—their mouthparts aren't hinged the right way, so it's the next thing to physically impossible—and they don't pack toxin. Since their fangs are so massive for their size (proportionally the largest in the animal kingdom), they rely on mechanical injury to kill their prey, not venom.
These are only two examples of the folkloric nonsense about arachnids constantly in circulation. Another bit, from the Middle Ages, held that spiders spread the Black Death that killed a third of the population of Europe. It's been suggested that this myth underlies the arachnophobia so prevalent in Western culture.
With such drivel perpetually in the air, it's not surprising that many scientists and doctors have dismissed more credible claims out of hand.Next: Shaved Rabbits