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Myths about "Dangerous" Spiders

Myth: A spider bit me while I was asleep. (No, I didn't see any spider, but what else could it have been?)

Fact: The notion that "if you didn't see what bit you, it was a spider" is (to me) one of the strangest of the widespread spider superstitions. Even some physicians, who really should know better, accept it! I have no idea how this belief originated, but it is quite false.

Here are some facts: Unless you are sleeping on the basement floor, a spider might wander onto your bed as often as twice a year. Not every night! If you take elementary precautions like not letting the blankets or bedspread touch the floor or walls, the incidence of spiders on the bed will be effectively zero. If a spider does get on a bed, usually no bite will result. Spiders have no reason to bite humans; they are not bloodsuckers, and are not aware of our existence in any case. If you roll over onto a spider, most likely the spider will have no chance to bite.

True spider bites (which are rare events) occur when a spider is trapped inside clothing or when someone foolishly puts a hand or other body part in a spider habitat without looking, or even more foolishly slaps at a spider that is crawling on them. Bites noticed in the morning are generally caused by bloodsucking insects such as fleas, bedbugs, kissing bugs, lice, or assorted flies; less commonly by mites or ticks. Mechanical irritation, allergies and various disease conditions (see this article for a partial list) also cause bitelike sores.

Myth: How could insects be biting me? I see only spiders in the house!

Fact: Ah, but spiders are exclusively predators. Essentially all the food a spider consumes in its lifetime is other small living creatures, mainly insects. House spiders may be more conspicuous than household insects, but they could not live there without insects to eat. And if they were not there, there'd be a lot more insects!

Text © 2003, Burke Museum of Natural History & Culture, University of Washington, Box 353010, Seattle, WA 98195, USA Phone: 206-543-5590 Photos © as credited

Queries to Spider Myths author, Rod Crawford This page last updated 12 May, 2005 This site best viewed at 800 x 600 using IE 5.0 or above.