The “you eat X number of spiders” factoid changes depending on who you ask. Some people says it’s three, others eight, and still others might say as many as several dozen. Ask someone who really knows their spiders, though, and the number of ingested creepy crawlies drops right to zero.
Think about it this way, says Rod Crawford, Curator of Arachnids at Seattle’s Burke Museum and a dedicated buster of spider myths: To swallow even just one spider in your sleep, a number of very unlikely circumstances all have to happen at once.
The first, Crawford says, is that your mouth needs to be open. Sure, some people sleep that way, but not everyone. No open mouth, no swallowed spiders.
Second, the spiders have to get in your bed. “A totally normal, neatly made bed,” Crawford says, “has maybe one or two spiders cross it per year.” Add some humans to the bed, and spiders really don’t want anything to do with it. “Most people roll around in their sleep,” write doctors Aaron Carroll and Rachel Vreeman in their book, Don't Swallow Your Gum!: Myths, Half-Truths, and Outright Lies About Your Body and Health. “This rolling would probably scare the spiders from wandering anywhere close to your face.”
Third and fourth, Crawford says, the spider would have to just happen to cross your body where your mouth is and be so bold as to enter an orifice that’s exhaling warm breath. “Just try blowing on a spider and see how they react to that!” Crawford says. “It’s not attractive to them!”
Finally, you’d have to swallow the spider while sleeping, and Carroll and Vreeman point out that, “we do not automatically swallow every time something goes into our mouths.”
The odds are pretty clearly stacked against you swallowing any one spider, let alone multiple ones over the years. “The chance that all of these things would happen together—that there would be a wandering, potentially suicidal spider in close vicinity to your mouth and that they would actually wander in to the wet dark breathing space and trigger your swallowing reflex,” Carroll and Vreeman write, “is really incredibly small.”
However unlikely, something like this still could happen, but we don’t have any solid proof that it has. Plenty of people watch other people sleep, says Crawford, but he’s never seen or heard a single good eyewitness account of a spider climbing into a sleeping person’s mouth or of someone watching them sleep keeping it from almost happening.
What’s more, says Crawford, “Every time you hear this story, the teller has a different number of spiders and a different length of time in which they are supposed to be swallowed. So even if one version had been correct, nearly all the tellers would still have to be lying!”
But Wait, There’s More!
There might actually be another layer of BS to this urban legend. Many stories that debunk the spider statistic point to an article written in the early 1990s about misinformation on the early World Wide Web as its origin. The article on the spider story at Snopes.com, for example, reads:
Fear not. This "statistic" was not only made up out of whole cloth, it was invented as an example of the absurd things people will believe simply because they come across them on the Internet. In a 1993 PC Professional article, columnist Lisa Holst wrote about the ubiquitous lists of "facts" that were circulating via e-mail and how readily they were accepted as truthful by gullible recipients. To demonstrate her point, Holst offered her own made-up list of equally ridiculous "facts," among which was the statistic cited above about the average person's swallowing eight spiders per year, which she took from a collection of common misbeliefs printed in a 1954 book on insect folklore. In a delicious irony, Holst's propagation of this false "fact" has spurred it into becoming one of the most widely-circulated bits of misinformation to be found on the Internet.
All well and good, except that a web search doesn’t turn up much of anything about Lisa Holst or PC Professional that isn’t directly related to the genesis of the spider myth and saying pretty much the same thing as Snopes. The columnist, the column and the magazine don’t seem to exist, or were at least lost to history before everyone and everything had some presence on Google. A few people, including a guy named Nick who runs the blog “Eight Spiders,” have gone a little further in search of the source, but to no avail. Even the Library of Congress said they had no record of the magazine when Nick called them up. The story about how the story got made up may itself be made up. Whoa. Meta.