Over the course of your life time, the average person eats X spider/insects/whatever whilst they are sleeping.

X tends to vary according to who you ask. Is this just an urban legend?

  • 55
    Zero is a number...
    – fred
    Commented Apr 8, 2011 at 13:25
  • 2
    A spider scientist once told me that there is [almost] always a spider within 8 feet of you.
    – JD Isaacks
    Commented Apr 8, 2011 at 17:31
  • 24
    @John: Or was it that there is always a spider with all 8 feet in you? Commented Apr 8, 2011 at 19:10
  • 12
    I liked the old Dave Barry bit, which was to point out that the 8 spiders a year was an average, and because nobody he knew ate any spiders, it must mean that someone, possibly Donald Trump, was eating millions of spiders to get the average up. Commented Apr 12, 2011 at 16:14
  • 5
    What happens if you eat one while awake, and then it crawls out of you...? Is that eating -1 insects while sleeping? Commented May 12, 2011 at 0:31

4 Answers 4


This is an utter fabrication.

It is thought to have started with an article in PC Professional Magazine regarding ridiculous facts circulating via e-mail.

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.

From Snopes.com

However, the Snopes article itself has been called into doubt, with claims that Snopes made up the reference.

  • 12
    interestingly, citing Lisa Holst and her PC Professional article as the source of the myth has become a bit of a myth itself: eightspiders.com/2008/08/why-eight-spiders.html
    – Oliver_C
    Commented Apr 8, 2011 at 15:39
  • Hmmm...so one person couldn't find a an article written 15 years ago (before everything went online). And Lisa Holst must be a fairly common name. Commented Apr 8, 2011 at 16:05
  • 13
    There is now a question regarding the Lisa Holtz source. Commented Apr 13, 2011 at 23:45
  • 3
    Seriously, I can confirm that there was (maybe still is) a PC magazine called "PC Professionell" ending in the german (latin?) suffix ~ell, not ~al. Here is an ebay auction with a 1991 magazin Here is a press artigcle from 2001. Commented May 14, 2012 at 5:19
  • 1
    That's likely a fake snopes article
    – Sklivvz
    Commented Oct 6, 2016 at 17:10

From Rod Crawford (Curator of Arachnids, Burke Museum)

For a sleeping person to swallow even one live spider would involve so many highly unlikely circumstances that for practical purposes we can rule out the possibility. No such case is on formal record anywhere in scientific or medical literature.

[...] I remain unconvinced that a spider would visit a huge breathing monster and enter its mouth.

Unless a spider is so small that it wouldn't realize that the "hole" is the mouth of a large predator, it's probably unlikely that a spider would crawl into it.

  • I invoke "The theory of large numbers", given enough opportunity even very unlikely events occur in significant numbers. However, as it is probable that someone has in their lifetime swallowed a spider in their sleep, it is still unlikely that on average a human will swallow > 1 spider. Commented Apr 8, 2011 at 14:11
  • 10
    Spiders (and various other invertebrates) can detect high concentrations of carbon dioxide and avoid it, presumably to avoid mouths (and even the skin of large creatures that may crush them accidentally). So spiders, no matter how small, do realize that mouths, no matter how big, are to be avoided. (Incidentally, mosquitos use these CO2 sensors in reverse--instead of running away, they run towards....)
    – Rex Kerr
    Commented Apr 8, 2011 at 23:35
  • 4
    "(Incidentally, mosquitos use these CO2 sensors in reverse--instead of running away, they run towards....)" So how many mosquitoes does the average person swallow a year?
    – tcrosley
    Commented May 15, 2015 at 9:12
  • @tcrosley: Motorcyclist, or non-motorcyclist?
    – DevSolar
    Commented Oct 7, 2016 at 8:41
  • Mites (Alcari) belong to spiders. You sometimes talks about mites the size of 100 to 400 µm. Pneumonyssus simicola is one of them which lives in the lungs of .. apes. So they are activly searching for this "huge breathing monsters"
    – Offler
    Commented Jan 7, 2019 at 11:16

The Straight Dope claims that one person may accidentally swallow a large number of spiders after an egg sac bursts:

Put it all together, and it would be a miracle for a spider to end up in anyone's mouth while they're sleeping, except for one rare circumstance--when a spider egg sac hatches indoors. At that point, you can have hundreds of microscopic spiders, a millimeter long or less, leaping into the air in a short time span (under an hour total) and trying to ride the air currents to freedom.

However, these events should be rare and the author argues that average number of spiders swallowed being so high seems doubtful:

After all, most people breathe while they sleep (at least I do) and spiders, like virtually all arthropods, flee from breath. After all, there are lots of vertebrates that EAT arthropods, and if you're an arthropod and something is breathing on you, it's not a good idea to stick around. Simple enough.

So, it seems unlikely, but the arguments given in this particular article aren't conclusive.


The 1992 book Basic Statistics for the Behavioral Sciences Student Workbook and Study Guide says:

b.This is a very low p, indicating that, over the long run, we can expect to swallow spiders only 5 out of every 10,000 times we sleep.
c. Since p is not zero, we do expect to swallow spiders sometimes, and we don't know when it will happen.

This appears to be just a hypothetical statistics problem, but it could have been easily misunderstood as actually indicating that people swallow a certain number of spiders.

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