Gnats in my eyes!

August 29, 2006 12:54 PM

Why do gnats fly into my eyes?

Mosquitoes are annoying, but ultimately forgiveable: they *need* to bite animals like me to make more mosquitoes. But gnats fly around my head for no apparent reason, and seem especially inclined to fly into my eyes and mouth.

I mean, what gives? It hardly seems like good survival strategy on their part. Why do gnats fly around the heads of people and other animals, and why do they with such regularity fly right into their own doom as they harass my head?

posted by washburn to science & nature (7 comments total)

They fly around your head because they're attracted by your exhaled carbon dioxide. You signify the potential for a juicy snack.

The amount of flies there are around your head means that some are statistically pretty likely to hit your eyes or mouth, they hit all over your head really, you're just a lot more likely to notice one in your eye or mouth.
posted by knapah at 1:16 PM on August 29, 2006

One summer at camp the gnats were very, very bad. One camper discovered that if he wound a towel very high on his head, the gnats would hang around up above his face and not bother his face so much. Weird.
posted by infinitewindow at 1:35 PM on August 29, 2006

You signify the potential for a juicy snack.

Hmm. I'm afraid I don't see why this is true. Some gnats bite people, but most of the ones I'm thinking of (in Wisonsin, for example) don't---at least as far as I can tell. I don't see how circling endlessly around my head is likely to help them get a snack (or even signify the potential of one). What kind of snack do I signify? Why?

[on preview: like infinitewindow, I've noticed that holding up a hand or a fern frond will make many of the gnats circle above one's head---I wonder if complicates the notion that carbon dioxide is the attractor?]
posted by washburn at 1:48 PM on August 29, 2006

Many species of gnats form a cloud which largely stays in the same place. If you see such a cloud, you'll notice that it is usually located above a prominent landmark, such as a patch of sunlight on otherwise shady ground, or an object on the ground, or whatever.
Move this landmark, and you'll notice that the cloud moves with it - the gnats use the landmark to keep themselves together, perhaps to allow for finding mates or something, I wouldn't know.

I suspect your body stands out from the background, making you a useful landmark, perhaps as you move through a cloud of gnats, or past a forming cloud of gnats.

Wear camoflage and lie down :-)
posted by -harlequin- at 1:52 PM on August 29, 2006

Perhaps they are eye gnats.
posted by chrisroberts at 2:21 PM on August 29, 2006

At biology grad school camp (for lack of a better term), they said to extend your arms over your head and wiggle your fingers to attract gnats away from your face. They had some reason for it (other than to make the n00bs look ridiculous).
posted by unknowncommand at 3:02 PM on August 29, 2006

Gnats will gather around the tallest person. Go stand next to your tall friends and let them nibble the gnats.
posted by desuetude at 3:28 PM on August 29, 2006 [1 favorite]