Question
Hi.  I live in both the US and Sri Lanka, and I have encountered these guys in both places (in the US during warms months).

They are flying insects, and appear no bigger than a pinhead or dot. They tend to hover right above your face, particularly if you've been sweating.  In fact they are so close that when you swat at them, you usually end up slapping yourself. When you do swat them away, they come right back.

One time I sat still, to see what one would do. It ended up landing just inside my nostril, so I assume that they are attracted by carbon dioxide.

I've never seen one still (except after smashing it) so I don't know what they look like, but flying they look like a black dot.

Any idea what they might be?  They seem pretty common, but I don't know a name for 'em.  They are, BTW, much smaller than your typical gnat.

Thanks.

B.

Answer
Bennett,

The smallest biting flies are the biting midges (Ceratopogonidae; see http://www.livingwithbugs.com/swe_itch.html for a description of a condition in horses caused by biting midges). Another smallish biting fly are black flies (see http://www.livingwithbugs.com/black_fly.html for a drawing of a black fly). You did not say if bites were a problem but if you are being bitten I'd guess it is one of these. There are many other non-biting flies but it would be impossible to determine without a specimen.

Jack DeAngelis
http://www.livingwithbugs.com (the 'Bugs website)