Yep, they are an actual thing, and not a very nice thing to boot. They are tiny little biting flies, so small that you don't usually see that they are swarming around you. I got bit by a bunch of them a couple of weeks ago and it took a week and a half for the burning and itching to go away.
The trick is to not itch them. That just seems to activate the poison or whatever they leave in you.
