they come when you visit,
they come when you work,
they come for dinner with a knife and fork.
Black flies are a tiny little pest with a big bite. They lay their eggs in cool, rushing water. They hatch in the spring. Then the little carnivores try to eat you alive!
Unlike mosquitoes, they don't pierce your skin and suck your blood, they take it by the chunk. They come in swarms, so swatting them has very little effect. And once they're done, the welts they leave behind make you want to scrape the rest of your skin off to stop the itching!
Lots of scientific info here.
We do wear bug hats, to help keep them off our faces, out of our eyes and ears, but some of the black flies are small enough to go through the mesh. Then you have them trapped in there with you, so you squeeze the mesh and squish them in it. By the end of the day it's hard to see through the blood and guts. I wear rubber boots to keep my ankles covered. Long pants and long sleeved shirts, no matter how hot it gets. We buy calamine lotion in bulk.
The black fly season usually lasts a couple of weeks to a month. That's when they're the worst. Cool, rainy weather prolongs it, and can bring them back in hordes just when you think it's almost over.
Here's a little video of a couple guys in the woods being swarmed by black flies.
But Wade Hemsworth said it best, with The Black Fly Song.
(The Little Abitibi is about 2 hours north east of us).