Since they can be dissuaded from feasting when there is a brisk wind, I spend a lot of time wishing for breezy days this time of year. People wear netting over their faces and torsos, douse themselves in insect repellent sprays, and spend a lot of time waving their hands in front of their faces. If you have never experienced them, you may think this is a much ado about nothing, but trust me, the wee things can drive you mad.
There are stories of moose in the deep woods being driven crazy by the flies, and they can even prove to be fatal if the animal begins the season in poor condition. Though each fly takes just one drop of blood, the sheer numbers of them are enough to cause major blood loss.
We saw this moose in May several years ago. She and her two calves were dining by the side of the road up near Greenville somewhere. Clouds of flies were harassing them. I dearly wished I could share some bug spray.
It was pretty clear how she felt about the pesky things!