The house fly's have been very bad this year.....driving me nuts.......those flys offshore bury there eggs and spawn out of whale poop.....that's why they are the worst when you are on the whale(tuna) grounds...........
Sounds like deer flies to me. Don't wear dark colors or blue.
They should start to go away after the August full moon.
There so thick down Monomy that they can cary a small child away