Those sound like horse flies and deer flies on steroids!
Yeah, not very nice!
Similar to the infamous FDFs I presume?
Just run a bit faster and they won't be able to bother you.
They don’t bite as far as I know, but they aim for your eyes and crawl under your clothes and in your hair (maybe a preference for dark hair?). And the worst is when you get in bed after showering and somehow still find one on you.
FDF as far as I understand is a term introduced by PG (?) several years ago.
DF would be deer flies while the F is just the normal expletive for something bad (f-ing).
Extensive research and experimenting has been done on the use of blue hats and sticky tape to lessen the unpleasantness.