Not to push the “off topic” of deer flies...but...
I found a solution to the little bastiges gnawing off chunks of flesh when I mow my grass (2+ hour job)
I use a grade stake a blue cup and some Tree Tanglefoot, which is a sticky insect barrier product.
Wire tie the grade stake to my tractor, staple the blue cup on top, and smear some Tanglefoot all over the cup. The deer flies are attracted to an object “moving through space” as in mowing or walking. They also are attracted to BLUE! Voila! The result...