This hits close to home as I've become allergic to deer/horsefly bites - and my property is swarmed with them during late spring and early summer. I live by the Chesapeake and our entire area gets swarmed. Head over to the Delaware bay and the greenheads take over - think deer flies on speed, typically in 10x the numbers.

I have 3 acres of grass to mow and I get swarmed by the deer flies - badly. I have to essentially wear a bee keepers uniform while mowing.

I stay off the single track/out of the woods this time of the year. They typically don't get me on my road bike.

Bug sprays do not work.

Blue solo cups covered in tanglefoot will catch many of them. They like blue. But most make it to my hands/head.

I will put blue construction paper covered in tanglefoot on the towing mirrors of my truck and drive around the yard- I can catch 100's of them. I also hang giant blue balls in the back yard covered in tanglefoot - catch 100s and 100's of them. Doesn't seem to make a dent in the population.