Before beginning to spend the warm weather months in Meredith, we summered at our home in CT. We have a beautiful piece of land there that overlooks a cove off the CT river. Unfortunately, we are surrounded by water, woods and marshland - optimal breeding grounds for deer flies which are the scourge of the insect world. Heck...they are the scourge of the entire animal world IMO. From mid-June till mid-July they are really bad and for many years just made it miserable to do anything outside away from the immediate house.
I went into research mode.
I learned about how they are attracted to blue (so I didn't wear blue) and learned that they almost always are looking to land on your head (so I wore a hat). I tried to do stuff outside when it was cooler, less humid - and sunnier (helped a little). But it was still miserable as the flies would still come, eventually land and find a place to draw blood. And these suckers know how to bite. They are also stealthy (you often can't feel them when they land). It was hard to look forward to being outdoors.
Back to the internet.
I found these TredNot deer fly patches (link below), ordered them and tried them. I swear, they are a life saver. They are cheap, clean/easy to use and EFFECTIVE. Basically, you stick them to your cap and go about your business. When a deer fly lands on your head they are stuck forever. Remove the patches and replace after a few days. I put two on my baseball cap - one on top and the other on the back. One fly after another lands there in peak season and my record was 36 after a 2 hour yard work foray. It's actually quite self-satisfying. The one disadvantage is you have to accept that people may wonder why you're wearing a hat with a bunch of stuck flies on it. It's not a winning formula for impressing the gal next door...but I swear it works and it changed my outdoor enjoyment of that 4 week period in the summer.
I have a few of these patches with me here in NH but where we are there really aren't any deer flies. Still...I'll bring them along during an early summer hike or blueberry picking foray. If deer flies are a problem where you live, try these - they work.
https://www.amazon.com/40-PK-Deerfly...2RRWYTAVHA3P6E