ustmd
Platinum Member
We have had good luck with Fly Predators and good manure management.
Horseflies and deerflies are different than manure flies or biting flies. Those in the horsefly family (Tabanidae) are visual hunters and impervious to scent-based controls. The fly predators also do not work on these (they don't breed in manure), nor do flysprays. They are awful here this time of year, especially for horses that are "high-contrast" colors.
I have heard many good things about the Epps Trap, but haven't purchased one yet. It's on my wishlist! (there are a few plans online for homemade traps of this nature)
For an inexpensive solution, check out this research from the University of Florida. We have made the blue sticky traps with success, and we mount them on on the tractor this time of year and hang them from trees. We are in New Hampshire. My father in Wyoming also has a tremendous number of deerflies on their ranch and swears by these traps, as well.
For the humans, you can buy deer fly patches for the back of your cap or shirt. These work because the deer/horseflies circle around looking for a place to land. Riders and fishermen often use them.
Here is a page with info about horse and deer fly behavoir and instructions on making a cloth or wood trap. My wife has made several of these and they really work well.
Deer Fly Traps she uses a black target for horse flies and a blue one for deer flies.