I saw a new kind of fly trap at Tractor Supply I am going to try out. Going to buy a couple to hang in the barn at my sister's farm since she's keeping my horse for me now. I'll let you know if they work!
I tried those and they didn't work for me.Vanilla "tree" car fresheners....they really do work! Up where I used to live, twice a year there is a HUGE fly hatch with hundreds of flies invading homes, cars, coops, barns, etc. The vanilla trees really ward them off from out of the car, homes, porches, and coops. Don't know why, but they hate them.