We rode yesterday near the creek. The deer flys were out in swarms. We had put fly spray on and some of the roll on bronco stuff on the ears and poll area. They were still "bugging" the girls.
I had a Bounce dryer sheet in my shirt pocket. I heard to do that to keep skeeters away. I tucked the dryer sheet under Vidas bridle right between her ears and surprise the flys stayed away, at least left her ears and head alone. She looked like she had a cute little white bow on her head too
Yes fly traps are great. Keep them in areas that don't get a ton of human traffic if you use the one that mix with water. They smell awful
Another tip is if you go with them get the disposable ones. Again the gross factor comes into play. When they are full of dead flys and maggots, its easier to just toss it than clean one out and add new stuff.
ETA
Get this kind, the bag ones you run the risk of it breaking open and going everywhere...yuck