It could be my imagination but it seems like there are less of them overall. For sure when I use the disposable fly traps there are less flies overall. I can't stand seeing horses eyes covered in flies. If I were a horse that would drive me insane.

I think in addition - depending on where you live - controlling surface water would be a factor. Don't leave water to go stale in puddles or containers, and if you have something like a pond, either treat the water with something or get plenty of mosquito-egg-eating fish.