I live in southern KY, and heat, poo, and humidity are quite a powerful combination to draw flies. I use the vanilla scented car fresheners (the tree shaped ones).As soon as our weather goes over 80 I hang one on each side of my open air coop/run combo. I swear no flies! Must be the trees, and must be the vanilla scented ones. Tried other vanilla scented fresheners, none of them worked. If we're having a bad year with bugs, I might put new ones up again in July or August but usually just once in late spring is enough to keep the flies away til cold weather sets in again.