My frugal husband came home with a gallon jug of this stuff called Dy-Fly. He got it on the cattle side of the feed store. Its for all livestock including horses. It smell really bad and your suppose to just do a light mist being sure its just on the outer hair not down to the skin so you know it has to be nasty stuff. It works
Our main problem lately has been mosquitoes and those big nasty horse flys.