If you want a really good fly spray, get online and find a Piranha distributor. It works, but it's not cheap. A gallon of Pirahna runs about 45.00 from our distributor. It's such a nice feeling to spray the horse and see the flies hovering, but not landing. And spraying the flies sitting on the stall bars and walls and watching them drop almost instantaneously is, in my opinion, priceless!