I have been using Topper's Bug Buster fly spray for about 2 years, I believe. At first I was skeptical, but after testing the ones with tons of chemicals and watching my horse run away from me and then using this one and my horse actually enjoying it, I was sold. Of course, I was also watching to see if it was effective with the flies and it 100% works. I also use it to spray the barn down to keep the flies out and it’s super effective that way too. I love stocking up on this product!