I live outside Phoenix, AZ. When I moved here, I realized that flies only vacation elsewhere, they all live here in Arizona! I tried this product on a whim, it does truly seem to help the horses - it does not reply the flies, but the horses don't seem to get bitten like they did. I combined this with 1/4C of apple cider vinegar in their feed, and they seem more comfortable than in years' past. I recommend this project.