We have used em before and were thinking about getting em again. I cant say if it was the light summer we had when we used em or if they really worked that well but we have very few flies. The key to em is to put em where they will not get dug up by the goats and have enough shade so they dont cook. Thus the corners of shelters. But if there isnt enough manure in them to cover safely, id bring some in or pick a different area. This year the flyers are terrible just about everywhere in this area cause of the real light winter we had. The sucky thing about the fly predators is they dont breed and reproduce. So when they are gone... they are gone.