I tried everything mentioned thus far with NO luck when I found mites in my flock a coutlet years ago. What finally worked and completely ended my mite problem was Frontline Plus. I got the off brand at Costco and put a few drops on each hen and rooster. I was so freaked out that we had tried all kinds of toxic chemicals on the roosts, floors, nest boxes, the ground around the coop, our yard, house, and everything possible. It was crazy, but we got rid of them. The only thing that got them off the hens was the Frontline in each bird. I apply it ever 6 Mos or so to make sure I never get them again. So far we haven't and it's been 2 yrs.