I use permethrin. It has worked great for me. I get mine at TSC. You must thoroughly spray your coop, everywhere, every crack and crevice. I also use the permethrin poultry dust in the nest boxes. I had a severe infestation and the permethrin did the trick. It does not kill the mite eggs so repeat weekly treatments is needed. I spray for 3 or 4 weekly treatments and no more mites. The bonus is there is no egg withdrawal period.
http://entnemdept.ufl.edu/creatures/livestock/poultry/chicken_mite.htm
https://www.dummies.com/home-garden...-get-rid-of-your-chickens-external-parasites/
http://entnemdept.ufl.edu/creatures/livestock/poultry/chicken_mite.htm
https://www.dummies.com/home-garden...-get-rid-of-your-chickens-external-parasites/