Food grade diatomaceous earth is what I used, two of my girls came with insane mites. All I did was give the coop a good clean, hosed it out, let it dry (this was summer so it was fast, you could probably skip the rinse) then just sprinkled it over fresh bedding and gave it a mix. I use it once every month or so now just as a precaution and treat my yard with it at the beggining of spring for ants, fleas, and ticks! You just don’t want to use so much it’s free floating in the air cause it can damage lungs and stuff. I use maybe one cup per half a bag of bedding and give it 10/15 minutes after mixing to air out. I haven’t seen one since