I clean out my coops about every five to six months and I treat for mites when I do. After all the shavings are removed and the nesting boxes are emptied out I treat the entire coop and the birds. I use Adams flea and tick spray for dogs and cats. It has pyrethrins and is a quick-acting, short-lived product. It is safe enough for kittens, so adult chickens are not harmed either. I pour the stuff into a pump sprayer and treat the nesting boxes and all the places where bugs can hide, such as where the walls meet the floors, any crevices, etc. Then all new bedding is placed. Last of all, that night when the birds are roosting and asleep, I do a quick spray of their backs.....they don't even notice. Here in Hawaii, parasites are a major problem because we have no winter freezes to knock down bug populations. This routine has worked really well for me, much better than using DE did. Plus, I don't irritate the birds by trying to individually dust them. Pyrethrin is a potent insecticide made from a type of chrysanthemum extract and it really works. You really don't want to tolerate mites for very long. They are annoying to the birds and in time can cause anemia.