The whole year we've had our's, we didn't have mites or lice. When we intially put in the shavings and hay for the nest, I dusted them thoroughly with DE. Then a few months ago, we cleaned the flooring and bedding. I replaced the shavings and hay but forgot to dust with DE. Now I've noticed little tiny bugs on my arm and crawling up the wall near a mama and her babies. It was at night and I don't see them during the day or on the chickens, so it makes me think probably mites. Today, I dumped all the flooring and will be replacing it tomorrow with new hay (nice neighbor gave it to me) and some DE and poultry dust. Nests will get replaced too.
I don't want it to get out of hand but from what I've read they are extremely hard to get rid of. And I just hate using chemicals but everyone says DE alone will not get rid of them but will help deter them if you don't have them to begin with.