Just curious how do you know if your chicken has mites? Can you see them?
Most mite and lice species are quite visible. For the most part what we have around here are common poultry lice. These are reddish or whitish, oblong, and about the size of a flea. They crawl quite fast. They like to live in the feathers around the bird's vent and on the shoulders. They also lay their eggs - small, white clumps on the shaft of the feather - near the vent and on the chin of birds, especially bearded varieties. Sometimes you'll also see Northern fowl mites, though they aren't usually found in this area - these are pretty obvious, they are tiny (maybe 1/3 the size of a common louse) and they produce a dirty, oily black buildup in the feathers around the birds vent. I've seen a few cases of another mite as well - not entirely certain what it's called - but it looks similar to the poultry louse, except a bit smaller, lighter-colored, less quick moving, and it tends to hang out a ways down the feather, rather than right up against the skin.