A few years ago my hens, quail AND me got infested with poultry mites, apparently brought tino the henhouse by crows stealing eggs. They even got into my bed, leaving me at one point with hundreds of red VERY itchy bites. Who knows what hell the birds endured before I realized what had happened via Googling (they are VERY tiny and instinctively climb UP the legs of animals and people....thankfully, for some reason, they spared Sweety and my cats). But they were easy to wipe out and it is easy to prevent them ever since.
Back then I filled two kitty litter boxes with food grade diatomaceous earth (I'd bought a 50 lb. bag on-line for $22 as I recall) and put one in the henhouse and one in the quail pen. Once I realized they'd gotten in the house due to my bringing Mr. Rooster's sleeping cage into the laundry room at night I cleaned out the cage, then sprayed the inside with some permethrin I had dumpster dived, and put diatomaceous earth in his straw bedding. Ever since he now spends evenings in the garden shed!
But here is the biggy, which I did here 2 days ago......I put the hose end shower head sprinkler inside the henhouse as the girls roamed the yard and ran it full blast for 20 minutes as poultry mites want BONE DRY conditions, which they get during our annual spring drought. I did this with the quail pen too. Problem solved. I do this soaking each April now and have not seen (or felt!) a single poultry mite since.
Soaking the henhouse benefits both "Gracie's Grape" and "Gray Street Grape" not only by providing a deep watering, it also rinses all that accumulated chicken poop into their root zones.