You could do a triple threat treatment. First remove the birds and any non-metal thing from the run. That means all wood, straw, shavings, paper, wooden perches, manure, feed... ANYTHING that is not metal or dirt. Then spray down the pen with the insecticide of your choice. DE is not an insecticide in my book. It is a 'deterrent' of the weakest sort. After you have sprayed the entire inside of your coop, the outside of your coop, the wire, walls, ceiling and floor, treat every wooden thing you own. Spray it all over with permethrin based insecticide. Then dust them with poultry and garden dust. Put them back in the coop. After you fill the nestbox with bedding, sprinkle it liberally with poultry dust. Bleach the waterers and re-fill. Empty all the feed, or let them eat it down and then spray the feeders with the permethrin spray, dust it with poultry dust. Refill the feeders. Last of all, treat your birds THOROUGHLY with whatever you use to control mites. Some people swear by Adams Flea and Tick Spray, Frontline, Pour-on Ivermectin, in addition to Liberally dusting them with poultry dust, under wings, belly, back, nape of neck and especially around the vent. Treat them every three days with the poultry dust for two or three cycles. You should see zero mites at that time. If you see mites again in a few weeks after all of that, you have a re-infestation problem, possibly wild birds, mite infested bedding or wooden perches, rodents, or possibly being carried back in there by you yourself. Yes, you could have a few stray mites on your shoes or clothing after the big cleanup and could possibly re-infect your own flock. Wouldn't THAT be a bummer! Wear stuff you can just toss afterward so as to break the chain. I read somewhere that those nest mites can live up to 36 weeks with no meals, so you are not going to be able to outlast them if you just try to starve them for a few weeks. They go dormant and pop back up to life when they feel a living warm thing nearby and schlep right over there and start their cycle again. Not trying to be a total downer here, just trying to let you know what you are up against. Good luck! Post pics of your dusty birds and clean coop!