I've had our hens for maybe four weeks now. One had a bald spot on her back when we got her, but we were told that this is probably from roosters. However, in four weeks there is no regrowth on her bald spot - and we have no roosters. Yesterday morning I noticed all four hens sort of "scratching" themselves with their beaks. They were fluffing up their feathers and picking at themselves (not pecking - it was more like a dog chewing at a flea). Today I went to refill their food, and when I picked up the feeder, I noticed very small, reddish-brown bugs crawling all over the bottom of the feeder. I imagine these must be mites. What do I do now? The hens are not free range, and live in a run connected to a coop. About once a week I dust the run with DE, and some DE is mixed in with the sand that I keep in the nesting boxes and on the floor of the coop. What do I need to do to get rid of the mites?