Dumb question #2: one of my three chickens was missing feathers on her back, by her tail feathers. About the size of a fifty cent piece. Just bare skin it looks like with a couple of black dots. I see her preening that area, if that is the right term. I noticed other chickens inthe farmer's coop had that as well but bigger. Is this a concern, like could that be mites or lice or something? Should I expect that they will grow back? Des anyone have a picture of what mites or lice look like on a chicken? I have been reading and it sounds like I should pick up some 1% DE, whatever that is and some cedar shavings. The DE goes in t heir sandbox and the bottom of the nestbox?