Almost all of my hens have had bald bellies (just below their vents) and a couple have a little balding on the back and front of their necks, for a several weeks now. I have inspected them over and over and have never found any signs of mites or lice. I chalked it up to molting but I'm suspicious. Their combs are very nice, they're eating like crazy, laying very well, active, not listless, not scratching, have good weight, etc. So, I have been just monitoring closely for weeks. Well, this morning, I found one dead in the coop. She had good weight to her and looked pretty healthy to me, except for the same bald belly patch, like the others. Any ideas here? I have scoured all my resources online and not finding much help. I don't want to treat them for anything unnecessarily. Don't know what else to do. Thanks.