Hi. This is my first posting to this forum. I have 14 chickens, different breeds about a little over a year old. About half of my girls have lost their back feathers (the rooster is now gone)and their backs are raw looking. I thought they would get better but now they have lost feathers on their thighs and around the vents. A friend suggested treating them for mites. Your forum info seemed consistant with this. I have treated them twice with Sevin dust, cleaned the coop thoroughly but they aren't getting better. Any advice on what this could be? Michelle