I have a 2 year old black australorp who's been through the normal molting cycle in the past. About 2 months ago I thought she was molting so didn't think much of it until I realized that her entire butt was bare, completely featherless. I kept an eye to make sure pin feathers started to return but they didn't, instead she continues to look scruffier by the day and I noticed that she's starting to loose feathers on her neck and chest. This week I noticed that 2 more chickens now have bare butts. I've done some reading here and will head down to the barn shortly to check close up for signs of mites or lice but does this sound like I might have the starts of an infestation? I'm about to head for the feed store and want to pick up whatever I need including sevin dust & ivermectin.