One and a half year old BO has had this problem ongoing for 2 months visibly, everyone else looks fine. Her feathers are dull and in that bare patch there are feathers there, but they are chewed to the shaft. I have dusted with permethrin, then again 9 days later. Dusted with Sevin and again 10 days later. Cleaned (vacuumed out even) the coop and sprayed it down with Oxine (not sure if that was the best chemical to use). She is still shaking her head and getting chewed on. Enough! What is my best plan of attack? I'm ready for a topical application - I despise dusting them and they hate it too. Just Ivermectin Pour on? Or should I piggyback it with something like Advantage as well? Then again in 10 days, or two weeks? Help me, I feel like a chicken slum lord when anyone comes to visit, and of course she is the most outgoing, so there is no hiding her!