Hello, I have noticed some of my chickens looking scruffy. They have missing feather and bald patches and look awful. However it is not all of them. They are about 4 years old and assorted breeds. I have Buff Orpington, Comets, Brahmas, etc., I had thought it might be mites so I dusted all of the birds and stripped down and dusted the coop and run and also put diatamaceous earth down. They look like they are moulting..but they are not. I am bot sure what to look for or if there is something else I should be doing. I also had one die s few days ago..and that one looked gorgeous! She was my favorite hen. :-( She was a Golden Laced Wyandotte and her feather were beautiful. I found her laying in the coop with her head tucked under her wing. I am at a loss. I have been asking other people in the area with chickens and they said it is their age..but I didn't think 4 years old was very old. They are being fed layer pellets and we also throw out black oil sunflower seeds and cracked corn for them to sctratch at. They are in a large coop and an enclosed run but are allowed to free range the pasture when we are home.