I noticed one of my 4 chicken's butt was red. After further investigation, I saw hardened lumps on the feathers near her butt, next to the skin. One other chicken has this, and I saw a few small red tiny spidery looking things crawling around quickly. The lumps are circular around the quill (not sure if this is correct anatomical description) part next to the skin, about 1/4 inch in length-kind of white looking. It is very hard. Tried soaking in warm water bath per advise from friend, but after 5 minutes, didn't seem to loosen any. I have diatomaceous earth for worms/mites that I can apply. Any other advice?