Periwinkle is over 11 years old. She was fine until about a week ago, when she didn't seem to want to leave the coop, and when she would, she didn't want to come back in. One day I saw another hen attack her, so I decided to keep her in a dog crate so I could make sure she ate and pooped. Well, she's not pooping.......but it's probably because she's not eating or drinking much. I think she's really dehydrated. I've been giving her some diluted tart cherry juice and she seems to like it. I wasn't terribly aggressive with hydrating her, because I thought she was dying from something terminal...or just old age. Tonight, she got so weak, I thought it was the end. She is very thin but nothing is swollen. I held her for a long time tonight, saying my goodbyes to her. When I left the coop, I looked down and there were black dots all over my light-colored tee shirt. Dang. She has mites. I had scanned for lice (which one of my hens had a few years ago), and I didn't see any of those. She looks healthy, feather-wise. But I'm wondering.........can mites actually cause a hen to die? (even when you can't find that much damage on the bird from them? Maybe she has them, because some other illness (liver? ovarian cancer, etc.) has lowered her immunity? Anyhow.......I took her outside and dusted her with DE. I had put some DE in her cage, before the bedding, but I put more in there tonight. Is it possible that she is so weak just from the mites? I hope that's what it is. How long will the DE take to kill the mites? Thanks for your help.