I have a flock of pullets all about 5 months old. Some of them were missing feathers when I bought them at 3 months old. Eventually, I figured out they had depluming mite and went through every cure and lotion I could trying to cure them. Now, all of them are fine and growing in feathers without plucking them out, except for one. This is thanks to repeated treatments of ivermectin pour-on. The sick pullet is a Russian Orloff. She seems healthy and active except she is underweight and pulls out her feathers if I do not continue to give her ivermectin pour-on weekly (I was aiming for every 10 days, but if I wait that long she starts to pull again). Some of the other chickens who are now cured are still underweight with pointy keels, but I hope with time they will get a little fatter. Does anyone have advice on what to do? I have tried antifungal creams and oils, pymethrin shampoos, DE, no-peck lotions, high-protein feed, and even wrapping her up in bandages to keep her from pecking. I would much prefer to cure her rather than just cover up the symptom. Given time she will pluck out almost every feather she can reach. Depluming mites are too small to see and burrow under chicken's skin, causing them to itch and pull out their own feathers. They live only on the bird. Culling is not an option for me. Thank you for your help.