I have a hen pinning and pulling feathers, but only picks on one (possible two) other hen(s). I've only caught her pinning one hen (my smallest), but the second possible target had pin feathers growing in, so I don't know if she was pecked or molted. The smallest hen has neck feathers missing, and is generally looking "rough," like some shoulder feathers are missing, and little down feathers sticking out here and there on her body. My daughter had been handling chicken chores for most of January and December, so I don't know if I missed a molt, or if I've got a mite/lice problem that wasn't obvious enough to grab her attention. I didn't think to tell her to check for signs of either. We had straw in the coop both months, and it was crazy wet here during that time, too. The flock is about 9 months old, by the way--8 dual purpose breeds (Barred Rocks, NH Reds, and a Buff Orpington). I've checked the picked-on hen a couple times and can't see anything that's obviously a problem. The second time there were some dandruff-type flakes on her, but not loads. So is grabbing some wood ash and sand and installing a dust bath in their coop a decent enough measure for now? Or should I just go ahead and grab some "icide" and treat, "just in case"? I've upped their protein, just in case it's a protein issue. And I isolated the aggressor a couple of times, which seems to have lessened, but not fixed, the problem.