I've read a lot on this site about a chicken's first molt, but our 4 birds are only 7 months old and should not be molting yet. 3 of our 4 have stopped laying completely (the first one stopped in October, the other 2 stopped in early November and mid November). We are still getting 1 egg per day from the 4th hen. The first chicken that stopped laying started to lose feathers on her head and neck around the same time. One of the other birds (the most submissive one) started to lose a couple of feathers on the top of her head near her comb. We feared mites or lice and examined all the birds but couldn't find anything. All of their combs are red and look healthy to me.
We treated their coop with a vinegar/water mixture and hosed it down thoroughly, and also sprayed the birds, and put ash from the fireplace in their dust bath areas a few times. We bought permethrin poultry dust but haven't used it because it seems very harsh. Now, all the feathers are growing back quickly. My question is: does this mean we have solved the problem? She hasn't lost any additional feathers. Also, do you think the fact that the 3 birds have stopped laying is due to decreased sun exposure? We would really like to avoid using the permethrin, but will if we need to.