Lice and Mites

[GillerInstinct]

Six of my 7 chickens have lost their butt feathers. All are healthy and laying, but at this point I think the issue is lice and mites. I cleaned the coop spotless and sprayed a solution from tractor supply. I spray the coop with this product every night. Feather loss only happening on their butts. Any help is appreciated. Thanks.

 

[sourland]

Sounds like feather pecking/plucking to me. The two in perfect feather are most likely the ones responsible.