Permethrin spray or the garden dust are pretty easily found at feed stores and TSC. For lice use them once every 10 days to get the eggs as they hatch, until they are gone. Empty the bedding from the coop and spray the coop nests, and roosts, and replace bedding. They can be a challenge to get...
Look her over for signs of lice, mites, or their eggs. Overcrowding, a diet too low in protein, or boredom can cause feather picking. Make sure they are receiving a 16 or 20% protein feed, either layer or an all flock feed. Let them out to free range daily. If there is feather loss previously...