People put Sevin dust and spray on their garden but I would read the package to see if it would kill the worms (and other creepies) that you want in your compost.
I found this thread while looking up the same issue. Except I have 5 hens and this is only happening with one of them. The under side of her belly is bare. The skin is pretty and pink with no sign of inflammation or irritation. My hens are about 8 months old and lay everyday without fail the...