Well here we go again. I thought my one hen was looking particularly scruffy (they have been molting), so I scooped her up for a better look and DANG she had egg casings stuck to several feathers around her vent. I dealt with this about 3-4 months ago. I used Sevin dust on all of them and repeated in 10 days. I clean out their coop as best I can (raw untreated plywood), removing bedding about once a week. I dust the floors and roosts with Sevin about once a month. My hens free range every day so am I just going to keep getting re-infested from wild birds or is there something more I can do? I have 16 hens so dusting them is a real chore. Any advice?