Well, you certainly got me to look! Of course, I'm the mean Chicken Mom that MAKES her chickens take dust baths.
Sand (the sandbox cleaned kind) and DE are the main ingredients. I've been adding "land plaster" (calcium) to keep down the dustiness of the DE. The kids catch the birds and I rub them in it. The leftovers are sprinkled inside the hen house and nest boxes and the last bit is tossed into the dustbathing PIT my little monsters have dug. Walking around my chicken run in the dark is hazardous to my ankles and my spine. I think they move the pit three inches everyday.
Mine are all moulting also. The 14 to 16 month old crowd is doing their first official moult and the June Babies are losing the last baby feathers and getting their "true" adult plummage. Feathers are four inches deep the whole way around my run. Visitors want to know who killed what, lol.
Permectrin. Got it. We dip soon ("evil laughter"). Thanks for the laughs and take care.