Pros and cons on seven dust
Sevin dust can cause cancer but many of us have used it over the years without a problem. I usually recommend permethrin nowadays, and you can find it in liquid concentrate form at TSC under brand names like Permectrin and other names. The lice treatment must be repeated every 10 days to get the eggs as they hatch, and it helps to replace the bedding in coops or nests, along with spraying the empty coop. You may want to look over these articles with pictures, and read about lice.