Hi, I am treating my flock for lice as I noticed some on my rooster and two hens (out of 11 chix) plus lice eggs on the feathers near the vent and lower belly, and redness and lost feathers in that area. I tried DE first, but it didn't work. I am now using a poultry dust with Permetherin (no Sevin). My question(s): I dusted on day 1 (active lice, eggs) and day 6 (supposed to be day 7-10, calendar error, eggs only). How long does the dust last on the chicken? Should I only follow up with those chickens who have eggs? How many more times do I need to repeat this? Thanks!