I noticed that a couple of my free range hens had lice eggs on their feathers during a routine inspection... Ick. I don't know how they got them, but I went ahead and immediately dusted the whole flock with Sevin. I was VERY GENEROUS in how I dusted and used plenty, and there was a lot in the coop itself too. 10 days after that, I dusted thoroughly again, and thought that was that. Several days after that, I noticed one of my hens looked a little bedraggled. Her feathers were breaking on her saddle area, and when I looked more closely her skin looks awful. Her skin is covered with a flakey yellowish crust on the saddle area, and that's where her feathers seem to be breaking, leaving small "stubs" of shaft behind. I also found an adult louse clambering around on my shirt after checking the coop one morning, and saw a few grayish eggs clustered at the base of the same hens's feathers near her vent area. I didn't see any adult lice on her at the time, but I guess where there are eggs, there's more! I thought the Sevin dust would clear the lice up, but it seems that I have some survivors! Anyway, I was going through worming them this week. It's been 10 days since I put Wazine 17 in their waterer and I was already planning on using Ivermectin tonight on them. My question is, will this kill the remaining lice? There seems to be disagreement on this forum between whether these lice are blood-sucking or not, and if not I'm assuming Ivermectin will not help. Is this right? Is there another treatment I can do to kill them off for good? Or did I do something wrong? Thank you for reading!