You can also use your finger nails to scrape the base of the feathers where the louse eggs have been deposited and while not pleasant, it is quite effective.I am battling lice now as well. I discovered them on my roo after he came back from the vet for an injury! Two vets didn't even notice! Ahh! That was over a month ago. I still am seeing eggs. Roo was pretty bad. I found them under his wings as well. It hasn't been warm enough to spray with Elector PSP, so I've been using the dust. I've already washed Mr. Roo and blow dried him....took forevvvvver! I will admit I went 2 1/2 weeks without re-dusting. I hope I can get all these little buggers. I have just been applying the dust directly under the vent and on back of the neck of the hens -did everybody's wings initially. Roo, I keep doing under his wings too. Should I just keep after them with the dust until weather warms up and I can douse them with Elector PSP?
The most important and rather brutal point to make is, the battle with mites and lice isn't over until they and their offspring are all dead. This means repeated examinations and repeated treatment.