Okay so I noticed that my polish pullets have lice in there beards and muffs. I've read that 5% Sevin dust is the best way to go as far as treating lice. Is this safe to use on their beard, muffs, and crest with it being so close to their eyes and mouth?
Just hand dust them as best as you can trying to keep it out of their eyes. It is very good for treatment of both lice and mites. Be sure to repeat treatment in 10 days for lice eggs, and the litter in the coop and nest boxes need to be cleaned out and disposed of or burned. Sometimes it is hard to tell which you are dealing with--lice or mites, and here is a link with pictures: http://anrcatalog.ucdavis.edu/pdf/8162.pdf
Have you already treated with Sevin dust? I'd recommend food grade diatomaceous earth (DE) over Sevin dust. Getting rid of lice is easy. Just add the DE to the place where your chickens like to dust bathe. A little goes a long way. Mix it in a little. Your chickens will dust bathe and take care of the lice themselves.