I was told to use 7-Dust; but you actually use the lesser concentrated 5-dust. Can get it at Feed & Seed store. You put it under their wings and on their tails about once a month. I've also seen some other sprays and things you could put in their water to help keep mites down. Check out First State Vet Supply's website. They have some of these secondary things I mentioned.
Well if they're a light brown color, they're lice. And i use Sevin dust(yes, spelled that way)--I get it at walmart in the lawn and garden section for under $5. I use a large rubbermaid bin to dust them in as it keeps some of the dust in and you don't waste so much. I place the bird in the bin, dust them over real good(try not to get in their eyes or face), dust under the wings and then repeat in a week. You'll want to do the whole flock as they spread real fast and this will protect the ones that may not have them yet from getting them. Good luck!
which Ivomec is it that you need for the back of their neck?
Ivomec Eprinex. It is actually used for cattle as a wormer, but works really well for poultry. For Large fowl you would use .5 cc's, for bantam's you would use .25 cc's. You just put it on the lower part of the neck. You can repeat every 6 months.