a few of my pullets are having feather loss around their necks and a lot of scratching around that area i started sevin dusting them and their area. I did notice small slender grayish bugs in their coop and one was on my foot but i cannot find any bug on the chickens themselves. They seem very fragile to were just touching them seems to kill them. My question is lice or chicken mites and how to get rid of them.