small black bugs on my chickens

[1eggnog]

hi everyone, i have a range of chickens and not all of them seem to have this.
there are small, long, black bugs on them, not alot but they are still there. These bugs end up in my clothing and are a bit itchy so they must be uncomfortable for the chickens. i have dusted them with red mite powder although these are clearly not red mites. i think i have identified them as corn lice. are they a danger to my chickens? and how do i get rid of them?
thanks to anyone who can help me

 

[Lorilyn Farms]

I bathed my birds that had them with dog shampoo. Don't know if it's harmful, but those little suckers went down the drain...(The chickens get a blow dry afterward in the bathroom )

 

[Lorilyn Farms]

Also try your woodstove ash, diatomaceous earth in the coop.