That's how I found that I had them too. I just treated them last night with seven. Wasn't sure if I wanted to use something so harsh but now 2 hens are missing feathers. One on her neck and the other on her butt. I watched on you tube how to, but wasn't as easy as it looked. I used a pillow case with a lot of powder in it, pulled it high on her neck, and fluffed the bottom of the bag all around her. then I pulled her out and tipped her upside down gently to make sure I got it in her wings (crease) good. I'm sure that I'm mite free too. Be sure to wear a mask and gloves. My hands kind of ached all night. Not sure if that was why. tonight I attack the coop. I had been working on it for a week. (I used deep litter method too with pine flakes) Good luck. I'm already crying, knowing that I have to do it again in 10 days.
(I have a thought. Bowlers use this bag of rosin to dust their fingers so the ball doesn't slip. I think I'm going to try something like that. The fabric will have to be a loose weave but will try to dust them and rub into the feathers gently.) I really was a mess.
I want to add since I see a post about frontline, that 6 weeks ago I tried the frontline plus. Maybe I didn't use enough but obviously it didn't work. would love to use it instead of the dust. I live in the Fingerlakes region of NY and fleas, mites, ticks are horrible. Using Frontline Plus and Comfortis (vet pill) together to try to combat the fleas and ticks on my dogs.