I recently discovered that the chickens had mites...(itch itch). One of the broody hens had them on her, and then I checked the other chickens and found a few more. I looked all around the roosts and the nest boxes and couldn't find any of the mites but they were on the eggs! So I was very worried and lost some sleep over it before I decided to get the poultry powder for mites. This powder is a Permethrin product. I was going to get the Sevin dust but this was recommended by the clerk. So I burned all the bedding of the nest boxes and then I made a watery paste out of the powder and water. I used a sponge paint brush to paint the roosts (we have a very large open coop, like a shed). I completely covered them on every side. Then I painted the nest boxes with the mix. They dried and now have a white wash look. I put the chickens in a plastic feed sack with the powder and tried my best not to get it on their heads....didn't work very well. I think I got a lot of it too, but I'm still alive so I guess its not too toxic. Anyway I did all 14 chickens and then left them alone for the night. Today when I checked on the girls they all looked good except for one. This poor girl was sitting by herself on a roost and by closer inspection I noticed she was covered on the surface of her feathers with mites! It was really gross, and very sad for her. So I dusted her again, very thoroughly. SO MY QUESTION is, how long does this permethrin powder need to work? Last I checked on her she was still crawling with these mites. They are not crawling off her onto the roost they are just on her surface feathers. And she seems to be the only one. ANYONE?