Sounds like mites:Update - I just checked on them and they seem find, all on perches going to sleep. But I took the opertunity to closely look at the coop and the entire wooden frame is covered in the tiny bugs, tens of thousands of them!
any home remedy that can kill them? diluted bleach solution sprayed on and lock chickens out? i powdered the coop but would have thought it would have started to hurt them by now.. given 24 hours...
http://www.the-chicken-chick.com/2012/08/poultry-lice-and-mites-identification.html
-Kathy