Hi there wconstantine , I personally use a louse powder or best described as a tick and mite powder. Being from Eastern Canada the brand names are different but as a rule ticks and mites like the corners and dark places so I sprinkle this powder in the corners of each nesting box and some on the bottom as well. Then around my coops I sprinkle in all the corners and darkened spots where they can hide out and multiply.
I will even put powder in the dust bathing areas at least once a week and lat the birds roll in it while dust bathing and it seems to work quite well. They are a bugger to get rid of but persistence pays off in the long run. It must be working good and I never come out of the coops with the vermin crawling on my arms so I consider that a good sign... Good luck and see if your supplier or members here at the BYC for suggested powders or sprays. Steve