You definitely need to get some red mite spray / powder. They have it in all the Ag stores - your choice to go with chemical or organic, but even though I am an organic farmer, the chicken house gets washed down with a chemical red mite wash as it seems the only way to get on top of the mites.
I did buy a smoke bomb last autumn - you light it in the house (no chooks obviously!) and it smokes all the beasties out -