Thanks! I sprayed the coop/ nest boxes with a water, oil and dish soap solution which I read helps smother out the mites. I pulled out the floor of the coop and cleaned that really well and sprayed with the solution and then dusted everything in the coop, all the cracks and crevices really well with DE.
I wanted to try to get my hands on some permetherin because I've heard this works really well for treating mites, but I i'm in Canada and it is very very difficult to find anywhere, I don't think it is legal to sell it here and really hard to have it shipped from the states for some reason (could just be the current border situation?). So permethrin is unfortunately not an option!