I have a large flock of chickens, and one thing that plagues my gals (and roos) are mites (red) . It seems like nothing I do gets rid of them long term. What I mean is, I can dust and spray, and i've even used ivermectin, but just a few weeks later, the mites are back. So I re-treat. Again, and again and again... (not with the ivermectin, but with sevin, pesticide sprays, etc.) Some things about my place: Neighbors have about 150+ birds in henhouses all along the fenceline, they never treat for parasites. Could that be a source of ongoing infestation? I free range my birds in that side of the yard, also my pens are on that side, setback 10+ feet. I keep my pens clean and spray for pests every 2-3 months with a water-solution sprayer, usually a pyrethrin. When I put in new bedding, i dust it with sevin, and same with nest boxes. My henhouse interior is pressed plywood/particle. Its not painted. Should I paint it to reduce crevices? If I am saturating it with pyrethrin ever 2-3 months, could they still be surviving it in some crevices, or are they just bird to bird? Oh, I forgot to add that I do not have this problem with my birds that live in the front part of my acreage, on the farthest side away from the rest. Suggestions or ideas on how I might get a better control of this? Or why I am not being very sucessful?