I battled mites it seems like forever. I treated every 7 to 10 days with 7. I scrubbed every inch of the pens, I treated out side around the pens. I treated the chickens and I even hand picked any mites I saw on the girls. In 2 to 3 days, I would see mites again. I had such an infestation I even lost a Roo. Then I got to reading up on mites and figured I might have a rat/mouse issue, which are big carriers of mites. So my husband and I declared war, tore the barn apart. We emptied everything, cut out the bottom inside wood and found nests upon nests of rats! I tell you honestly that in 2 days we killed 88 rats of various ages. That was 3 weeks ago. We put out rat/mouse poison, in those little house things that you need a key to get into to change the poison. Since we did that, and I treated once again with 7 and killed about 30 more rats, then treated the girls twice with Ivermec, the mite issue is over. THANK GOD!!! I know we still have a few more rats and I will get them too, but I believe the Ivermec was one of the biggest helps of all. I keep my pens cleaned and only use sand for their floor. That helps with cleanup.
Hope this helps Good luck!