Thanks Redcap this is great information. Plus, the chickens are pre-seasoned ;-)
I think I will try a spray of 1% oregano oil on my roosts as well, to use as a preventative treatment for red mite and see how that works.
I make an essential oil emulsion with water for repeling deerflies (Chrysops sp.) using poysorbate20 (TWEEN20), and that works well. I have not seen any red mite, but I'll try it before they get hold.