Do some research on Ivomec (Ivermectin). I did not have good results with it and I did read something on the internet that said in order to effective the dosage is almost lethal. Permethrins and Pyrethrins were of little help either, Internet says, and so does my personal experience that mites will develop a resistance to both.
I wrote on this fairly extensively on the ABC Forum so I ain't doing it again. Suffice it to say that after 3 years of battling mites, I haven't had a problem in over 7 months now. Not one bug anywhere. Prior to that, I'd get the beat back but never eliminated and within two weeks I'd have birds totally infested again. I actually lost a couple good birds to mites and it get REAL OLD having to treat a couple hundred birds every single weekend!
God Bless,
How did you get rid of them????