Neem oil works (kills mites, and it stops common molds too as an added bonus), however don't spray within 2 weeks of harvest or it'll stick around and it'll taste horrible. You can get it at any decent gardening store. You'll want a good sprayer, preferably with a hose, and you'll need to mist all of the leaves of the plant. You'll want to hit the underside of the leaves too (that's where the bastards live).