Anything you want its still early. Neem, horticultural oil, something that will kill eggs. You can do a rubbing alcohol and water mix 50/50 dont go over this ratio or you will get in the danger zone of damaging your plants, the rubbing alcohol will kill eggs. Probably dont wnat to do this every three days by itself. You'll want to do other foliar feedings in rotation. Test one plant first mmmkay.
Although just water will kill adults you should get into foliar feeding and foliar feed something every few days and not only will you kill the adults but you get the benefit from the foliar feeding.
If you do foliar feed keep the ppms low 250 - 350 wont be an issue what so ever.
Trick is, is to get 100% coverage. and spray every three days, dont be lazy about it. Couple of sprays and they should be about licked couple of weeks you shouldnt have any more mites.
Beercan mentioned dish soap/surfactant forgot that, helps to spread the water out, helps it stick.