The horticultural products Elaine mentions will only result in resistant mites if one uses them preventatively in regularly schedules treatments. I always recommend against treating a plant for a problem it does not have. That is, as she points out, just dumping toxins on your plants or in your garden for no good reason.
However, horticultural acaricides (Forbid 4F, Avid [generic is abamectin, other brands using the same concentration of abamectin are Mynx2 and Timectin] and Floramite) are effective because they are absorbed into the plant surface, but they do not travel inside the plant. So they are more properly translaminar. Because they are absorbed, they do not remain on the surface where they might endanger beneficial insects. Mites suck it out of the leaf and die, and it remains in place for 6 weeks or longer. So the hatchlings will also be killed on their first feeding. Home remedies do not affect eggs unless one manages to the hatchlingsbefore they lay eggs themselves.
The main benefit in using products made for this purpose is that they are effective. There is no guessing, and they always eradicate the infestation with one spray. When I heard dreadful stories of people combatting them for weeks, months or years, it is no less than tragic that they have not heard of these certain solutions.
Buying a quart would be very expensive, but there are usually repackagers on eBay who will sell an ounce or two for around $15-20, and since only a few drops per quart are needed, I have had one ounce last me over two years.
