Most insecticides that are not dedicated "miticides" only "control" spidermites, they don't eliminate them.

There is a miticide available to the home gardener, its called KELTHANE. It does work, I use it, BUT....it doesn't eradicate mites like you would think it should. They will pop back out if you aren't looking, usually somewhere else on some other plant than the one you treated.

I use a double-pronged technique in my greenhouse that seems to work well (and I have well over 75 plants, LOL, more like over 1500 plants).

I spray infestations with Kelthane, ONCE, when I first notice them, and I spray not just the infested plant, but everything within a 2 ft radius. This is for quick knockdown.

Then, a day or 2 later, I re-spray that same area and a little further out (maybe a 3-4 ft radius) with Neem Oil.

This works very well for me personally.

The only way to really eradicate mites, I have been told by others, is to invest in the predator mites, but that's more involved and expensive