i played with spider mites for almost a year. Did organic, blah blah blah. I finally tossed the most infested plants into the fire pit, trimmed everything back, and bought some
Avid. I mixed it triple strength, sprayed twice and haven't seen a spider mite since.
Note; do not spray on flowering plants. I only sprayed my moms and a few plants in veg. I burned flowering plants that were infested. Mites will not feed on a plant that has been sprayed. So I got to the point where I only was spraying my mother plants if i saw a mite or two. after about a month, the mites were gone.
be mindful this stuff is a neuro toxin. At the strength i mixed it, it would make my arms tingle. Wear gloves, long sleeves, eye protection and a mask. BUT, that being siad, the shit works and it works very very well on spider mites