Pyrethrin-based insecticides are rarely effective in SoCal. Fifteen years ago they were overused and the mites developed a tolerance. I'd only use it in conjunction with other insecticides like neem, rosemary, cottonseed, or garlic oil. Don't give the little bastards time to adapt before a new poison enters the environment.
Scrub your grow space after this one is done and carefully inspect any clones before entry. Don't let in animals, friends, or yourself without first being clean. Nothing worse can attack a garden then mites.