You must use Spinosad as a root drench. That is the only way to get rid of them and it's crucial you add 1-2 drops of Dawn dishwashing liquid as a surfactant or you will not get rid of them. The oils and waxes on their bodies will form surface drops of air allowing enough of them to live.
It's 15cc/1 gallon water with 1-2 drops Dawn. Water with that every 3 days until they are gone. Usually takes 3-4 waterings. Then weekly root drench until you harvest.
If it's mites and I must have those genetics I clone the plant, isolate it and dip it in Avid and root drench with Avid (Avermectin). I won't flower a plant with mites and I won't allow it to stay anywhere in my indoor grow for concern about establishing a mite colony. Here is the MSDS on Avermectin:
https://www.caymanchem.com/msdss/17453m.pdf This is an issue in mammals because you can generalize the Glutamate channel to our Glycine channel hence the neurotoxicity.
If you use Avid you have to clone out for three generations without treatment before you can flower. I actually wear full chemical warfare gear when I work with Avid. Avid is a potent neurotoxin. I do not have mites in my garden for this very reason. If you get mites established it is almost impossible to completely get rid of them. I'm sure some here have had success.
I've been looking at Grandevo and Venerate from Marrone (
https://marronebioinnovations.com/), as I've been extremely happy with their Regalia product. But I have no direct experience.
As for Pyrethrins 1 PPM is considered enough of a contaminant in CA to consider unsafe and it's not approved for use here in Cannabis (
https://www.cdpr.ca.gov/docs/cannabis/can_use_pesticide.pdf.) Here's an interesting article on Pyrethrins:
https://www.projectcbd.org/cannabis-pesticide-regulations-need-rethink-pyrethrins-eagle-20. I personally do not use them because they did not work in veg for me.
Essentially you want to look at products safe to be used on Tobacco. I come from medicine so I'm far more conservative than most. Since I do not sell I am mostly researching and breeding for a specific trait; pain relief.
Good luck