Well if its Thrips you should see them crawling up onto your leaves and feeding so I don't know about it being thrips. Soil lice sounds viable....please clarify, are they only in the soil, or are they on the plants as well? Perhaps try this, even if it's not thrips, it should kill these things at larvae stage.....my man Hayduke put me onto this.....
Diatomaceous Earth. It is sold in garden stores as a crawling insect killer and in feed stores as a dietary supplement and de-wormer. It is the calcareous skeletons of ancient diatoms. Some of it is mined from marine sources and the organic OMRI CODEX human grade is mined from ancient lake beds in New Mexico. It is sometimes called Fossil Shell Flour also. The microscopic spiny skeletons make little cuts in the exoskeleton of insects and then dessicates them.
I have used the garden center in the garden, but I also now have the human grade for a wormer for the cat and dog during flea season as well as mineral supplement.
Thrips larval stage is in the soil, they pupate, crawl around in the soil for a bit, then looking for the goose that laid the golden egg , climb the bean...er pot stalk to rasp away on our chloroplasts.
I put the white powder in a salt shaker and apply to soil surface after a good watering, but also after the very top of the soil has dried a little. I have also read of making a paste with water and painting on the trunks of fruit trees (good white wash for fences also!) I am not sure if the paste would be ok for MJ plants or not. the top layer gets watered in and adds some calcium ad other minerals, I also do not fully know the ramifications of this though I suspect in moderation it is beneficial.
I only sprinkled the DE on the soil surface twice and with spinosad spray for the adults on top, they were gone quickly. The recurring problem happens when the larval stage escapes the spray, and the DE gets them good...and it is non-toxic...even people eat this stuff!