Could be any number of things, but guessing from the pics & previous posts, I’d bet heavily it’s gnat larvae enjoying a cannabis root buffet. Hopefully, the mosquito bits work, never tried them. I tried DE when I was infested & didn’t have much luck. Nematodes worked great for me & should reproduce in the soil for longer protection, but can be more costly if changing soils every run. However, if you can find a local garden store that has them they’re fairly cheap. It’s the overnight shipping that really adds up