I had a thrip issue last year and had some DM in the cupboard. I even bought a few empty powder sprayer things to puff it on the leaves more directly. (not very efficiently though)
I'm not sure it's supposed to be wet. I may be wrong, but it works by scraping the belly of the bugs as they travel over it. They then crawl off and die. Mildly sadistic unless you're talking about something that is hurting our girls!!! I also used to pull the wings off of those huge horseflies that would take chunks out of my horses-don't judge me
Try sprinkle it daily wherever you think the bugs will travel. I don't believe there's much harm to the soil other than the gooeyness that someone else mentioned once it gets wet.
Good luck getting rid of those! I'm back up and growing again after a total clean down from thrips & a mite or two. Grow and learn!!! I will NEVER bring anything from outside into my garden again.
Being without the plants was hard on my mental health! We're firing on all botanical cylinders now though!