Look under leaves they are not hard to spot, block dots that move. Mist top colas and look for webs. If you have them...
Mighty wash by NPK industries, and a spray bottle. Douse the shit out of all parts of the plants at lights off (otherwise you could burn the crap out of your plants) , Apply twice to everything the first week, then periodically spray. Should keep them away.
I smoked bud with dead mites in it, I'm sure many bags floating around have all kinds of shit in them.