putting cover over medium like sand, I use hydracorn, keep the bugs from getting into medium, DE helps too, can sprinkle on soil but messes with ph a little. 2 inches will do it.
just found few threads that are kinda the same.. pyrethrin drench then... well.. sadness... I hope i'll be able to survive them and make some cuts... i took some clones just before it, still in the ez-cloner but I didn't get great success with it so far...