Nope. No mold trouble at all. I have a few pics to post later some of my meal worms and a few of the super worm's new drawer unit and the one beetle I have at this point. I have a ton of babies it seems. They're all way to small to really tell, but under every slice of potato in the drawer there's probably 20 that are just laying there on the surface, probably 12 slices..... If thats what's in one thin layer of the substrate im sure there are several hundred at least in there.