I have my FF and springtail cultures in my under-stairs closet on a shelf. I have mite paper on that shelf and nothing touches. Tonight I went to move things around a bit and found a rogue couple of flies outside the containers... not a good sign lol. So I started poking around more trying to figure out how the heck they got out (which I am baffled by honestly) and when I did I found a sort of powdery substance around the container for my springtails. It was like it was all around the edges in the rectangular shape on the fly paper. It wiped up like cocoa powder..... and upon inspection really closely it didn't appear to be moving (if it were mites or something) but maybe I just couldn't see. I have seen mites on my older fly culture lids (purchased) and was able to see them moving, and this didn't quite seem the same and I even tried to look with a magnifying glass but again didn't see any movement. I also looked verly closely at the lids of the FF cultures and didn't see anything on top like I did on the others.