Shortly after moving one of my Camponotus fragilis colonies to a formicarium, I noticed all this microscopic debris looking almost like powder around one of the meal worm pieces laying in the out world. Upon closer inspection I saw they were mites, tens of thousands of them probably. I wasn't too worried about them, as they didn't seem to be parasitic or even phoretic, but they exploded in population within hours.
Under the microscope, I could see there were still more eggs EVERYWHERE. These mites were really funny looking too, having what looks like a long snout and hairs sticking out.
I have compost mites in almost all of my colonies, so seeing mites wondering around is nothing I'm not used to; I just have never seen these particular mites before. I eventually just moved the ants into another formicarium and washed the infested one out. I haven't seen anymore since.
Here's some pictures