I just went throught this in my room a few weeks ago. I was using a few types of bran and oatmeal as the substrate. I didn't even realize I had a mite infestation until it was too late, and there were billions of them all ofer the corner of the room.
If it's what I'm thinking its a grain mite. They love humidity. Did your substrate get damp at all?
To get them out of the room I just kept cleaning and scrubbing. Theyre actually harmless, but it's a major pain to eradicate them. I took everything out of the room and washed and disinfected what I could without causing harm to anything. One of the things I used that actually became a huge help were sticky traps. I got them at Walmart and there were I think 4 to a box. one side is all sticky, and the other has a sticky strip to attach to the floor and/or wall. Fortunately I have hardwood floors and it made it easer. I created a perimeter all the way around the affected area, and although its nearly impossible to stop them from spreading, I caught an enormous amount on the strips. Eventually the mites either died off or were killed because I dont have any more at all. I also ended up throwing out the entire superworm setup.
As a side note, I now keep the supers in a slightly smaller container and that now sits on an upside down flowerpot in a longer and wider rubbermaid container that has an inch or two of water. That keeps any mites that appear from spreading.
Hope it helps. Good luck.