In the past I have been able to control mites long enough to set up a new colony by not feeding them for a day or so then putting a potato in for awhile then pulling the potato out and placing it in a bag and removing any mealworms then discarding the bag. Use those mealworms as food. Keep the old colony far away from the new one and don't move worms from one to the other.This only works in the beginning, if the mites are really bad(horror movie image) its easier to just start over, and buy mealworms till the new colony is up and running.