haven't had much luck finding information about this. I recently started noticing mites on the adult soldier flies that hang around my bin. they look a lot like the phoretic mites that afflict honeybees, though I'm sure that's just because my vision isn't the best. some of the flies don't have any, some have just one or two, and a few seem to be just about covered with them.
this concerns me. the flies with a lot of these little parasites on them seem to really struggle. instead of flying around looking for a special friend, they spend all their time futilely trying to brush the mites off with their legs. even the flies that only have a couple seem a lot more lethargic than I'm used to. if these are something black soldier flies have adapted to, it seems likely that the BSF females will stop laying eggs in my bin, which would be terrible.
the one very brief reference I found to mites on soldier flies was a picture of one on a larva. I haven't noticed any on the larvae yet, but they're wiggly little nosers, so it's more difficult to check and I don't know for sure that there aren't also mites on the larvae.