I have kind of scratched the idea of breeding superworms, because the beetles stink (A LOT).
Although, I have read that a lot of people have a hard time getting these guys to pupate, but I don't seem to have that problem at all. Beetles keep popping up out of the substrate in my MHD's enclosure. I think if I wanted to actually breed these guys, I could just let 5-6 loose in the substrate and let them pupate and then put them all together.
I really don't know how exactly they are getting into the substrate, because I am 100% sure they cannot climb out of the feeder bowl. The only way they could be getting out is by climbing on Morgana when she is munching on some of them.