with my flies, I either use ready made culture mix, or, simply banana on its own. About 10 days ago, I put a cup outside with just some banana in, and that was it. I didnt put a lid or anything on, as as I said, they were outside. Took it in yesterday, and it is absolutley teaming with maggots, of which half of them have pupated. And when feeding, I never keep small nymphs serparately, unti. they are old enough to feed on crix or roaches. So, I bung em all in a net cage, and put the whole culture in, until all the flies have been eaten. By that time, the maggots or pupae that were in the cup would have pretty much hatched out, so its almost a contsant cycle.
Cheers,
Ian