Culturing Drosophila sp. (more specifically I work with the species melanogaster) is pretty simple, I would say the only thing you have to worry about is contamination and mites.. but both are easy to get around if you do your reading. I buy premade dry media that you just add water to.. mostly because I'm too lazy to make my own.. but it's mostly just potato flakes and yeast. Then I add excelsior, the fibery material inside in these pics, to give them more surface area to pupate on and balance moisture.. you could use coffee filters even.. there are tons of methods.
Then you just add some flies from another culture and close it up.. since they can't fly they just look like ants moving around. They are like 3mm or so in length. A few days later you'll see small maggots in the media, which will pupate on the sides of the culture and the media, and hatch out in a few days. The culture lasts around a month or so, so I just make them every 2 weeks and it takes 10 minutes. 2-3 cultures could probably feed 10-20 frogs.. I only have 6 frogs but keep that many cultures as backup in case one crashes. But that is the 'downfall' of darts.. they require smaller food items which are not commercially available in local pet stores and you usually have to culture them yourself.. unless you go to a university and can use their flies, since melanogaster are commonly used in genetics research..
Fresh culture..
Two weeks later its producing well..
I like giving my animals variety.. so I also culture a few varieties of springtails (a type of soil arthropod that decompose dead leaves and are like 1-2mm in size).. but that's even easier than the flies..