I feel that tube culture will not generate the amount of flies you think it will. berksmike is right, you are better off culturing your own or if you really don't want to do that get the jar of flies from your pet store. Or you can order some on-line. I'm not sure what type of feeder your frog is but my darts usually are all over them within a few minutes of putting the flies in. Otherwise the flies might tend to wonder off in the viv and find hiding places.