If you raise the mealworms then you can pick which ones to feed them. When the worms molt they are a softer whitish color that can be fed to them and won't have all the shell. You can order them and feed them until they molt and feed the softer ones to them.
All of these sites have live food that can be ordered for newts, frogs and salamanders. It will take a litte more to culture them but it would be well worth it in the end. More healthy food results in healthier critters.
The flightless fruit flies, probably the hydeii would work although they are small. Forktreeranch has large flies, blue bottle flies that would be a more suitable fod source. The mealworms are easy to culture and grow by the hundreds if not thousands. Your frogs might even eat the beetles. Just make sure to the regular mealworms not Kings or superworms.
I am in the process of making links to the live food cultures I posted before, it will be in the stickies.