Dubia roaches are the best, hands down. Small-medium nymphs would be appropriately sized. Dubbed the best feeder insect in the world, research them and you'll see why. The effort of starting a colony and paying the price might turn you off, but the reward is endless. Crickets are more commonly available, the price you can't beat and availability. Not a lot of nutritional value though unfortunately, but with occasional supplemented dustings and prior gut loading should give your toad/frog proper nutrition. Mealworms are the larvae of a beetle (Hence containing chitin), once they pupate they are very high in chitin making up their hard outer exoskeleton. Not a great protein-fat ratio either. I would try red wigglers or night crawlers, although maybe not since frogluver said they give her frog diarrhea. I would still try them out though. All frogs can handle some parasite loads, it's when they're stressed commonly in captivity is when it is deadly. Weakened immune system leads to illness, pre-mature death.