Fruit flies will be too small for the frogs. Mealworms are a no-no because they are not very nutritional and their shell is hard and the frogs are not able to digest it. Waxworms are very fatty and have no nutritional value. Nightcrawlers are very nutritional and would be a great staple food but tend to be very big. They can be cut to about 1" pieces and tong fed to the frogs. Silkworms are also a great feeder but will have to be ordered online. Crickets, even though they smell, should be part of the diet. They should be gut-loaded. You can use orange slices, carrot slices, potato slices, romaine lettuce, apple slices, etc. The healthier your feeders, the healthier your toads will be! Isopods, like roly polys are also good. You can feed hornworms and butterworms as treats sparingly.