For whites and cuban treefrogs I would use a larger cage like a 20 gallon extra-high aquarium. The whites will also need a higher tempeture. Luckely green treefrogs are not the pickiest eaters. Feed yours about 2 or 3 small to medium sized crickets every other day or so per frog. If you wait four days to feed them double the amount you would have usually fed them.
Mealworms are another source of food for tree frogs.
If you use mealworms I suggest you put a dish in the terrarium to put the mealworms in so they don't just burrow away. With eaither of the two food sources mentoined abouve I would dust the food every other feeding or so. Following this care your frog should have a long livesd life.