Hello and welcome to frog forum! Crickets are WAY better than mealworms. The worms have a tough outer shell that is hard to digest. Crickets also move faster and are more likely to get their attention. Remember to always dust with calcium+vitamin d3 every other feeding and a multivitamin powder once a week. Other food options are dubia roaches, nightcrawlers cut to size, or depending on the frogs size, flightless fruit flies. Here is a sheet on their care and and in these initial stages its important to keep a close eye on them. A quarantine tank with damp unprinted paper towels as substrate and only the basic decor is recommended for the first 30 days. Anyway, heres that care sheet American Green Tree Frogs as Pets - Care & Feeding good luck!