You can feed them flies. I have a Grey Tree Frog and I feed him any fly I find in my window(he was an egg in my backyard so if I didn't rescue him from my pool he would eat whatever is in my yard, so its fine if I feed him flies from my window). Fruit Fly, Horse Fly, Deer Fly, House Fly, etc. He is a little bit bigger than a US dollar coin, so I say you can feed your frog whatever. You could use them as a treat because you would have to feed it a lot of fruit flies.