From what I have read for leopard frogs ..."The diet consists primarily of insects - beetles, ants, flies, and leafhoppers. Other invertebrate prey includes pillbugs, worms, snails and slugs. Adults often eat smaller frogs, including juveniles of their own species. Northern Leopard Frogs may occasionally consume other vertebrates; voles, birds, and even garter snakes have been found in the stomachs of large frogs. Both nocturnal (active by night) and diurnal (active by
and green frogs...The Green Frog is an opportunistic feeder, its diet comprised primarily of arthropods, snails, and worms (Martof and others 1980).
Although some sites say that either will "eat anything that moves".
Bull frogs......American Bullfrogs are veracious predators, eating things like insects, smaller frogs, fish, small birds, and even small snakes.