Brown frogs are a broad term, so the specific diet will depend on the exact species. However, in general, brown frogs are carnivorous and their diet consists of:

* Insects: These are the staple food of most brown frogs, including flies, beetles, moths, crickets, grasshoppers, and ants.

* Other invertebrates: They also eat spiders, worms, snails, slugs, and even small crustaceans.

* Small vertebrates: Larger brown frog species might occasionally eat small fish, tadpoles, or even other frogs.

The size of the prey depends on the size of the frog. Smaller frogs eat smaller insects, while larger frogs can handle bigger prey.

Important note: Frogs don't have teeth. They swallow their food whole.