What eats cicadas? A better question is: what doesn’t eat cicadas?
Pretty much every creature with a mouth will eat a cicada, given the chance. Even organisms without mouths like fungi will consume cicadas.
People, pets, rodents, marsupials, reptiles, birds, fish, insects, arachnids — virtually any creature will eat them.
Some insects are known for specifically preying on cicadas, for example, Cicada Killer Wasps are well known for capturing cicadas for their larvae to eat them.
What eats them when they’re underground? When they’re underground they’re often eaten by moles and other furry insectivores, but enough of them escape the moles for the species to survive.
Read are cicadas safe to eat if you’re planning a cicada buffet.