Birds: Birds such as chickadees, titmice, vireos, warblers, and woodpeckers are all voracious caterpillar eaters. They will often search for caterpillars on leaves and branches, and will eat them whole.
Spiders: Spiders are another common predator of caterpillars. They will often spin webs in areas where caterpillars are likely to be found, and will wait for them to become ensnared. Once a caterpillar is caught in a web, the spider will inject it with venom and then eat it.
Wasps: Wasps are also predators of caterpillars. They will often lay their eggs on caterpillars, and the wasp larvae will hatch and feed on the caterpillar. Some species of wasps will also paralyze caterpillars and then store them in their nests for later consumption.
Ants: Ants are another type of insect that eats caterpillars. They will often work together to attack and kill caterpillars, and then carry them back to their colonies to eat.
Beetles: Some species of beetles, such as ground beetles and ladybugs, will eat caterpillars. They will often search for caterpillars on the ground or on plants, and will eat them whole.
Parasitic Flies: Parasitic flies lay their eggs on or inside caterpillars. When the eggs hatch, the maggots feed on the caterpillar, eventually killing it.
Fungi: Some species of fungi, such as the caterpillar fungus, are parasitic on caterpillars. The fungus will infect a caterpillar and then grow inside its body, eventually killing it.