The cockroach is a common species of insect, widely regarded as a pest due to their habit of living in or near human residences. Considered a large insect, some cockroaches, such as the Australian giant burrowing cockroach, can reach 3.5 inches in length. Despite their prominence and abundance, they have a large variety of predators, ranging from small beetles and centipedes to large birds and snakes. Even some parasitic wasp species are effective at destroying roach populations.
Lizards and Snakes
Most lizards, including more common varieties such as the gecko and monitor, are prolific insect predators. Insects comprise the majority of their diet and they happily consume cockroaches too. Lizards make popular pets, where roaches are often a staple diet. Other species of lizard commonly known to eat these insects are bearded dragon lizard and iguana. Smaller snakes, such as the rough green snake and ringneck, will eat cockroaches.
The Ampulex Compressa Wasp uses a unique method for survival and reproduction. The wasp lands on a cockroach and stings its brain. The venom causes the roach to descend into a trance-like state. It is alive, yet unable to defend itself from the wasp. The wasp then drags the victim to its nest or burrow where it proceeds to lay eggs on the underbelly. The eggs of the wasp eventually hatch and eat the cockroach, which is normally alive and still paralyzed.
Insects and Arachnids
Besides the parasitic wasp, various other insect species eat either cockroaches or their eggs. The praying mantis is known to kill them, as do centipedes. Some larger species of spider, such as the huntsman or brown recluse, keep cockroach numbers down and can be useful in homes if allowed to coexist with humans.
Frogs and toads happily feed off cockroaches, given the opportunity. Many insect-eating bird species also prey on them, though rarely get a chance due to the cockroaches' habit of living indoors and emerging predominantly at night.