Cockroach: Paraphyletic group of winged insects of the order Blattodea

There are 4,000 species. About 30 species invade human homes. This is less than 1% of all the cockroach species. Four species are pests.

The families of Mantodea, Isoptera, and Blattaria are usually combined by entomologists into a larger group called Dictyoptera. Current evidence strongly suggests that termites have evolved directly from true cockroaches, and many authors now consider termites to be in the family of cockroaches.

Historically, the name Blattaria has been used largely interchangeably with the name Blattodea. Blattodea refers to a larger group that includes fossil groups related to roaches, but not true cockroaches themselves. These earliest cockroach-like fossils ("Blattopterans" or "roachids") are from the Carboniferous period between 354–295 million years ago. However, these fossils differ from modern cockroaches in having long ovipositors and are the ancestors of mantis as well as modern cockroaches. The first fossils of modern cockroaches with internal ovipositors appear in the Lower Cretaceous. A proposed phylogeny of the families is shown in the diagram.

Cockroaches in the broader sense (Blattodea) have existed a very long time. The earliest cockroach fossils are 354–295 million years old. Science student, Cary Easterday, found a giant 300 million year old fossil cockroach 9 cm (4 in) long, in a coal mine in Ohio.

Most cockroaches are omnivores. They are tough, and hard to kill. A cockroach can live for two weeks without a head.

Cockroaches become adults in 3-4 months and can live up to one year. A female German cockroach can produce 8 egg cases in her lifetime and each egg case may contain 30-40 eggs.

Cockroaches are eaten as snacks and used for medicine in China.

The 1996 MTV musical movie Joe's Apartment had 5,000 singing cockroaches. Some parts of the movie were made with clay roaches and some with real roaches.

In the 1996 computer game Bad Mojo, the main character is turned into a cockroach and must move through a building to get back to his human body.