A cockroach is an insect of the order Blattodea, which also includes termites. About 30 cockroach species out of 4,600 are associated with human habitats. About four species are well known as pests. The cockroaches are an ancient group, dating back at least as far as the Carboniferous period, some 320 million years ago. Cockroaches are somewhat generalized insects without special adaptations like the sucking mouthparts of aphids and other true bugs; they have chewing mouthparts and are likely among the most primitive of living neopteran insects. They are common and hardy insects, and can tolerate a wide range of environments from Arctic cold to tropical heat. Tropical cockroaches are often much bigger than temperate species, and, contrary to popular belief, extinct cockroach relatives were often very large animals.
Cockroaches have appeared in human culture since classical antiquity. They are popularly depicted as dirty pests, though the great majority of species are inoffensive and live in a wide range of habitats around the world. Some species, however, do eat food resources that humans depend on, and socockroaches have been known to cause property damage worldwide; there is even a fossil record indicating that roach-like animals ate dinosaurs. Cockroaches can be found anywhere people live because they prefer warm temperatures (generally between 70°–80° Fahrenheit),:2 but can survive colder climates by hibernating or aestivating when necessary.:136–137 Large populations often congregate indoors during winter months for warmth; these aggregations may result in infestations.:157