Blattaria  

Blattodea contains over 4500 species worldwide, with about 150 species in Europe. They are among the most ancient winged insects, the earliest fossils dating back to the Carboniferous. The group is well defined by a combination of characters: eggs usually contained in oothecae (egg cases), leathery forewings, male genitalia asymmetrical and cerci* with one or more segments. Most cockroaches are tropical and found in a wide variety of habitats such as dead or decaying leaves or trees, caves, under stones, in nests of social insects etc. Cockroaches are mostly scavengers eating organic material. Less than 1% (30 species) are associated with humans, but these species contribute to the unpopular reputation of these insects. Cockroaches exhibit diverse reproductive biology. Most species have sexual reproduction, but some populations of Pycnoscelus surinamensis are parthenogenetic. These hemimetabolous insects produce hardened oothecae deposited on a substrate or membraneous oothecae that are incubated in a brood sac within the female’s body. Some species exhibit a high level of parental care.

*Cercus (sg.), Cerci (pl.): paired sensory structures at the posterior end of some arthropods.

Cockroaches are mostly nocturnal insect, with biting mouthparts and legs that are adapted for swift running. The body is oval and dorsoventrally flattened, allowing the animals to hide in narrow spaces, for example under bark or in crevices of trees and rocks. The head is usually hidden beneath the pronotal shield, and there is a pair of short cerci at the end of the abdomen.  In winged species, the forewings (tegmina) are leathery and protect the delicate hindwings.   

Most cockroaches are scavengers, with fairly broad diets, but a few species in the family Cryptocercidae specialize on dead and decaying wood.  Some cockroaches invade human dwellings and are significant household pests.

The great majority of roach species never bother people. They live outside, and are a harmless part of foodwebs.

There are over 4,000 species of roaches spread all around the globe, and lots more still unknown to science. In Michigan there are only a couple of dozen species, and about half of them are invaders that came along with European settlers.

Biogeographic Regions: nearctic (Native ); palearctic (Native ); oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native )