For a long time, the order Orthoptera was a loosely interpreted group which has now been restricted to more homogeneous forms. The well known cockroaches which formed the family Blattidae are now considered as a séparate order under the name of Blattaria.

The cockroaches are so well known that there is no need for a detailed description of their morphology. They are easily separated from the other insects by their soft bodies, by their oval and flattened form; the antennae are often longer than the body and are composed of many short segments; the head when at rest, is bent under and almost concealed by the pronotum, so that the mouth projects back to the base of the front legs.