Unlike most cockroaches, they are wingless (though this is also true of some other wood-dwelling roaches).
The Madagascar Hissing Cockroach Gromphadorhina portentosa, also known as Hissing roach or simply Hisser, is one of the largest species of cockroach, reaching 4 to 5 inches at maturity. They are excellent climbers and can easily scale smooth glass.
Males can be readily distinguished from females by their thicker, hairier antennae and the pronounced "horns" on the pronotum. Females carry the ootheca (egg case) internally, and release the young nymphs only after the eggs have hatched. As in some other wood roaches, the parents and offspring will commonly remain in close physical contact for extended periods of time.