The Madagascar hissing cockroach (Gromphadorhina portentosa), originally from the island of Madagascar off the African coast, is one of the largest species of cockroach, reaching 2-3 inches at maturity. Unlike most cockroaches, they are wingless and are excellent climbers. They feed primarily on various types of vegetable material. They also shed their exoskeleton, emerging from their old bodies as a soft white and darken back to their recognizable rich brown as the days pass.