With more than 4,500 species of cockroach in the world, only a handful are considered pests. Several species perform well in captivity -- a few species are kept as pets while others are bred as feeders for other types of pets. Common pet species include the Madagascar hissing cockroach, death's head roach and Indian domino roach. Sexing your roaches is important whether they are pets or feeders: For feeders, it's important to know which roaches to feed to your pet; when breeding feeder roaches for reptiles or other pets, feeding male roaches is standard to protect against the risk of feeding a gravid female roach. Sexing pet roaches allows you to prepare for or reduce potential breeding.
Madagascar Hissing Cockroaches
Madagascar hissing cockroaches are among the most commonly kept pet species. These large roaches reach 2 to 4 inches in length and lack wings. The Madagascar hissing roaches are sexually dimorphic, meaning males and females differ in appearance. Compared to other pet roach species, the Madagascar hissing cockroach is much easier to sex just by looking.
This species has visible horns, called tubercles, on the insect's head. Males' tubercles are very large and pronounced whereas the females' are smaller and smoother.
Males' antennae are hairier in appearance than the smooth antennae of females; however, this trait may not be easy for every person to discern.
A third difference between males and females of this species is behavior. Males become rather aggressive with each other; they ram each other with their tubercles or "push each other with their abdomens."
Not all roaches can be sexed simply by looking at them, but generally mature adult females are larger than their male counterparts. As in many other insects, the larger female size allows for reproduction.
To reliably sex cockroaches, you must examine the segments on their abdomens. Hold the cockroach facing you so you are looking at its "belly." Females have a much wider and larger last segment -- known as a sternite -- than do males.