Madagascar Hissing Cockroaches

The insects currently on display on the Insect Zoo Camera are giant hissing cockroaches (Gromphadorhina portentosa).

The Madagascar or giant hissing cockroach adult is a large insect that may reach a length of 10 cm and weight of 24 grams. These insects are wingless, sexually dimorphic, behaviorally complicated and good pets. The large island country of Madagascar is home to these cockroaches which inhabit forest floors feeding on leaf and fruit litter. Adults and immatures are dark brown with a tan abdomen. A row of dark brown spots, spiracles, can be seen along each side of the abdomen.

Spiracles are opening through which the insect respiratory system takes in air. The Madagascar hissing cockroach gets its name from the loud, startling hiss produced when the insect is disturbed. The roaches hiss by expelling air through modified spiracles on the fourth abdominal segment

Madagascar Hissing Cockroach adults display sexual dimorphism in the form of their shield-like pronotum. The pronotum in insects is the first segment of the thorax usually located directly behind the head. In hissing cockroaches the pronotum completely covers the head forming a protective shield from which two blunt horns protrude. The pronotal horns of the female are mere bumps whereas those of the male are prominent and result in the pronotum resembling the head of a frog.

The pronotal horns of males are used in territorial interactions with other males. Large males commonly can be seen pronotal-butting other males and pushing smaller male's abdomens. Adult males also employ hissing in territorial encounters, courtship and recognition.