MADAGASCAR HISSING COCKROACH

Characteristics

Madagascar’s hissing cockroach is one of the largest species of cock­roach in the world, up to four inches long, with males grow­ing larger than fe­males. It has the usual equipment of an insect: head, tho­rax, ab­domen, and six legs. However, they do not have wings. Their ex­oskele­ton is dark, from ma­hogany brown to black, and thick, hard, and waxy. They have pads and hooks on their feet that allow them to climb both rough and smooth sur­faces. Males have a pair of large hornlike bumps on their head that are called prona­tal humps. Females have them as well, but they are much smaller.

Foods and Feeding

Mada­gas­car hiss­ing cock­roaches are de­tri­ti­vores, feeding on dead organic material. Their most fre­quent food is de­cay­ing plants, in­clud­ing fallen fruit, which is read­ily avail­able in the rainforest. They also eat fungi, smaller in­sects, and an­i­mal car­casses. As part of the forest “clean-up crew,” they play an important role in the rain­forests of Mada­gas­car by consuming a large amount of de­cay­ing plant and an­i­mal mat­ter. They recycle the nutrients to make them available in the food web again, and they help prevent decaying matter from piling up and negatively affecting tree roots, soil, and other animals.

Behavior

Hissing cockroaches spend most of their time on the forest floor, hanging out in rotting logs, leaf litter, and other detritus. They are noc­tur­nal and tend to avoid light. At night, they become more active and venture out to scavenge for food. Males es­tab­lish ter­ri­to­ries that they de­fend from other adult males. Ag­gres­sive hiss­ing and pos­tur­ing warns potential interlopers away, and its usually the male that is larger and hisses more that wins. One dominance behavior is standing up on their “toes,” which is called stilt­ing. If necessary, the males will fight, tussling and pushing each other with their prona­tal humps, although fights rarely result in injury. Fe­male hissing cockroaches, on the other hand, are more so­cial and do not fight with one an­other or with males.

The Mada­gas­car hiss­ing cock­roach is unique in its abil­ity to hiss. This sound is produced by forcibly expelling air through a pair of modified abdominal spiracles—breathing pores that are part of the respiratory system of insects. This hiss­ing sound is used to com­mu­ni­cate. Four hisses with dif­fer­ent pur­poses and pat­terns have been iden­ti­fied: a male com­bat hiss, two types of court­ing and mat­ing hisses, and an alarm hiss, which is a loud, snake-like hiss­ing that star­tles preda­tors.

Reproduction and Life Cycle

Cock­roach mat­ing can occur year around, but only when the cli­mate is warm. When courting females, male hiss­ing cock­roaches typ­i­cally pro­duce two types of hissing sounds as sig­nals, a call­ing sound and a courtship sound. The call­ing sound is a long dis­tance song that is used to at­tract fe­males, while the courtship sound is used more dur­ing close range in­ter­ac­tion.

Male hiss­ing cock­roaches are at­tracted and stim­u­lated by the odor of the fe­male, which they pick up with spe­cial­ized sense or­gans on their an­ten­nae. The amount of at­trac­tant se­creted is higher in young fe­males, al­though the out­put can be spo­radic, and it de­creases with age. When the male is at­tracted to the fe­male by this scent, he be­gins to hiss and touch her an­ten­nae. The pair then at­taches to one an­other and turns rear to rear, and they re­main in this po­si­tion for 30 min­utes for fertilization.

Mada­gas­car hiss­ing cock­roaches have an interesting form of producing young. They are ovoviviparous—the female develops eggs, but she keeps them inside her body in a long, yellowish egg case called an ootheca. When the eggs hatch, the female then releases the young, called nymphs, typically 15 to 40 of them. The nymphs are quite sim­i­lar to adults in gen­eral struc­ture, but they lack re­pro­duc­tive or­gans. Nymphs molt their ex­oskele­ton six times as they grow to adult­hood, a process that usu­ally takes six to seven months.

Conservation and Threats

While Madagascar hissing cockroaches are not a threatened or endangered species, they are dependent on healthy forest ecosystems—and the forests, in turn, are dependent on them.