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Madagascar Hissing Cockroach. Life History.
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Life History • Female hissing roaches lay their eggs in a purse-like capsule known as an ootheca. This egg case is retained within the body until the eggs hatch, and the young roaches first see the world as tiny nymphs. You may occasionally see a female with the ootheca hanging outside of her body. She is in the process of forming the ootheca. Once it is completely formed she will retract it into a special cavity in the tip of her abdomen.
A female that has been successfully fertilized will retain the eggs within this cavity for at least 60 days.
The nymphal roaches must molt, or shed their skin, several times to reach adulthood just like lizards and snakes. In hissing roaches, the skin or casing splits down the middle of the back and the roach slowly wiggles its way out. The newly-molted roaches are very whitish. The new skin takes many hours to harden, and as it does so the roach gradually darkens to its normal coloration.
The nymphal roaches will molt six times during the course of their lives. The last molt occurs about five months after the nymph was born. At this last molt the nymphal roaches become sexually mature adults. Adult roaches never molt again. They may live for two or more years.
Courtship begins with the male and female stroking the other's antennae with their own. The pair then proceed to body stroking. All of this antennal stroking is accompanied by a subdued mutual hissing. Once attached to each other, male and female stretch out so they are facing in opposite directions. They may remain in this position for 20-30 minutes.
There are three ways to determine the sex of the cockroach. The easiest is to look at the thorax. The thorax is the second of the three sections into which the roach body is divided. The first section is the head, and the third one is the abdomen. The part of the thorax that is just behind the head is called the prothorax. In both sexes the upper surface of this prothorax is developed into two protuberances. In the females the development is slight. In the male, in contrast, the protrusions stand out, making the prothorax appear to be the head of a vertebrate animal.
The second way is to look at the feelers or antennae. The antennae are long, whip-like structures found on the head. Adult males have antennae with many laterally-projecting sensory hairs. These hairs give their antennae a fuzzy look, especially near the base. The antennae of the female lack these hairs. • The third way of determining sex is to look at the tip of the abdomen, or third section of the body. At the tip of the abdomen there is a ventral plate. In the male this plate is much narrower than in the female.
The hiss is produced by a pair of spiracles, or breathing tubes, on the fourth segment of the abdomen (counting from the front). A pair of spiracles is present on most of the abdominal segments. These spiracles allow air to seep deep within the tissues where it can oxygenate the muscles. The spiracles also allow carbon dioxide to diffuse outward and escape from the body. All the spiracles have a constant inflow and outflow of gases, however, those on the fourth segment have been modified to take advantage of this flow to produce a sound, much as in a wind instrument.
