Morphology

The adult cockroach is 2-4 cm long and about 1 cm wide, with a body that is flattened dorso-ventrally, bilaterally symmetrical, segmented, and organised into three regions - head, thorax and abdomen - all encased in a hard, brown, chitinous exoskeleton. Each body segment's exoskeleton is built from hardened plates called sclerites, joined by a flexible arthrodial membrane; the dorsal plates are tergites, the ventral plates sternites, and the lateral plates pleurites. The small, triangular head is set at right angles to the body's long axis, with its mouthparts pointing downward (hypognathous), and carries a pair of large, immobile, kidney-shaped (reniform) compound eyes, a pair of sensory antennae, and biting-and-chewing (mandibulate) mouthparts made of a labrum, paired mandibles, paired maxillae, a labium and a hypopharynx. The thorax has three segments - prothorax, mesothorax, metathorax - each carrying one pair of the six walking legs (hence "hexapod"), and two pairs of wings: leathery forewings (tegmina) from the mesothorax that protect the membranous hindwings used for flight, which arise from the metathorax. The ten-segmented abdomen differs visibly between the sexes: males show anal styles and a longer, narrower abdomen with nine visible se …