The body of a cockroach is narrow, elongated, bilaterally symmetrical, segmented and dorsoventrally flattened. Their size ranges 0.6-7.6 cm and has long antennae, legs and a flat extension of the body wall that conceals the head. The adults of the most common species of cockroach, Periplaneta americana, are about 3.4-5.3 cm (34-55 mm) long with wings that extend beyond the tip of the abdomen. The body colour is reddish-brown, sometimes black, with a pale yellow at the last segment of the body and externally covered by a chitinous exoskeleton. The exoskeleton protects the body and provides rigidity and surface for the attachment of muscles. It also prevents the loss of water from the body. The chitinous plates are called sclerites.