Its body is divided into three segments: head, thorax and abdomen. Cockroach Periplaneta americanais a terrestrial, nocturnal, omnivorous, unisexual, oviparous insect. Body covered by a chitinous, hard exoskeleton of hard plates called sclerites.

(1) Head : Triangular, formed by fusion of 6 segments. Bears a pair of antennae, compound eyes. Mouth parts consists of labrum (upper lip), a pair of mandibles, a pair of maxillae, labium (lower lip), hypopharynx (acts as tongue). 

(2) Thorax : 3 segments; prothorax, mesothorax and metathorax. 

Bears 2 pairs of wings : 

Forewings : tegmina (mesothoracic). 

Hindwings : transparent, membranous (metathoracic) and 3 pairs of legs in thoracic segments. 

(3) Abdomen : 10 segments. Bears a pair of long, segmented anal cerci in both sexes and a pair of short, unjoined anal styles in males only. 

Also has anus and genital aperture at the hind end. Genital aperture surrounded by external genitalia called gonapophysis or phallomere.