Mandibles and first maxillae modified as piercers; second maxillae fused to form a jointed, grooved rostrum. Wings usually present. Four Malpighian tubes. Cerci absent. Ovipositor developed.

Includes two sub-orders:—

1. Heteroptera: Rostrum not in contact with haunches of fore-legs. Fore-wings partly coriaceous. Young resembling adults.

Includes the bugs, terrestrial and aquatic.

2. Homoptera: Rostrum in contact with haunches of fore-legs. Fore-wings uniform in texture. Young often larvae. Penultimate instar passive in some cases.

Includes the cicads, aphides and scale-insects (see [Hemiptera]).

Order: Anoplura.

Piercing jaws modified and reduced, a tubular, protrusible sucking-trunk being developed; mouth with hooks. Wingless, parasitic forms. Cerci absent. Four Malpighian tubes. Young resembling adults.

Includes the family of the Lice (Pediculidae), often reckoned as Hemiptera (q.v.). See also [Louse].

Sub-class: Endopterygota.