Corrodentia: an ordinal term meaning gnawers: net-veined or wingless: mandibulate, mouth formed for gnawing; transformation incomplete; thorax incompletely agglutinated: = Psocoptera: includes Termitidae, Psocidae and Mallophaga.

Isoptera: equal winged: an ordinal term for insects with four, similar, net-veined wings; mouth mandibulate; thoracic rings similar, loosely jointed metamorphosis incomplete: the Termitidae.

Thysanura: fringe-tails; wingless, mandibulate insects without metamorphosis; with anal appendages; body covered with scales; thoracic segments similar.