All Wingless Insect Orders (Apterygota)

The wingless insect orders are the two orders of primitively wingless insects, the Archaeognatha and the Thysanura, also called Zygentoma, the silverfish and firebrats. The Archaeognatha consist of about 350 known species that hide under bark, in litter and in rock crevices and feed on algae, lichens and vegetable debris, and they are called monocondylic because each mandible has only one articulation point. The Thysanura live under bark, in litter, in caves, in ant nests and in deserts, are omnivorous, and have a flattened body with long cerci and a median filament. The Thysanura share two mandibular condyles with the winged insects, a link that places them closer to those than to the Archaeognatha.