Insects with No Metamorphosis

Ametabolous insects are wingless as adults and the only apparent differences from the nymph to adult stage is in overall size. The immatures get larger as they molt until they are sexually mature. The only insects with no metamorphosis occur in the subclass Apterygota and include the orders Protura, Diplura, Microcoryphia, Thysanura, and Collembola. Here we will provide characteristics for identifying the Thysanura, or silverfish.

Order Thysanura (Silverfish, Bristletail, or Firebrat)
Silverfish are moderately sized insects that are generally elongated and flattened. They have three appendages on their abdomen: one pair of cerci and a median caudal filament. They also have widely separated compound eyes. The Microcoryphia or jumping bristletails are a closely related order that are similar in appearance. However, the bristletails are slightly more cylindrical and the thorax is somewhat arched.