ABSTRACT
T he silverfish and their allies, referred to as Tbysanura in the past, are an interesting group of true insects, probably the most advanced of the existing primitive orders of wingless insects.
Diagnosis: L. 2.0--20 mm. Body soft, with flexible integument; shape flattened or convex, with or without scales. White, gray, brown, or ground color. Mouthparts with biting mandibles and two condyles. Antennae short, to nearly as long as the body, with many segments. Compound eyes small or absent, never meeting dorsally; ocelli absent, except in one family. Abdomen with short styli on segments 2 through 9, but sometimes absent on some segments. Median apical abdominal filament usually only slightly longer than the lateral cerci. The advanced structure of the mandibles shows this group to be very distinct from the Microcoryphia. Their resemblance is thought to be superficial only. Immature stages resemble the adults; there is no noticeable external metamorphosis. (Fig. 5.1.)
Fig. 5.1. General body form of adult.
