Thysanura

In this order the insects average much larger than the Collembola. The abdomen is composed of 11 segments and at its end is a pair of cerci, thread-like except in a few species in which they resemble forceps. Styli, slender appendages, each having two segments, occur on the underside of the abdomen and sometimes on some of the thoracic segments, the former attached to large plates believed to be the bases of former abdominal legs. In some Thysanura the body is covered by scales suggesting those of butterflies. The order may be described as

Apterygota with styli on the underside of the abdomen; usually with slender, many-segmented cerci or forceps-like structures at the end of the body; abdomen of 11 segments.

Only one thysanuran is of particular economic importance in the United States, the silverfish or "slicker".