Class Insecta - Insects

arrangement of major extant taxa based on molecular data in (1)

Insecta Linnaeus 1758

worldwide

aquatic marine forms conspicuously absent

Hemimetabolous insects (e.g., dragonflies, mayflies, true bugs, grasshoppers) undergo gradual, or incomplete, metamorphosis. Immature stages (usually called nymphs) go through a series of molts, gradually assuming an adult form. Since the wings develop on the outside of the body, these groups are called exopterygotes. Some orders have immature stages that are aquatic. These possess specialized structures for aquatic life, such as gills, and are called naiads, or by some authors larvae.

Holometabolous insects (Endopterygota or Holometabola) have a four-stage life cycle: egg, larva, pupa, and adult (imago).

All the winged insects (including those who have lost their wings over the course of history) constitute a taxon called Pterygota (sometimes treated as a subclass).

orders alphabetically

Stork N.E. (2018) How many species of insects and other terrestrial arthropods are there on Earth? Ann. Rev. Entomol. 63: 31‒45. Full text