Insects of the order Odonata (odonates) are divided in two suborders: Zygoptera and Epiprocta. Zygoptera include the broad-winged damsels, spreadwings, pond damsels, and shadowdamsels. They can generally be recognized by the fact that (a) the wings at rest are held parallel to the body (except in spreadwings), (b) the fore- and hindwings are similar, and (c) the eyes are separated. Most species of the suborder Epiprocta belong to the infraorder Anisoptera, which includes the darners, clubtails, spiketails, and skimmers. In Anisoptera, (a) the wings at rest are held perpendicular to the body, (b) the hindwings broaden at the base, and (c) the eyes come close to or touch each other at the top of the head. Zygoptera are often smaller and have a weaker flight than Anisoptera.
All odonates have the same basic body plan consisting of a head, thorax carrying three pairs of legs and two pairs of wings, and abdomen. Most of the head consists of the compound eyes and the mouth and associated parts. The thorax contains the muscles that control the movements of the wings and legs whereas the abdomen, which is divided in 10 segments, contains the digestive and reproductive systems.
Within each suborder of odonates, identification often relies on examination of the coloration of various body parts. As illustrated by pictures on this web site, coloration within a species can, however, vary considerably. Factors influencing coloration include age, sex, reproductive status, and temperature. In addition, mature females of somedamselfly species come in two forms: an andromorph (male-like) and a less colorful heteromorph forms. Consequently identification, particularly of damselflies, cannot in many cases rely exclusively on coloration, but requires examination also of structural features, such as the shape and size of terminal appendages. Below are drawings showing the main external structural characteristics of dragonflies and damselflies.