Odonata (damselflies, devil's darning needles, dragonflies, horse-stingers; class Insecta, subclass Pterygota) Order of primitive insects, the earliest fossils of which are found in the Upper Carboniferous coal measures of Commentry (France). These slender-bodied insects have two pairs of large, glassy wings, and large, prominent eyes. They usually hunt on the wing, taking swarming flies and other flying insects. Odonates are unique in possessing two sets of genitalia (see ACCESSORY GENITALIA). The nymphs are aquatic, and catch prey with a prehensile organ (called the mask) derived from the labia (see LABIUM). Despite their fearsome common names, these beautiful insects are not dangerous to large animals. About 5000 species are known, with a cosmopolitan but mainly tropical distribution.

Odonata An order of exopterygote insects containing the dragonflies and damselflies, most of which occur in tropical regions. Adult dragonflies have a pair of prominent compound eyes, a compact thorax bearing two pairs of delicate membranous wings, and a long slender abdomen. They are strong fliers and prey on other insects, either in flight or at rest. The eggs are laid near or in water, and the newly hatched nymphs (naiads) are aquatic and resemble the adults, with rudimentary wings. They breathe through gills and feed on small aquatic animals. The nymph leaves the water for its final moult into the terrestrial adult.