Chapter 185 - Odonata: Dragonflies, Damselflies

Abstract

This chapter describes the odonata (dragonflies), an exopterygote aquatic insects. Dragonfly adults are predaceous, relatively long-lived insects. Their large compound eyes, strong chewing mouthparts, long legs, and unparalleled flight capabilities are ideal adaptations for catching and consuming insect prey. Although adult dragonflies have mastered the air, the immature stage (called nymph or larva) is aquatic and usually much longer lived. Adaptation to an underwater existence has resulted in striking differences in form among nymphs, whereas adults are much more uniform in shape. Dragonflies are quite harmless insects; they do not sting and will try to bite humans only when held captive. However, they are hosts of trematodes (flukes in the family Lecithodendriidae) in Southeast Asia, and when eaten raw, they can be a source of infection in humans (by ingestion of the metacercariae). On the whole, dragonflies are considered beneficial insects for several reasons. In both nymph and adult stages, they feed on many insects that are pests of humans and domestic animals, such as mosquitoes (Culicidae), deer flies (Tabanidae), black flies (Simuliidae), and other Diptera. They are important components of aquatic food webs and are used as indicators of ecological health of streams and lakes; in some areas, nymphs are used as fish bait or as food. They make good subjects for behavioral and ecological studies, and poets and visual artists are often inspired by their beauty and behavior.