Damselflies fold slim wings while dragonflies usually don’t
Damselflies are Zygoptera within order Odonata, cousins to dragonflies but typically smaller and slimmer. Most species rest with wings folded along the body, a silhouette field guide that separates them from many Epiprocta dragonflies. Around 2,942 species hunt other insects as both aquatic nymphs and flying adults.
Damselflies form the suborder Zygoptera, about 2,942 living species in 309 genera, and a 2021 molecular study largely confirmed the traditional families while rearranging Amphipterygidae, Megapodagrionidae and Protoneuridae. Apart from the spreadwings, they rest with wings held together above the body, whereas dragonflies hold theirs out flat; damselflies are also slimmer, and their eyes never meet. The smallest are the wisps of the genus Agriocnemis, while forest giants of the Pseudostigmatidae reach 19 centimetres across the wings in Megaloprepus.
Both nymphs and adults hunt other insects. Nymphs live in bogs, ponds, lakes and rivers, eat mostly water fleas and other crustaceans, and at the final moult climb out of the water to transform. Adults pluck flies and mosquitoes off stems and leaves with spiny legs rather than chasing prey in the air as dragonflies do, and a flexible neck joint lets them swivel the head while manoeuvring. Birds, fish, frogs, dragonflies, water beetles and giant water bugs all eat them in turn.
Males are often brighter than females, and mating pairs lock into a heart or wheel shape, the male gripping the female behind the head. Most individuals stay close to where they hatched, yet large male boreal bluets in British Columbia often migrate while smaller ones stay put. A few members of Caenagrionidae even breed in brackish water.
Because species need particular water and plants, odonates serve as gauges of ecosystem quality. The common blue damselfly thrives in fishless acid bog pools, while the scarce blue-tailed damselfly needs slow, base-rich water and tolerates zinc and copper in sediment. In Costa Rican rainforest the helicopter damselfly Mecistogaster modesta breeds in water trapped by bromeliads, reaching about 6,000 larvae per hectare. Anglers imitate the nymphs with wet flies, and jewellers turn the adults into brooches.
Source: Damselfly
