Dragonfly

Lore & Background

Dragonflies are predatory insects, both in their aquatic nymphal stage (also known as 'naiads') and as adults. In some species, the nymphal stage lasts up to five years, and the adult stage may be as long as 10 weeks, but most species have an adult lifespan in the order of five weeks or less, and some survive for only a few days. They are fast, agile fliers capable of highly accurate aerial ambush, sometimes migrating across oceans, and often live near water. They have a uniquely complex mode of reproduction involving indirect insemination, delayed fertilisation, and sperm competition. During mating, the male grasps the female at the back of the head, and the female curls her abdomen under her body to pick up sperm from the male's secondary genitalia at the front of his abdomen, forming the 'heart' or 'wheel' posture. Fossils of very large dragonfly-like insects, the Meganisoptera or griffenflies, are found from 325 million years ago in Upper Carboniferous rocks; these had wingspans up to about 71 cm, though they were only distant relatives. True dragonflies first appeared during the Early Jurassic.

In Their Own Story

The afternoon sun glinted off the surface of the stagnant pond, turning lily pads into emerald islands. Suddenly, a flash of iridescent blue sliced through the humid air. A Common Blue Dart dragonfly hovered with impossible stillness, its wings a blur against the heat haze. Below, a mosquito drifted lazily on an updraft, unaware it had entered the kill zone. In a fraction of a second, the dragonfly shifted its trajectory. It didn't chase; it intercepted. With precision that defied physics, it angled its body, extended its spiny legs into a perfect basket, and snatched the mosquito from the air. There was no struggle, only the silent efficiency of an apex predator. Satisfied, the insect banked sharply, its wings catching the light in a spectrum of blues and greens, before vanishing back over the reeds to hunt again.

Reader's Guide

Dragonflies can be mistaken for the closely related damselflies, which make up the other odonatan infraorder (Zygoptera) and are similar in body plan, though usually lighter in build; however, the wings of most dragonflies are held flat and away from the body, while damselflies hold their wings folded at rest, along or above the abdomen. Dragonflies are agile fliers, while damselflies have a weaker, fluttery flight. Dragonflies make use of motion camouflage when attacking prey or rivals. Dragonflies live on every continent except Antarctica. Most Anisoptera species are tropical, with far fewer species in temperate regions. Dragonflies live from sea level up to the mountains, decreasing in species diversity with altitude. Their altitudinal limit is about 3700 m, represented by a species of Aeshna in the Pamirs.

Did You Know?

• The infraorder Anisoptera comes from Greek 'anisos' meaning 'unequal' and 'pteron' meaning 'wing' because dragonflies' hindwings are broader than their forewings.
• Dragonflies are represented in human culture on artefacts such as pottery, rock paintings, statues, and Art Nouveau jewellery.
• They are symbols of courage, strength, and happiness in Japan, but seen as sinister in European folklore.
• The globe skimmer Pantala flavescens is probably the most cosmopolitan dragonfly, occurring on all continents in the warmer regions.