- Also called:
- darner, devil’s arrow, or devil’s darning needle
- Related Topics:
- Odonata
- entomophagy
- globe skimmer
- Attenborough’s pintail
dragonfly
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What is a dragonfly?
A dragonfly is an insect belonging to the suborder Anisoptera within the order Odonata. Dragonflies are aerial predators, recognized for their agility and speed, often found near freshwater habitats. They have long bodies, two pairs of narrow, intricately veined wings, and large, bulging eyes that provide a field of vision approaching 360 degrees.
Dragonfly young, called larvae or nymphs, are aquatic predators. They consume mosquito larvae, worms, crustaceans, tadpoles, and small fish. Adult dragonflies are also voracious predators, feeding on flying insects like mosquitoes and flies. Dragonflies have been held in high regard in folklore and art, especially in Asian cultures. However, 16% of dragonfly and damselfly species are at risk of extinction due to habitat loss.
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What do dragonflies look like?
Adult dragonflies have long bodies and two pairs of narrow, intricately veined, membranous wings that may have colored markings. Unlike damselflies, the front and rear wing pairs are shaped differently. Dragonflies rest with their wings spread horizontally. They have a powerful build and are generally much stronger fliers than damselflies. Dragonflies also have huge bulging eyes that occupy most of the head, giving some a field of vision approaching 360 degrees.
The large wings are strengthened by a complex network of veins. Each wing also has a thickened patch (the pterostigma) on the leading edge of the wing tip. The forewings of dragonflies are narrower than the hind wings. The sloping thorax accommodates very large wing muscles and sets the legs forward, where they can best grasp prey.
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Where do dragonflies live?
Dragonflies are insects of the order Odonata, found throughout the world, with about 3,000 species inhabiting mostly freshwater habitats. They are most numerous and varied in the tropics but can be found as far north as the boreal forests of Siberia and North America, and as far south as the Southern Hemisphere (except Antarctica).
Dragonfly larvae, also known as nymphs or naiads, are aquatic and live in various shallow freshwater habitats like tree holes, ponds, marshes, and streams. They are often bottom-dwelling, with mottled or drab colors that camouflage them among sediments or water plants. Adult dragonflies are strong fliers and are usually found flying near water.
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How do dragonflies catch their food?
Dragonflies are among the fastest insects and most effective aerial predators, eating mosquitoes, flies, and sometimes prey that is 60% of their own weight. Their agility and speed help them capture small flying insects.
Dragonfly larvae, also dedicated predators, possess a unique structure called a "mask," which is a fusion of the larva’s third pair of mouthparts. At the end of the mask is a set of fang-like pincers used to seize prey such as mosquito larvae, worms, crustaceans, tadpoles, and small fish.
Adult dragonflies have exceptional vision, with huge, bulging eyes occupying most of their head, giving them a field of vision approaching 360 degrees. Some dragonfly species have regions of increased resolution on their eyes, which they use to spot flying insects.
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What is the life cycle of a dragonfly?
The dragonfly life cycle begins with eggs laid in or near water, either inside plant tissue or dropped onto the water's surface. The eggs hatch into aquatic larvae, also known as nymphs or naiads, which are dedicated predators.
These functionally wingless larvae possess a unique anatomical structure called the "mask," which is a fusion of mouthparts used to seize prey. They absorb oxygen from the water through gills inside their rectum and can use jet propulsion to escape danger.
As the larva grows, it molts, with wing sheaths becoming apparent about halfway through development. Eventually, the larva crawls out of the water and molts one last time, emerging as a soft, pale, reproductively immature adult, leaving behind a cast skin. The adult dragonfly then flies away from the water to feed and mature. Adult life consists of prereproductive and reproductive periods. Dragonflies exhibit a unique mating posture, with the male grasping the female's head to form a "wheel" position for sperm transfer. After mating, the female lays eggs, either alone or with the male still attached. Some dragonfly species are migratory.
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How are dragonflies important to their ecosystems?
Dragonflies are important to their ecosystems as both larvae and adults. Dragonfly larvae are aquatic predators that feed on various small water animals, including mosquito larvae, worms, crustaceans, tadpoles, and small fish. Adult dragonflies are aerial predators that feed on small flying insects, such as mosquitoes and flies. Because they are nonmigratory and stay in small areas throughout their lives, macroinvertebrates such as dragonfly larvae are good indicators of the environmental health of streams and waterways.
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dragonfly, (suborder Anisoptera), any of a group of roughly 3,000 species of aerial predatory insects most commonly found near freshwater habitats throughout most of the world. Damselflies (suborder Zygoptera) are sometimes also called dragonflies in that both are odonates (order Odonata). Extremely strong and agile fliers, dragonflies are among the fastest insects known and are voracious predators of flying insects such as mosquitoes and flies.
In 2021 the International Union for Conservation of Nature (IUCN) released the first global assessment of dragonflies as an update to their Red List of Threatened Species. The study found that widespread habitat loss in wetlands and along rivers is contributing to the decline of dragonfly species around the world, with 16 percent of dragonflies and damselflies now at risk of extinction.
- Kingdom: Animalia
- Phylum: Arthropoda
- Class: Insecta
- Order: Odonata
- Suborder: Anisoptera
See also list of insects.
Distinguishing characteristics and flight behavior
Adult dragonflies are characterized by long bodies with two narrow pairs of intricately veined, membranous wings that, while generally transparent, may have colored markings. Unlike damselflies, the front and rear wing pairs are shaped differently. In addition, dragonflies rest with their wings spread horizontally, rather than held vertically against each other (with the exception of one very small family, Epiophlebiidae). Dragonflies have a more powerful build and are generally much stronger fliers than damselflies. Dragonflies also have huge bulging eyes that occupy most of the head, giving some a field of vision approaching 360 degrees.
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The winged adults are diversely colored in a variety of shades ranging from metallic to pastel. Compared with other insects, they are large, with some having wingspans of up to 16 cm (about 6 inches). Even the smallest species are about 20 mm (0.8 inch) across. Dragonfly wing muscles must be warm to function optimally, and so, if cool, the insect often engages in wing-whirring and basking in the sun to generate heat before taking flight. The dragonfly’s speed and agility contribute to its being one of the most effective aerial predators. Small flying insects, such as mosquitoes, are the usual fare, but some dragonflies regularly consume prey that is 60 percent of their own weight.
Life cycle and reproduction
Young dragonflies, called larvae or sometimes nymphs or naiads, are aquatic and are as dedicated predators under water as the adults are in the air. The functionally wingless larvae are usually mottled or dull in color, matching the sediments or water plants among which they live. They have bulging eyes somewhat similar to the adults, but possess a formidable anatomical structure not present in the adult. Called the “mask,” it is a fusion of the larva’s third pair of mouthparts. Disproportionately large, the mask folds beneath both the head and thorax when it is not in use. At the end of the mask is a set of fanglike pincers used to seize prey such as mosquito larvae, worms, crustaceans, tadpoles, and small fish. Different species of dragonfly larvae can be described as sprawlers, burrowers, hiders, or claspers. Their shape, metabolism, and respiration differ concordantly with the microhabitat they occupy.
Larvae crawl from eggs laid in or near water. Some species lay their eggs inside plant tissue, others attach their eggs to substrates at or above the water’s surface, and some may drop or wash their eggs from their abdomen onto water. Larvae absorb oxygen from the water using gills inside the rectum. The abdomen draws water in and pumps it out again through the anus. Water can be forcibly expelled in this way, resulting in jet propulsion as a means of escape. Solid waste is also expelled in this manner. As the larva grows, it molts, its future wings first becoming apparent about halfway through the larva’s development. These wing sheaths then enlarge rapidly with each successive molt. Eventually, the larva crawls out of the water (often at night) and molts one last time, emerging as an adult and leaving behind a cast skin (exuvia).
Dragonflies, like damselflies, exhibit a mating posture unique to the Odonata. The male and female contort themselves into the “wheel” position before sperm is transferred. Before and after mating, dragonflies often fly in tandem, with the male towing the female in flight using claspers at the tip of his abdomen to grip the back of her head. Pairs of some species may remain in tandem while the female lays her eggs.
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Some dragonfly species are migratory. The globe skimmer (or wandering glider, Pantala flavescens), for example, makes an annual multigenerational journey of some 18,000 km (about 11,200 miles); to complete the migration, individual globe skimmers fly more than 6,000 km (3,730 miles)—one of the farthest known migrations of all insect species.
Descriptive names
Many dragonfly families have descriptive common names associated with their scientific names. Examples include the hawkers (Aeshnidae), petaltails (Petaluridae), and clubtails (Gomphidae). Numerous other names related to neither taxonomy nor fact have traditionally been applied to dragonflies, such as horse stinger. Dragonflies have also been known as “snake doctors” in the American South, owing to the superstition that they nurse ill snakes back to health. The term devil’s darning needle is derived from a superstition that dragonflies may sew up the eyes, ears, or mouth of a sleeping child, especially one who has misbehaved. In reality, dragonflies present no danger to humans.