50 Fun Facts About Dragonfly

Dragonflies belong to which insect order, shared with damselflies?

Diptera are the true flies, Neuroptera the lacewings and Ephemeroptera the mayflies.

The dragonfly infraorder Anisoptera means 'unequal wings' because of what?

Damselflies, the Zygoptera or 'paired wings', have fore and hind wings of similar shape.

Roughly how many species of dragonfly exist?

They are classified into 348 genera and 11 families, and most live in the tropics.

An adult dragonfly's compound eye contains nearly how many facets (ommatidia)?

The eyes meet on top of the head in most families and give complete vision of the frontal hemisphere; there are three simple ocelli too.

At rest, how does a dragonfly hold its wings, unlike a damselfly?

Damselflies fold theirs along or above the abdomen and have a weaker, fluttery flight and widely separated eyes.

What is the immature aquatic stage of a dragonfly called?

In some species it lasts up to five years, far longer than the adult's few weeks in the air.

How long is the adult stage for most dragonfly species?

A few live as long as ten weeks; the underwater nymph stage can last up to five years.

The mating posture in which the male grips the female's head and she curls her abdomen forward is called what?

The male transfers sperm to secondary genitalia at the front of his abdomen before mating, a system found almost nowhere else in insects.

Giant 'griffenflies' with 75 cm wingspans lived in which period, 325 million years ago?

They were only distant relatives; true dragonflies did not appear until the Early Jurassic.

Fossils of the giant griffenfly Meganeura were first found in 1880 in coal measures in which country?

The Commentry shales were worked by mining engineer Henri Fayol, who passed the fossils to palaeoentomologist Charles Brongniart.

One hypothesis for Meganeura's giant size links it to high levels of what in the ancient atmosphere?

The idea is contradicted by giant griffenflies persisting into the Late Permian after oxygen dropped, so the absence of other aerial predators is another suspect.

Dragonflies belong to a group called Palaeoptera, meaning 'ancient-winged', because they cannot do what?

Mayflies share the trait; most modern insects can tuck their wings flat over the back.

Which is the only continent with no dragonflies?

They are absent from Iceland too, apart from strays blown in on the wind, and the treeline emerald in Arctic Alaska is the most northerly species.

Which dragonfly is probably the most widespread, found on every continent in the warmer regions?

Pantala flavescens is also called the wandering glider; on Rapa Nui it has a black-winged form.

Pantala flavescens makes an annual multigenerational migration covering roughly how far?

Individuals fly more than 6,000 km of it, one of the longest journeys of any insect; Amur falcons crossing the Indian Ocean may snack on them en route.

Dragonfly legs are used for perching and grabbing prey but not for what?

Males have a row of spines on each front leg modified into an 'eyebrush' for cleaning the compound eye.

A dragonfly nymph catches prey by shooting out which extendable mouthpart, sometimes called a mask?

It is fired by hydraulic pressure from the abdominal muscles and takes mosquito larvae, tadpoles and small fish.

How can a dragonfly nymph move with sudden speed through a pond?

The internal gills sit in a chamber in the abdomen; water pumped for breathing doubles as jet propulsion.

Freshly emerged adult dragonflies, still pale before their colours develop, are known as what?

The empty nymph skin left behind is the exuvia; a waxy blue 'pruinosity' on some adults wears off during mating.

In how many directions can an adult dragonfly propel itself in flight?

Up, down, forward, backward, left and right; the fore and hind wings can beat out of phase for hovering.

Large dragonflies such as hawkers reach top speeds of roughly what?

Old claims of 97 km/h for the southern giant darner are unreliable; cruising speed is about 16 km/h.

Dragonflies can fly about 100 body lengths per second forwards; how many backwards?

Counter-stroking, with forewings 180 degrees out of phase with hindwings, powers hovering and slow flight.

Dragonflies have been recorded pulling how many g in a sharp turn while chasing prey?

They also accelerate at 4 g in a straight line thanks to a very high power-to-weight ratio.

In an enclosure study, dragonflies caught up to what share of the fruit flies they pursued?

Success rose with prey density; erratic prey flight was the main way a fly escaped.

Dragonflies use which technique, also used by fighter pilots, when closing on prey or rivals?

By keeping a fixed bearing to the target it appears not to move, only to grow larger.

What rapid vibration do some large dragonflies use to warm their flight muscles before dawn?

Migratory darners do it to get an early start; the obelisk posture, by contrast, is used to avoid overheating.

Dragonflies sometimes lay eggs on cars, gravestones and solar panels because these surfaces mimic water how?

Shiny surfaces polarise light the way a pond does, and the insects gather to lay eggs on them.

Which family of dragonflies, the clubtails, prefers running water rather than still ponds?

The Libellulidae, or skimmers, favour still water; the burrowing clubtail nymphs breathe through a snorkel-like tube while buried in mud.

Which large migratory dragonfly is the official state insect of Washington?

Anax junius travels from the northern United States to Texas and Mexico and is the best-studied North American migrant.

Anax imperator, the largest dragonfly across most of Europe including Britain, is known as what?

Also called the blue emperor, its range has pushed north and uphill since the 1990s.

The helicopter damselflies of tropical America, with wingspans up to 19 cm, feed mainly on what?

They hover near an orb web and snatch the spider or its wrapped prey; Megaloprepus is the widest-winged of all living odonates.

The nymphs of Phanogomphus militaris may act as parasites, feeding on the gills of what?

It is a rare exception in a group that is otherwise a straightforward predator at every stage of life.

Old names for Japan such as Akitsushima have been interpreted as meaning what?

Legend says the mythical first ruler Jimmu was bitten by a mosquito which a dragonfly then ate; the insect symbolises courage, strength and autumn there.

For the Navajo, the dragonfly is a symbol of what?

Stylised as a double-barred cross, it is also a common motif on Zuni pottery and Hopi rock art.

In which country are adult dragonflies caught on birdlime-coated poles and fried in oil as a delicacy?

In China and Japan, by contrast, they have traditionally been used in medicine rather than eaten.

Folk names like 'devil's darning needle' and 'horse-stinger' reflect what myth about dragonflies?

European folklore cast them as sinister, whereas Japan made them emblems of happiness and rebirth.

Which art movement made the dragonfly a favourite motif, especially in jewellery?

René Lalique's dragonfly-woman corsage ornament of 1897 is the most famous example.

Which Victorian poet described a dragonfly 'like sapphire mail' in The Two Voices (1842)?

H. E. Bates later wrote of an endless procession of small sapphire dragonflies over water lilies in Down the River.

Japanese children traditionally catch large dragonflies using what thrown into the air?

The dragonfly mistakes the whirling pebbles for prey and tangles in the hair.

Which country lost over 60% of its wetlands last century, leaving dragonflies reliant on rice paddies?

Habitat degradation is the main threat to dragonflies worldwide; ponds, creeks and paddies now do the work of vanished marshes.

On a hot day, how do some dragonflies cool down?

They often dip three times in quick succession; others adopt the obelisk posture, pointing the abdomen at the sun to reduce exposure.

How many simple eyes, or ocelli, does a dragonfly have besides its two compound eyes?

The head locks onto the thorax with a system of hairs and muscles unique to the order, activated when feeding or flying in tandem.

The scientific study of dragonflies and damselflies is called what?

Fabricius coined the order's name in 1793 from the Greek for 'tooth', probably referring to the toothed maxillae.

Where do dragonfly nymphs keep their gills?

Damselfly nymphs instead breathe mostly through three feathery external gills at the tail.

What colour are dragonfly nymphs usually, to blend in on the pond bottom?

The adults are the showy ones: their blues come from cuticle microstructures and greens from a structural blue mixed with yellow pigment.

Which small falcons are fast enough to catch adult dragonflies on the wing?

Amur falcons crossing the Indian Ocean may even time their migration to feed on migrating globe skimmer dragonflies in flight.

The pale blue waxy powder on some dragonflies' bodies, which rubs off during mating, is called what?

Where it is scraped away the darker cuticle shows through, leaving telltale marks on well-mated individuals.

In Hine's emerald dragonfly, where do females spend most of their time to avoid male harassment?

Males dominate the wetlands, so females visit them only to lay eggs or find mates; unwanted mating costs them foraging time.

Which parasitic flatworms use dragonfly nymphs as a stepping stone on their way to infecting frogs?

The larval cercariae leave a snail, enter the nymph and form a cyst that waits out its whole development until a frog eats it.

In the cyborg 'DragonflEye' project, how are steering commands delivered to the insect's nerve cord?

The dragonfly is genetically modified with light-sensitive neurons and carries a backpack of sensors, chip and solar panel over its thorax.