Tom Cruise in his role as Maverick in the movie Top Gun has nothing on the flying aces of the insect world: Dragonflies can beat their wings 20 to 45 times a second and work each of them separately, giving them incredible speed and agility. They can fly at bursts up to 35 miles per hour, turn 180 degrees in a flash, jet straight up or dive straight down. They can fly backward. They can briefly hover. What these insects want, they get! Targeted prey are doomed!
Dragonflies and damselflies are among the most beautiful and fascinating insects on earth. And they’ve been here a very, very long time — 285 million years, as some fossils have revealed. And there are fossils similar to dragonflies that go back to the Carboniferous Period 300 million years ago,¹ which is about 40 million years before the first dinosaurs. One of the fossils is over 28 inches (71 cm) from wingtip to wingtip! The largest of today’s dragonflies measure no more than 7.5 inches (19 cm).
Dragonflies and damselflies belong to the order Odonata (oh-doe-NAW-tuh), a name which comes from the Greek odonto for tooth and is a reference to their mouthparts, which are designed for chewing. There are 5,746² classified species of Odonata in the world, with roughly half being dragonflies and half being damselflies. Dragonflies and damselflies are found on all continents except Antarctica. About 450 Odonata species in 11 families inhabit North America; two-thirds of them are dragonflies.
Dragonflies handled carelessly may try to bite humans, and the larger ones may succeed in delivering a mild pinch. However, neither dragonflies nor damselflies have stingers, and they’re otherwise harmless to humans. They benefit us, in fact, by being formidable predators that consume prodigious amounts of nuisance insects like gnats and flies. Mosquitoes, too — giving rise to the name some people call them: mosquito hawks.
Dragonfly or damselfly?
Dragonflies and damselflies are in two separate suborders within Odonata. Damselflies are not female dragonflies. There are male and female dragonflies, as well damselflies of both sexes.The two groups differ in a few noticeable ways.
Dragonflies are in the suborder Anisoptera (an-iss-OP-ter-uh), which is from the Greek for “different wings,” because the hind wings are a bit larger than the forewings. Their abdomen is long, cylindrical and heavy-looking,
Damselflies are grouped in the suborder Zygoptera, which is from the Greek for “same wings.” Their wings are all the same size. Damselflies are usually smaller than dragonflies. Their abdomen is long, slender, cylindrical and delicate-looking.
(Note: To make the text a little less cumbersome, from hereon the word “odonata” will mean dragonflies and damselflies, except where differences between the two are noted.)
Adult odonates refuse to be ignored. First, there’s their conspicuously long body. Even the smallest North American species, the Citrine Forktail Damselfly (Ischnura hastata), about as thin as a toothpick, is around one inch (2.54 cm) long. The largest, the Giant Darner (Anax walsinghami), is 5 inches long (12.7 cm).
Odonates’ body colors draw the eye and refuse to let go. Females are usually less colorful than males, but both sexes scream, “look at me,” in their bright body colors — blue, lavender, green, bronze, scarlet, pink, red or yellow, sometimes even a blazing iridescent. They wear stripes and lines and bands or spots. Even those burdened with earth tones may be brightened with splotches of color.
Then there are the wings: wide and transparent, but often adorned with spots, bars or bands to add a jaunty look to their ensemble. Color defines their face, too. Some are white-faced or black, but many are green, red, yellow or blue.
The rest of their body is pretty spectacular, too, in its form and function. They have three body parts: head, thorax (middle section) and abdomen.
Odonates have a brain. It holds nerve cells which receive and send signals to the body. Attached to the head is a pair of inconspicuous short, thin antennae (an-TEN-ee). The mouthparts are large and take up most of the space not claimed by two huge eyes. Here, there’s a noticeable difference between dragonflies and damselflies. The dragonfly’s eyes are close together and often touch in the middle. Damselfly eyes are positioned wide apart, forming a bulge on each side of the head.
Odonates’ eyes reflect light in striking shades of bright blue, green, red, yellow-orange, brown or black. They aren’t merely pretty; they’re pretty perfect. They have compound eyes, each with 20,000 to 30,000 individual lenses (ommatidia) that together can see views from all angles. This gives them nearly 360 degrees of vision. (Just try sneaking up on one!) They also have three simple eyes, called ocelli (oh-CELL-ee), on their forehead, which are sensitive to light intensity. Watch a damselfly grooming its eyes and face
Odonates have two pairs of wings attached to their thorax, which is the middle section of their body. The dragonfly’s hind wings are slightly broader than the forewings, and damselfly wings are all the same size and narrow at the base. Odonates fly in a different style from other critters. Instead of a back-and-forth rowing-type movement, their wings move downward and backward and then upward and forwards.
All four wings usually have a “stigma,” which is a patch of color on the front edge. The wings are narrow and crisscrossed with veins that help give them strength. Each has its own muscles, allowing them to move independently and with unique agility. Dragonflies, while resting, hold their wings horizontal and at right angles to their body. Almost all damselflies, on the other hand, rest with their wings upright and together, in line with their body. The one exception is the Lestidae family, which spread their wings more like dragonflies.
Also attached to the thorax are three pairs of legs. They’re long and bristly, designed for holding onto large prey.
The abdomen is the back part of the odonate’s body. It is long and cylindrical and has 10 segments. It contains the digestive system, respiratory system, reproductive system, nerves and body fluids. More about insect anatomy
Males have four appendages at the tip of the abdomen. Two of them are claspers, used to hold onto the female during mating. The other two are sensory organs called cerci (SUR-sigh; singular, SUR-kus). The claspers are species specific. Females have two cerci, along with a conspicuous egg-laying organ called an ovipositor at the tip.
Odonates progress in stages from an egg to a nymph to an adult, in a process called incomplete metamorphosis (hemimetabolism). Their life involves water at all stages. First, they live in it as an egg and then as a nymph. As an adult, they spend their time near it.
Odonates are unique in that the male has two sets of sexual organs. It isn’t known why they have evolved this way, but their “primary organ” is on the ninth segment of their abdomen and their “secondary organ” is located on the underside of the second segment. This is important to know because it leads to a unique mating experience in the insect world.
Odonates mate from spring through summer and here’s how it goes: The male first grabs a female by her prothorax or the back of her head with his two claspers and holds on. Just before copulation, he curls his body so he can transfer a packet of sperm directly from his primary organ to his secondary one. The female, in turn, curves her body around until her sex organ comes in contact with his secondary organ. This forms a unique shape referred called the “wheel position,” but made more remarkable because it often looks more heart-shaped than round. Damselflies mate while perching, but dragonflies usually start mating while in flight and might then settle on a perch to complete the act.
Odonates sometimes stay attached after copulation in a “tandem position,” in which the male continues to clutch the female until she’s ready to deposit her eggs. It’s speculated that males do this to keep females from mating again, thereby ensuring their sperm fertilizes the eggs. (The male dragonfly is really competitive about this — he’s known to scoop out of the female’s organ any semen she may still be carrying from a previous sexual encounter!) Some species stay in tandem during the actual egg laying. With other species, the male merely guards the female against other males as she lays her eggs.
The female doesn’t necessarily lay her eggs immediately and may lay several thousand eggs before her life ends. Some species lay their eggs in water and others lay them in the stems of aquatic plants. Some eggs overwinter in water, but most species hatch out in one to eight weeks. As nymphs, they usually spend three or four weeks living in water, but some take longer.
Fertilized eggs are laid on aquatic plants or on the surface of water. When they hatch into nymphs (NIM-f), also called naiads (NAY-ud), they remain in the water.
Nymphs don’t have their parents’ beauty. In fact, they’re homely six-legged, oval-ish, wingless, brown or green things. Nature writer, Terry Krautwurst* describes them as armored-looking creatures that could have been designed by the creators of the movie Alien.
They’re certainly as lethal as the alien. They crawl around consuming everything they can catch. Not only that, but attached to their head is a rather creepy labium (lower lip) that functions something like a human arm with an “elbow” mid-way. At the tip are claws. This lip is kept folded underneath the head and thorax until suddenly, in a fraction of a second, faster than our eyes can see, it’s thrust forward and back, snatching a prey and pulling it to the nymph’s mouth. (This site has an animation of this, plus many interesting short videos of Odonata behavior.)
Dragonfly nymphs can be distinguished from damselflies by gills. A dragonfly’s gills are hidden in his rectum (yes, that’s correct). Damselfly nymphs, on the other hand, have three long, leaf-like gills extending from the tip of their abdomen.
The nymph, depending on the species, sheds its skin eight to 17 times to accommodate its growing body. With each molt, it shows a little more maturity, until finally, it’s ready to breathe air, its wings are eager to fly, and its sexual organ is ripe for mating. It crawls out of the water and clings tightly to a support — a plant stem, twig or rock — then molts for the last time.
Its skin splits down the back and, with great effort, the nymph begins working its way out. (You might find the discarded skin, called exuvia, still stuck to a plant stem long after it’s gone.)
If you’re watching, these are exciting minutes, waiting to see the color-drenched adult completely emerge. But, wait! This can’t be right: Its bright body colors aren’t there. It’s pale and unremarkable. And its wings, well, they’re short and limp, hanging down like a creature that’s beginning its terrestrial life in a state of despair. What went wrong?
Well, nothing! Like butterflies and moths, the adult’s wings won’t be functional until it pumps them full with fluid it’s holding in its body cavity. That will stretch those sad, empty bags out to their full size and gives them rigidity. Then they must dry.
This is a precarious, largely defenseless time for the new adult; it’s easy pickings for any predator passing by. After a brief drying time, it might be able to clumsily, slowly, lift itself skyward, but an escape would largely depend on luck. Once its wings are dry, however, it will sleekly lift itself skyward, looking for all the world like it’s done it a hundred times before. Now it’ll be much harder to catch.
Over the next few days, it’ll feed heavily and its body color will develop. Then, finally, dressed in its best, it’ll turn its mind to matters of courtship and mating. If it’s a territorial male, he’ll stalk out an area near water and defend it against entry by other males. Females, of course, are welcomed in. If it happens to be a non-territorial species, males may join several other males in pursuit of a single female. Many species of females stay away from breeding areas until they’re ready to mate or lay eggs.
Adults can live up to about two months or so, but probably average less because of predation by birds, fish, frogs, turtles, spiders and other insects. Some species, from their egg stage through adulthood, live several years, with most of it spent in the nymph stage. Adults don’t survive in winter. They spend their winter as eggs or nymphs in unfrozen water.
A few dragonfly species defy the weather by migrating southward as winter approaches. Some populations of the Common Green Darner, Anax junius, are known to migrate round trip. Radio-tagged individuals have been tracked flying to the northern U.S. and southern Canada in the spring after emerging in the southern U.S. Their offspring then made the return trip in the fall. Other migrating dragonflies are the Variegated Meadowhawk (Sympetrum corruptum), Black Saddlebags (Tramea lacerata), Wandering Glider (Pantala flavescens) and Spot-winged Glider (Pantala hymenaea). Dragonflies migrate like birds
Migratory dragonfly partnership
That dragonflies and damselflies are beautiful doesn’t mean they touch the insect world lightly. Both as nymphs and adults, they feed voraciously on anything they can catch and hang on to. As nymphs, they prey on anything smaller than themselves, such as worms, water beetles, mosquito larvae, small fish. Adults prey on mayflies, mosquitoes, gnats, other insects, even one of their own kind. There’s even the occasional story of a hummingbird being captured. Dragonflies usually hunt on the wing, snatching small prey directly into their mouth and the bigger prey with their legs before moving them to their mouth. Damselflies are more likely to feed on insects they find on vegetation.
Dragonflies and damselflies will visit saline water, but most are found wherever there’s freshwater — stream, pond, lake, river, bog, marsh, wetlands or small backyard water garden. Even springs and lakes in the desert have odonates. Some species prefer streams moving through coniferous or deciduous forests, while others choose habitats in grasslands or meadows. Some species like still or slow-moving water, while others like faster water. At any time of day, you’re likely to see one species or another. Damselflies usually fly close to the ground in their hunt for prey.
Some odonates like to perch on twigs or stalks that are sticking out of the water. Others prefer shady woodlands and still others like grassy areas. Like butterflies, Odonates must warm their wing muscles before taking flight. So, look for them to be perched motionless on stems and twigs, basking in the heat of the morning sun, or even shivering their wings to warm them up.
Odonates are especially vulnerable to predators while they’re in the egg or nymph stage. Once they become airborne they’re harder to catch. In the water, they’re preyed on by fish, water beetles, frogs and other carnivorous water species. Out of the water, they’re prey for whatever can catch them unaware, including songbirds, waterfowl, large insects (such as robber flies) and spiders.
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¹Mother Earth News Magazine, Sept. 8, 2006, pg. 27
²Source: ITIS Catalogue of the Odonata of the World, 2011