Written by Ann Cooper
- How many different species of dragonflies might I find in Arizona? How many might I find in the United States?
- Do dragonflies sting or bite?
- What are the smallest and largest dragonflies in Arizona?
- Where should I look for dragonflies?
- Are dragonflies attracted to lights?
- When should I look for dragonflies?
- What do dragonflies eat and how do they catch their food?
- How long do dragonflies live?
- What happens to dragonflies in winter?
- How good is dragonfly vision?
- What enables dragonflies to be such agile fliers?
- How long have odonates been around?
- Do dragonflies have territories?
- Do male and female dragonflies of the same species look alike?
- What are dragonflies doing when you see two linked together?
- What’s going on when a dragonfly perches with its abdomen pointed skywards (obelisk position)?
How many different species of dragonflies might I find in Arizona? How many might I find in the United States?
Dragonflies thrive in warm climates, with their greatest diversity in the tropics, so it’s a natural that a comparatively large number of dragonfly species occur in Arizona. Almost one hundred and forty species have been found here—so far.
The numbers are not fixed. At any time, new species may travel north from Mexico to establish populations here. In fact, three of the counties with a high number of species—Cochise, Pima, and Santa Cruz—lie along the border.
The United States as a whole has over four hundred and seventy-five species, a number also subject to change.
Please note, the number of species recorded in any location depends significantly on the number of people looking! You, too, could add to collective knowledge with your observations, especially in the less-surveyed counties.
Dragonflies do not sting. They don’t have venom or defensive chemicals of any kind. The traditional names given to dragonflies in some parts of the world, names like Horse Stinger, Devil’s Needle, or Snake Killer, are fun folklore only.
Large dragonflies, both larvae and adults, have strong jaws with which they crunch up their prey. Dragonflies are capable of biting, but the chances of you being bitten are slim to none unless you regularly handle them. If a dragonfly latched on to your skin and bit down hard, you’d probably feel a sharp pinch, but suffer no lasting damage
The term “dragonfly” is often used to include both dragonflies and damselflies. With this in mind, Arizona’s smallest dragonfly is a tiny and dainty damselfly, the Citrine Forktail (Ischnura hastata). Its body from tip to tail is from 21-27 mm (0.83-1.06 inch)—roughly the length of a quarter--and its wingspan is about 9-15 mm (0.35-0.06 inch). The straw-colored males and the dull blue females seem to disappear with ease among wispy, dry grasses.
The largest dragonfly in the state is aptly called the Giant Darner (Anax walsinghami). It is 88-98 mm long (3.5-3.86 inch) and has a 56-60mm (2.2-2.36 inch) wingspan. Its long abdomen appears slender in flight—the way you will most often see this stunning insect. The Giant Darner spends much time patrolling up and down a chosen stretch of stream, rarely appearing to rest.
Dragonflies split their lives between two very different habitats. As larvae they need water (or very wet places) to live. As adults they are masters of air and land . . . but still depend on wetlands to lay their eggs and complete the lifecycle. Because of their close dependence on water, the best place to look for dragonflies is close to water—ponds, lakes, streams, arroyos, springs, cienagas, ditches, irrigation channels, puddles, city parks, golf courses, garden water features, puddles, even sewage-treatment plants.
But don’t stop looking there. You can also see dragonflies far from water. They may gather in feeding swarms when there’s a good hatch of edible insects. They may hilltop (like butterflies), or appear in places far from water when they are migrating.
Visit our Locations page for suggestions on specific geographical areas to watch dragonflies.
Dragonflies do not appear to be attracted to lights as such. But some species seem to take advantage of insects that are attracted to lights. It’s like a dragonfly fast food outlet. Look for dragonflies in places that keep the lights burning all the time, such as gas stations and well-lit highway intersections.
Arizona is fortunate to have dragonflies flying year-round, but the number of species and of individuals to be seen hit the high point in the warmest months.
Dragonflies don’t keep a steady body temperature as we do. They regulate their body temperature by behavior, basking in sun to warm their flight muscles, or changing their body-posture or retreating to shade to keep cool. They are most active when it is sunny, but not too hot. Their activity level drops under heavy cloud cover. They avoid rain and high winds.
You don’t need to start looking for dragonflies at the crack of dawn; they’re inactive then. But if you can find them early in the day, you may enjoy a rare chance to watch and photograph dragonflies and damselflies before they warm up and begin to move fast. In midsummer, there is often a lull in activity in the heat of the afternoon, so you might consider taking a siesta too!
Whether as larvae in the water or adults in the air, dragonflies are fierce predators, catching and eating other animals. They will take any meat they can catch. Larvae lie in wait, or stalk their prey stealthily. They have a unique hinged lower mouthpart that shoots out (like lazy-tongues) to capture prey. They eat all kinds of pond creatures, including fly larvae, mosquitos, small fish, tadpoles, even larvae of other dragonflies. It’s known that larvae may eat their own kind— cannibalism.
Adult dragonflies pursue prey in the air, and often eat as they fly unless the prey is too large. The menu might include mosquitos, flies, moths, butterflies, beetles, other dragonflies and damselflies, and more. They catch prey with the help of their spiny legs that function like baskets. Damselflies are gleaners, picking tiny insects and other minute arthropods off plant stems and leaves. Their action is delicate and the toothpick-like insects seem to float around vegetation without apparent effort.
When people ask this question, they usually want to know how long dragonflies live as adults. The answer is, for most species, anywhere from a few days to about six weeks or so—if they are lucky. There are many hazards that may prevent a dragonfly from reaching old age. They may become meals for other predators such as birds, turtles, or fish (especially when dragonflies are distracted at the pond or river during mating or laying eggs).
Before they emerge as adults, dragonflies have already spent significant time in the water, first as eggs and then as larvae. If you add this into their life span, the answer may be a few months to more than a year.
Most adult dragonflies that you see in summer and fall will reach their natural life span and die before winter. Some species have flight periods that cover the whole year, but the individuals may belong to different generations.
Some dragonflies migrate south in winter, in much the same way that Monarch butterflies do. The same individuals probably don’t make the round trip, but details of these migrations are not yet well understood. Among the species known to migrate are Common Green Darner (Anax junius), Wandering Glider (Pantala flavescens) and Spot-winged Glider (Pantala hymenaea), Variegated Meadowhawk (Sympetrum corruptum) and Black Saddlebags (Tramea lacerata). They migrate by day and cold weather probably prompts their southward journey.
Adult dragonflies do not hibernate. Larval dragonflies and dragonfly eggs can temporarily halt their development during winter, a process called diapause, which could be loosely thought of as hibernation. Some species time the end of diapause so a large number of the same species emerge at the same time. That way, a few are taken by predators, but the rest survive—a case of safety in numbers?
As anyone who has tried to sneak up on a dragonfly will know, dragonflies have superb vision. Their huge compound eyes take up almost the entire head. They have a near-360 degree view of their surroundings and approaching predators—or mates, or rivals—and are spectacularly aware of movement. (If you want to snap that photographic masterpiece, creep slowly from directly behind the dragonfly and keep a low profile.)
Each compound eye is made up of thousands of individual ommatidia, or visual units. (The often-cited number is 30,000, but who is counting?) Each ommatidium is covered by a transparent cornea which gives the eye surface a honeycomb appearance. Each ommatidium creates its own image, which the brain integrates into an overall picture. Dragonflies see a full spectrum of color—ultra violet included—and can see polarized light, which may help them find bodies of water of appropriate depth and substrate to suit their breeding needs.
Watch a dragonfly and you are bound to marvel at its aerial acrobatics: up, down, turn, twist, hover, land and zoom off again, even fly backwards or upside down for a short time.
One reason for this versatility is that a dragonfly’s four wings work independently of one another. Each wing has its own muscles to power it. (Contrast this with other insects such as butterflies, also with four wings, whose flight muscles work to deform the entire thorax to produce the up and down motion of the four wings working in sync.) As a result of its independent musculature, the dragonfly is capable of quick turns and changes in direction, but also of working the wings together when necessary to give it an extra burst of lift.
The structure of the thin, see-through wings is a second marvel. The wings are surprisingly strong for all they look so frail. They are crinkled, not flat, for strength. The node, or notch, in the wing’s leading edge allows for a wing twist that adjusts the flight aerodynamics. The pterostigma, or colored or thickened cell near the tip of each wing, may help wing stability especially in gliding. And although dragonflies cannot mend or regrow damaged wings, they are still capable of flight when their wings have become tattered and worn, or even when part, or all, of a wing is missing.
We know, from the fossil record, that dragonflies have been around for about 325 million years, give or take. If you were to examine these fossils, you’d see wing venation that’s recognizable as a dragonfly, although the earliest wings lacked an apparent nodus (notch at the leading edge of the wing) and pterostigma.
An extinct genus, the Meganeura from the Upper Carboniferous era, had wingspans up to 65 cm (25.6 inches) or more—equivalent to the wingspan of a present day magpie. There’s been much speculation on why these insects were able to grow so large, when the size of modern insects is limited by their body functions (having exoskeletons, and breathing by diffusion of oxygen into the body interior). One hypothesis postulates that ancient odonates grew larger because there was more oxygen in the air that was available for diffusion into the insect’s body. However, we do not know for sure and so the jury is still out.
Have you ever wondered why you see more male than female dragonflies around a pond or along a river? The reason is that male dragonflies come to the water to stake out territories in what they deem to be good potential breeding and egg-laying sites, and wait there, defending their stretch of real estate until the females arrive. The females usually don’t turn up at these rendezvous points until they are mature enough to mate. Before then, they hang out in meadows or treetops a distance away from the water.
Male dragonflies defend their territories in different ways. Many of the skimmers, such as the Widow Skimmer (Libellula luctuosa) perch on a central twig or reed from which they can survey “their” section of bank. From there, they’ll dart out to repel rivals (or grab a likely mate) before returning to the same, or nearby, perch again. Some, such as the darners or river cruisers, may patrol up and down a fairly long lake shore or stretch of river, chasing off intruders. The tiny amberwings, wasp-mimics, may defend a small patch of floating algae only a few feet across. But the mission is always the same: to effectively proclaim ownership of good breeding habitat. In addition, territories are not only places but also time-slots: different species often claim a same area at slightly different times of day.
Although some dragonflies look superficially like their counterparts of the opposite sex—especially when you see them only fleetingly or in flight—males and females differ anatomically. Males have secondary sexual organs beneath the second and third segment of the abdomen (S2-3) where they lodge their sperm ready for a female to collect during copulation. They also have equipment here that enables them to remove from the paired-up female any sperm from a previous mating, making sure of their paternity. In side view, you can see the male’s bulge on S2-3. In addition, his abdominal appendages, which he uses to clamp on to the female’s head, are diagnostic in shape.
Females lack this S2-3 apparatus. They tend to have overall slightly stockier abdomens, sometimes slightly swollen at the end, and from the side you may see the ovipositor, or egg-laying tube, protruding from below the abdomen end. Note that in one group of dragonflies, the clubtails, males also tend to have enlarged abdomen tips, but this is related to the anatomy of their terminal clasping appendages.
Apart from differences in anatomy, male and female dragonflies may also differ—sometimes quite drastically—in coloration. For example, the Flame Skimmer (Libellula saturata) female is buffy-yellow whereas the male is an eye-catching orange. To add to the potential confusion, many damselfly species have more than one color form of female. In these species, females may be either somewhat like the male in coloring (but with different anatomy) or radically different—orange rather than blue predominating, perhaps, like the Rambur’s Forktail (Ischnura ramburii.)
Three other confusing situations are worth mentioning: immature male dragonflies may have female-like coloration until they attain mature color; older dragonflies make have obscured patterns because their bodies become blueish or white (pruinose) with a waxy coating; and color can be affected by temperature (duller in the cold).
When you see two dragonflies “in tandem”, where the male has grabbed the back of the female’s head and they are either flying of perching in this attached position, they could be about to mate, or just have finished mating, or be about to lay eggs with the male maintaining contact to guard the female from potential interference. For example, the male Common Green Darner (Anax junius) frequently contact-guards his female as she injects eggs into a floating plant stem.
When you see two dragonflies in a roughly heart-shaped configuration, with the male holding the female’s head and the female reaching her tail-tip beneath the male’s abdomen where his secondary sex organs lie, they are in copula, or mating. This is often referred to as the “wheel” position. Many species perch during this time, but others keep flying. The wheel may hold from seconds to an hour or more.
(Obelisk: an upright, tapering stone pillar with a pyramidal tip, erected as a monument.)
A dragonfly perches in the obelisk position, with its abdomen sharply angled upwards to the sun, to minimize the amount of sunlight falling on its body surface. It will do this to reduce the chance of overheating in hot and sunny condition. Its next strategy in extreme heat may be to retreat to the shade. Obelisking is the opposite of basking, when the dragonfly rests flat on a sun-soaked rock, road bed, or dirt patch, to warm up its muscles ready for flight.
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Want to learn more fascinating facts about dragonflies? Looking for expert answers to your questions about them? If so, check out Dragonflies: Q&A Guide, by Ann Cooper.
Dragonflies: Q&A Guide
By Ann Cooper