Common Green Darner dragonfly Anax junius in mid-flight. Photograph taken by the author. Copyright Now I Wonder.

Are Dragonflies Actually Flies? Complete Guide To The Answer

Have you ever wondered if dragonflies are actually flies? After all, the word “fly” is literally included in the name “dragonfly”. And if not, why call them dragonflies? If youโ€™re wondering this too, this post will help.

Dragonflies and flies are unrelated insects. Dragonflies are much larger than flies and have four wings compared to flies which have only two wings. Flies undergo complete metamorphosis while dragonflies undergo incomplete metamorphosis. They live in different habitats and have different lifestyles.

Dragonflies and flies are superbly adapted to their respective niches in the natural world. Each would starve to death if forced to live the otherโ€™s lifestyle.

A common whitetail male dragonfly sunning on a rock with wings spread. White body, clear wings with dark brown splotches in middle of each of four horizontally held wings.
This male common whitetail skimmer dragonfly<em> Libellula lydia<em> suns himself on a rock beside a pond Photograph taken by the author Copyright Now I Wonder
Unknown species of fly (possibly a type of flesh fly in Family Sarcophagidae) perched on leaf from above.
Unknown species of fly perched on leaf from above Possibly a type of flesh fly in family Sarcophagidae Photograph taken by the author Copyright Now I Wonder

Overview of the differences between dragonflies and flies

Below is a table that summarizes several important differences between the two insect Orders. Because the terms โ€œdragonflyโ€ and โ€œflyโ€ both cover a huge and diverse variety of creatures, Iโ€™ve narrowed each insect type to an example species to illustrate the differences.ย 

DragonfliesFlies
OrderOdonata (oh-doh-nah-tah) – means “toothed”Diptera (dip-tair-ah) – means “two-wings”
Approximate number of worldwide identified species5,600150,000
Size range1.4 – 3.7 inches (3.6 – 9.4 cm)0.28 – 0.31 inches (0.7 – 0.8 cm)
Body shapeLong, thin body with large head and thorax and elongated abdomen tapering to a pointShort and compact, thorax and abdomen about the same length
Wing configurationTwo (2) pairs of large, elongated membranous wings.

Wing pairs are similarly sized.
Wings are held at approximately 90 degrees to the long axis of the body at rest, within the same plane.

All wings contribute to powered flight and maneuverability.
One (1) pair of tapered membranous wings.
Hind wing pair are vestigial sensory organs called โ€œhalteresโ€.

Wings are held at approximately 30 degrees to the long axis of the body at rest, within the same plane.

Only the fore wings contribute to powered flight. Halteres stabilize the body and send sensory information about air currents and speed during flight. 
Mouth structureChewingMostly sucking, sponging and lapping.
Some species chewing.
Leg structurePerching, graspingWalking, standing
ColorsSpecies and sex dependent.
Can be bright blue, green, yellow, bright red, brown and black.
Wings can be transparent or translucent or display dark patches.
Species dependent.
Thorax is striped with black and gray, abdomen is brown. Wings are translucent.
Some species can be iridescent green or blue.
Common habitatSpecialist: Lakes, ponds, quiet portions of rivers with heavy vegetationGeneralist: All areas associated with humans and human-raised livestock (โ€œsynanthropicโ€)
LifestylePredatorScavenger
DevelopmentIncomplete metamorphosis (“hemimetabolism”)Complete metamorphosis (“holometabolism”)
Species exampleLibellula vibrans (“Great Blue Skimmer”)
Musca domestica (โ€œHouse flyโ€)
Overview of differences at the Order level.

Dragonflies and flies have different body shapes

A dragonflyโ€™s body is very long and thin, with a large thorax (where the legs and wings attach) and a narrow, extended abdomen. A fly’s body is much shorter and stockier overall.

Eastern Amberwing dragonfly (Perithemis tenera) perched on grass. Photograph by author. Copyright Now I Wonder.
An Eastern Amberwing dragonfly <em>Perithemis tenera<em> perched on grass Photograph by author Copyright Now I Wonder
Unknown species of fly (possibly a type of flesh fly in Family Sarcophagidae) perched on leaf from the front.
Unknown species of fly possibly a type of flesh fly in family Sarcophagidae Photograph taken by the author Copyright Now I Wonder

Dragonflies and flies are different sizes

They are also very different sizes. Dragonflies are huge compared to flies; the Great Blue Skimmer is about 8 times bigger than a House Fly. In fact, dragonflies may be as big and heavy as an insect can become and still fly in todayโ€™s atmosphere.

Dragonflies and flies are different colors

Dragonflies come in a dazzling array of colors, including brilliant greens, browns, blues and reds. Male Great Blue Skimmer dragonflies are a striking pale blue with bluish-green eyes, while females are a reddish brown with a black stripe down the abdomen.

House Flies, on the other hand, are mostly black and gray, although they can appear tinged with green in certain lights. Other fly species may show iridescent green and blue coloration but in general, flies are much duller.

Dragonflies and flies have different wing configurations

After size, the number of wings and their positioning probably stand out as the most visible differences between the two types of insects. All dragonflies have four wings; all flies have only two.

Dragonflies hold their wings straight out horizontally, which gives them a distinctive t-shaped silhouette. Flies have only two wings which lie on top of their thorax and extend slightly out to the side in a triangular silhouette.

Dragonflies and flies fly differently

The wing differences go beyond the cosmetic; the two types of insects actually fly differently.

The Great Blue Skimmer – like all dragonflies – flaps its front wings independently from its hind wings, which lets each pair catch undisturbed air.

Additionally, the dragonfly twists each wing on the down stroke of each flap, โ€œcreating miniature whirlwinds that allow air to move much faster over the upper wing surface, reducing the air pressure there and greatly increasing lift.โ€ (Imes 1992, 68)

This is a unique mode of flight in the living world and has been studied extensively. The House Fly flies in a more usual manner, flapping both wings at the same time to generate lift.

Dragonflies are fighter pilots; flies are acrobats

Both dragonflies and flies are superb aerialists and can hover, fly backwards and change directions in midair faster than the human eye can follow.

But the House Fly can perform an acrobatic trick that the Great Blue Skimmer canโ€™t – it can turn itself upside down in midair.

A House Fly beats its wings much faster than a dragonfly does – approximately 1000 beats per second versus a dragonflyโ€™s 20-40 (Tenneson 2009). When combined with lightning fast information about air currents and the insectโ€™s position in space supplied by the halteres, this fast wing speed allows a House Fly to flip itself over completely in mid-air without falling from the sky.

Flies usually perform this maneuver to land upside down on a surface. Special pads covered in sticky secretions on their feet grip their landing surfaces. These adaptations allow House Flies to cling securely to nearly any surface.

By contrast, dragonflies must stay upright.

Dragonflies may not be able to turn somersaults on the wing but they are speed demons in the air. Dragonflies can zoom around their territories at speeds up to 35 miles per hour (56 kilometers per hour) (Imes 1992, 68).

The House Fly flies at a comparatively pokey average speed of about 4.5 miles per hour (7.2 kilometers per hour) (Dahlem 2009).

Dragonflies and flies have different mouths

Skilled predators, dragonflies hunt on the wing, snatching flying insects out of the air. Their jaws (or โ€œmandiblesโ€) are large, serrated and powered by strong muscles perfect for slicing through the hard exoskeletons of their insect prey.

On the other hand, House Flies are scavengers that feed on decaying organic matter by lapping up liquid. They have no need for strong jaws like the dragonflies so their mouths have developed sponging mouth parts instead.

Dragonflies perch; flies walk

Both dragonflies and house flies can perch on their hind-most four legs and use their front legs to perform various tasks. Dragonflies use their front legs to hold and manipulate prey, whereas house flies use them to clean dust and debris off their body bristles.

But flies and dragonflies move very differently when grounded; flies can move easily across a surface while dragonflies have difficulty moving at all.

The legs on all dragonfly species crowd together towards the front of their thoraxes. This adaptation allows space within their thoraxes for the huge flight muscles that power the dragonflies’ long, narrow wings.

The positioning of their legs allow dragonflies to swing all six legs forward during attack on prey, scoop the insects out of the air and grip them until the dragonflies can grab them with their jaws. But this clustered arrangement limits the mobility of its legs when not in the air and prevents dragonflies from walking easily.

For more information, check out this Now I Wonder post “Can dragonflies walk?“.

By contrast, house flies walk easily on widely spaced legs adapted for moving around on foot. A House Fly has two choices for moving from one location to another; it can either walk or fly. A dragonfly doesn’t have this choice; a dragonfly basically has to fly to get anywhere at all.

A blue dasher dragonfly (Pachydiplax longipennis) perched on the tip of a twig. This skimmer dragonfly has a pale blue body, clear wings, and bright green eyes.
This Blue Dasher dragonfly <em>Pachydiplax longipennis<em> is a member of the skimmer family Libellulidae Photograph taken by the author Copyright Now I Wonder

Complete versus incomplete metamorphosis

Dragonflies undergo incomplete metamorphosis, which means that they share some of the same physical structures at all life stages. Immature dragonflies have six legs, the same three body segments and very large eyes as the adults, and wing buds. While different in many ways, you can recognize these immature insects as “dragonflies” if you know what to look for.

But flies undergo complete metamorphosis. This means that immature flies look completely different from adults. Known as maggots, larval flies look like worms, with soft, unsegmented, legless and headless bodies. Identifying a maggot as a “fly” based on its appearance is difficult.

Dragonflies are good neighbors; flies cause problems

Dragonflies and flies live very different lifestyles.

Dragonflies live near quiet, fresh water which supports abundant populations of flying insects. They chase these insects down for food and donโ€™t bother people. They cause cause no harm to humans. In fact, their appetite for eating huge enormous numbers of other insects benefits humanity since many of the species they feed upon do damage humans. For example, flies.

Flies live worldwide in all habitats because their food is easy to come by. As scavengers, they need only to locate sources of their preferred food, land, and feast.

Unfortunately, flies are not picky. They make no distinction between landing on a rotting rat as your picnic lunch and alternate happily between the two as needed.

Despite being admirable in many respects, flies can and do hurt thousands of people every year. Some species, like the House Fly, transmit diseases with their sticky feet. They land and walk around on decaying organic matter. Dangerous microorganisms cling to their sticky feet. The flies then transport these microorganisms to other locations, such as onto human food or even onto humans directly.

Other fly species such as black flies, horse flies, and deer flies evolved biting mouth parts, which they use on humans. And of course, mosquitoes- which are also flies- infect millions of humans every year with various deadly diseases, such as malaria, dengue, encephalitis, and yellow fever.

Different insects; fascinating abilities

Dragonflies and flies are totally different creatures who have different skills, behaviors and lives. But they share one very important trait – they are both fascinating residents of the natural world.

References

Dahlem, Gregory A. “House Fly.” In Encyclopedia of Insects, edited by Vincent H. Resh, and Ring T. Carde. 2nd ed. Elsevier Science & Technology, 2009.

Imes, Rick. 1992. The Practical Entomologist. London: Quarto Publishing.

Meyer, John. North Carolina State University, NC State General Entomology, https://projects.ncsu.edu/cals/course/ent425/library/compendium/odonata.html

Tennessen, K. J. “Odonata.” In Encyclopedia of Insects, edited by Vincent H. Resh, and Ring T. Carde. 2nd ed. Elsevier Science & Technology, 2009.

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Christine
Christine is the creator and author of NowIWonder.com, a website dedicated to the animals and plants that share our world, and the science that helps us understand them. Inspired by lifelong exploration and learning, Christine loves to share her knowledge with others who want to connect with wild faces and wild spaces.

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