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Dragonflies are all-terrain insects: Lifeform of the week

Dragonflies are all-terrain insects that spend more of their lives underwater than in the air. They’re also agile, fast and fierce hunters. The majority of their head is taken up by their enormous eyes, and they eat nearly any smaller insect they can see.

An insect ready for action

There are around 7,000 species of dragonflies in the world. They’re found everywhere except Antarctica. Dragonflies live where there are water sources, such as lakes, ponds, swamps and rivers.

These insects are easy to recognize. They have six legs, double transparent wings (sometimes with colored spots) and a long, tubular body. They look a bit like tiny helicopters.

Dragonflies were one of the first insects to inhabit this planet, in the Carboniferous Period (359-299 million years ago). Back then, dragonflies were much bigger. The oldest recorded fossil is around 300 million years old. Some ancient dragonflies had wingspans of up to 2 feet (0.6 meter).

These insects evolved to be smaller, but also faster, more agile and with impressive vision.

Closeup of head and midsection of an insect. It has huge blue compound eyes and 4 wide open, transparent wings.
There are around 7,000 species of dragonflies in the world. They are fast, agile and voracious hunters. Image via Arie Versluis/ Pexels.

Dragonflies in flight

Unlike other insects, dragonflies are unable to fold their wings over their torso, so they always have them fully extended. Damselflies look very similar, but these creatures fold their wings over their bodies instead of spreading them out to the sides when at rest.

Dragonflies have two pairs of wings with muscles on the thorax (middle section) that work independently, allowing them to change the angle of each. This enables them to fly in any direction, even backward. Hummingbirds, which are the smallest birds in the world, also have this ability.

In addition, dragonflies can hover in one place for more than a minute. They are not only agile, but they’re also fast. Their elongated and thin bodies allow them to fly very quickly. Some species can reach 56 miles per hour (90 kph).

They can also travel great distances. Some species migrate in groups and cover distances of more than 9,000 miles (15,000 km). There are few species in the animal kingdom that can match the dragonfly in its spectacular flight ability.

Long, thin insect with 4 yellow and black striped wings outspread. It is perched on a twig.
Dragonflies have 2 pairs of wings with muscles on the thorax (midsection) that work independently, allowing them to fly in any direction. Some species can reach 56 miles per hour (90 kph). Image via Mel Stratton/ Pexels.

A terrifying predator

Dragonflies are absolutely terrifying to smaller insects. They attack their prey from the air with calculated aerial ambushes. And they can measure the speed and trajectory of a target and adjust their flight to intercept it. They are so skilled that they have a success rate of up to 95%. Dragonflies are kind of like flying Rambos.

When hunting, dragonflies capture their prey with their legs and tear off their wings with their sharp jaws so they cannot escape. The anatomy of dragonflies’ legs allows them to catch prey in flight, but not walk with them. But don’t worry, humans are safe from dragonflies. Their jaws are specially designed for chewing, but not for stinging.

In fact, if you hate mosquitoes, then dragonflies will be your best friends, since they help us control these pests. In a single day, dragonflies can consume up to 14% of their body weight. They feed on anything edible that comes within their sight … There’s a reason it’s one of the deadliest predators on the planet.

Closeup of the orange midsection, head, legs and wings of an insect. It has enormous red and green eyes.
Dragonflies are absolutely terrifying to smaller insects. They feed on anything edible that comes within their sight and have a success rate of up to 95% when hunting. Image via Oktavianus Mulyadi/ Unsplash.

Look at those big eyes

Dragonflies have some of the largest eyes and most precise vision of all insects. The head is mainly made up of two enormous compound eyes, which meet at the back of the head. Thanks to this, the dragonfly can see 360 degrees of its surroundings without having to turn its head in the slightest.

These compound eyes contain 30,000 small hexagonal panels. Each has its own retina and lens, allowing a dragonfly to see its prey from a distance of up to 40 feet (12 m). Dragonflies also have three simple eyes with simple lenses.

Closeup of the head of a yellow insect with huge orange and yellow eyes made up of thousands of tiny cylinders.
Dragonflies have 2 compound eyes and 3 simple eyes. They can see 360 degrees of their surroundings without having to turn their head. Image via Saradasish Pradhan/ Unsplash.

The underwater life of dragonflies

The life cycle of the dragonfly begins when its parents mate, which happens in the air or on land. The female then deposits her eggs in or very close to the water, usually on aquatic plants such as water lilies.

When the eggs hatch, they release the nymphs, which are their underwater form. In this phase, they feed mainly on the larvae of other insects or even tadpoles and fish. As you can see, the dragonfly is already voracious from a very young age.

Once ready for metamorphosis, the nymph emerges from the water clinging to stems, branches and other exposed surfaces, and begins breathing air. Then, the larva’s tough skin opens and the adult dragonfly emerges, ready for an aerial life.

The outer skin the nymph leaves behind, called exuvia, can be found attached to stems and branches for a long time after the dragonfly becomes an adult.

The curious thing is that dragonflies live much longer underwater than out of it. Normally, large nymphs live in water for about five years, and small ones from a few months to around three years. However, they only live a couple of months out of water.

A group of long-bodied blue insects with transparent wings touching a water surface with their tails.
Before becoming the insects we all know, dragonflies live underwater and look very different from their adult form. These are damselflies laying their eggs in the water. Damselflies look very similar to dragonflies, but these creatures fold their wings over their bodies instead of spreading them out to the sides when at rest. Image via Clément Falize/ Unsplash.

How do dragonflies breathe?

Since these insects live both under and above water, their respiratory system changes. During their phase as nymphs, they breathe through gills at the end of their body, which can be internal or external.

The dragonfly nymph carries the water it takes to the end of its abdomen, where gas exchange takes place. This process allows the nymph to obtain oxygen to breathe. Furthermore, by expelling water, it is capable of propelling itself like a missile, facilitating its ability to move quickly through water.

Exposure to air leads the nymph to initiate respiration. The skin opens at a weak point behind the head and the adult dragonfly crawls out of its larval skin.

Like all insects, dragonflies don’t have lungs, but rather they breathe with tracheae, air tubes that go to every part of the insect’s body. The openings of the tracheae, called spiracles, are in the thorax (midsection) and abdomen.

Dark insect underwater. It has 6 legs, 2 small antennae and a long, heavy body that ends in 3 points.
As nymphs, dragonflies breathe through gills. When adults, they breathe through spiracles and tracheae. Image via Totodu74/ Wikipedia (public domain).

My dad found a very strange insect swimming underwater in our water lily pond, and then we received the image below at EarthSky Community Photos. All the signs were there for me to write this article …

Small, round, dark insect perched on a blade of grass.
View at EarthSky Community Photos. | Our friend Randy Strauss from Walnut Creek Lake, Nebraska, captured this image of a dragonfly nymph on July 24, 2024. He wrote: “I was stumped on what this guy was until a very kind university entomologist identified it for me. It is a dragonfly completing its nymphal stage of life. It had been living in the water and had climbed up onto a vertical surface where it will emerge from its nymphal skin, unfold its wings and appear as a recognizable dragonfly in the teneral stage of its life.” Thank you!

Dragonflies in Japan

The Japanese have great appreciation for dragonflies. In the past, people created designs with this insect, which decorated armor, helmets and weaponry of samurai warriors. Dragonflies were a symbol of agility, power and victory.

Brown metal Japanese helmet. It has a big dragonfly, with a wingspread much wider than the helmet, mounted on top.
Dragonflies were a favorite emblem of the samurai. It was respected for its hunting technique: flying directly toward its prey, never wavering from its path. Image via MET museum (public domain).

Nowadays, excursions are organized to appreciate and study them in their natural environment.

Dragonflies: Head of an insect with huge green and brown compound eyes covered in tiny drops of water.
What a wonderful closeup of dew on huge dragonfly eyes. Image via Egor Kamelev/ Pexels.

EarthSky Community Photos

Long, thin, brown insect with 4 transparent wings with 3 black spots on the leading edge.
View at EarthSky Community Photos. | Lorraine Boyd from Delmar, New York, photographed this dragonfly and wrote: “An interesting fact is that the dragonflies are among the world’s best hunters with a success rate of 95%.” Aren’t they amazing? Thank you, Lorraine.
Long, thin insect perched on a twig. It has a round head and transparent wings with wide, dark brown stripes.
View at EarthSky Community Photos. | Steve Price from Kidney Pond, South Jordan, wrote: “Dragonflies are quite territorial. As a result of that, they tend to land on the very same twig, reed or stick every time they take a break from aerial hunting. So I only had to observe a specific dragonfly and wait until it perched nearby. Then I would slowly approach hoping not to scare it away and take the pics. If they do fly off, I just stand there very still up to 5 minutes and sure enough they will land on the very same stick. Patience and a little stealth craft wins the day.” That’s very good advice. Thanks!
Long, thin, light blue insect with 4 outspread transparent wings, perched on a wire.
View at EarthSky Community Photos. | Barry Medlin from Georgia wrote: “While walking along the boardwalk at Moody AFB wetlands area, I spotted this Eastern pondhawk (Erythemis simplicicollis) resting on a fence. Lots of different dragonflies in this area, but were too far away for me to get a good shot. This one was the exception!” Very nice pic! Thank you.

More EarthSky Community Photos

Insect with big green midsection and long black abdomen, perched on a rock.
View at EarthSky Community Photos. | Jane T from Hong Kong, China, wrote: “This green skimmer dragonfly (Orthetrum sabina), with a military-patterned thorax and an artillery-style abdomen or ‘tail’, could almost be a CGI creation from a science fiction movie.” Indeed! Thank you, Jane.
Insect with red stripes across its thin abdomen. The rest is brown and it has outspread transparent wings.
View at EarthSky Community Photos. | Cecille Kennedy took this photo from Oregon on September 1, 2023, and wrote: “I read that during some events, they are seen in huge numbers in multiple places, sometimes swirling together in giant formations. Last month they were observed making their way along the north Oregon coast in a migration run which takes place when there’s a lot of east winds coming in. No one seems to know where exactly they’re coming from and certainly where they’re going. They remain a mystery on the Oregon and Washington Coast.” Thank you!
A long, thin insect in flight. It has 4 outstretched wings making an X.
View at EarthSky Community Photos. | Randy Strauss from Walnut Creek Lake, Nebraska, photographed this flying dragonfly and wrote: “To capture a dragonfly in flight I take around a hundred exposures and then sift through them, looking for the one or two that are in focus; these guys are amazingly fast and change direction in a fraction of a second.” They are! Very nice photo. Thank you.

Bottom line: Dragonflies are fierce hunters with a very high success rate. They are agile and fast. And they live underwater much longer than in the air.

Read more: The praying mantis is a predator: Lifeform of the week

Read more: Ants, little but tough: Lifeform of the week

Posted 
September 9, 2024
 in 
Earth

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