Dragonflies

Four years ago, on July 31, 2016, while working at my computer in my home office I noticed some dragonfly love happening under the eave just outside my window. Near sunset. How romantic!

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At first, I didn’t realize what I was seeing. It was easy to identify them as dragonflies – the double sets of wings a sure giveaway – but they were connected like two circus contortionists hanging from a rope. They didn’t appear angry or distressed. So, what else could they be doing, other than mating?

I didn’t know for sure, though. Curious, I googled “How do dragonflies mate?” I found this wonderfully cheeky explanation on About.com: Dragonfly sex is a rough and tumble affair. If you’ve ever seen a pair of mating dragonflies in the throes of passion, you know that their sexual coupling requires the flexibility and acrobatic skill of a Cirque de Soleil performer. Females get bitten, males get scratched, and sperm winds up everywhere. These strange mating habits have survived millions of years of evolution, so the dragonflies must know what they’re doing, right?

Who knew? Online photos better than the one I took that day show mating dragonflies making the shape of a heart. Awwww. Apparently the two I saw were still practicing, not quite achieving the heart shape. Or maybe my angle was bad.

I posted my photo of the two dragonflies in flegrante to my Facebook page. A friend commented with a photo of a column from his local Arizona newspaper (written a year earlier).

Another cheeky answer to an earnest question about dragonfly mating habits.

Now that I know more about dragonfly mating, if I got such a letter today, I’d advise the writer to avoid swallowing the water while swimming in their pool during dragonfly mating season, given the bits about “sperm winds up everywhere” and “indirect insemination” (see below, the last paragraph under Fun Facts).

On July 31st of this year, my 2016 photo popped up in my Facebook memories, roughly a week after I saw gorgeous photos of dragonflies on another blogger’s site. I was inspired to do some research and create this post.

Dragonfly Fun Facts

Here for your consideration are some interesting facts about dragonflies culled from a Smithsonian magazine article and Wikipedia.

Some of the first winged insects to evolve some 300 million years ago, today’s dragonflies have wingspans of two to five inches but early fossils show them with wingspans of up to two feet.

There are more than 5,000 known species of dragonflies. They belong to the order Odonata, which means “toothed one” in Greek, referring to their serrated teeth. Some adult dragonflies live for only a few weeks while others live up to a year. Dragonflies live on every continent except Antarctica, and thrive from sea level up to the mountains, decreasing in species diversity with altitude.

Dragonflies start their life in the water. As larvae (known as nymphs) they eat pretty much anything—tadpoles, mosquitoes, fish, other insect larvae and even each other. Eventually they crawl out of the water where their larvae exoskeleton cracks open and releases first the abdomen, which had been packed in like a telescope, then its four wings, which dry and harden over the next several hours to days.

Dragonflies are expert fliers. They can fly straight up and down, hover like a helicopter and even mate mid-air. They only eat prey they catch while flying, grabbing it with their feet. Dragonflies are a great control on the mosquito population, eating 30 to hundreds of mosquitoes per day.

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Dragonflies have amazing eyes. Most of their head is devoted to their eyes [me: and Pug-like nose and mouth], giving them incredible vision that encompasses almost every angle except directly behind them. Each of their compound eyes have nearly 24,000 ommatidia (the optical units that make up a compound eye).

Dragonflies rarely use their legs for walking. They’re for catching and holding prey, perching, and climbing on plants. Each leg has two short basal joints, two long joints, and a three-jointed foot, armed with a pair of claws. The long leg joints bear rows of spines, and in males, one row of spines on each front leg is modified to form an “eyebrush” for cleaning the surface of their compound eye. [Me: why don’t the females have this eyebrush? Don’t they also need to clean their eyes?]

Many dragonflies, particularly males, are territorial. Defending a breeding territory is common, especially among species that congregate around ponds. Females mate with the holder of a territory before laying their eggs. Some dragonflies signal territorial dominance with striking colors on the face, abdomen, legs, or wings, while others engage in aerial dogfights or high-speed chases.

Dragonflies in Culture

Dragonflies are represented in human culture on artifacts such as pottery, rock paintings, and statues. They appear in Art Nouveau jewelry and as a decorative motif on fabrics and home furnishings.

Dragonflies are symbols of courage, strength, and happiness in Japan, but seen as sinister in European folklore. Some English vernacular names, such as “horse-stinger,” “devil’s darning needle,” and “ear cutter,” link them with evil or injury. In Swedish folklore it was believed the devil used dragonflies to weigh people’s souls. The Norwegian name for dragonflies is Øyenstikker (“eye-poker”), and in Portugal, they are sometimes called tira-olhos (“eyes-snatcher”).

For some Native American tribes, dragonflies represent swiftness and activity. For the Navajo, they symbolize pure water. They are a common motif in Zuni pottery. Stylized as a double-barred cross, they appear in Hopi rock art and on Pueblo necklaces.

The poet Lord Tennyson, in his 1842 poem The Two Voices described a dragonfly splitting its old skin and emerging shining metallic blue as “sapphire mail”: An inner impulse rent the veil / Of his old husk: from head to tail / Came out clear plates of sapphire mail.

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Dragonflies are often confused with damselflies, which are similar but smaller. A distinguishing feature: damselfly wings fold against their bodies when not flying, while dragonfly wings always remain outright.

Mating

And finally, all the details you wanted – or didn’t – about dragonfly mating, from Wikipedia:

Dragonflies have a uniquely complex mode of reproduction involving indirect insemination, delayed fertilization, and sperm competition. Mating in dragonflies is a complex, precisely choreographed process. First, the male has to attract a female to his territory, continually driving off rival males. When he is ready to mate, he transfers a packet of sperm from his primary genital opening on segment 9, near the end of his abdomen, to his secondary genitalia on segments 2–3, near the base of his abdomen. The male then grasps the female by the head with the claspers at the end of his abdomen; the structure of the claspers varies between species, and may help to prevent interspecific mating. The pair flies in tandem with the male in front, typically perching on a twig or plant stem. The female then curls her abdomen downwards and forwards under her body to pick up the sperm from the male’s secondary genitalia, while the male uses his “tail” claspers to grip the female behind the head: this distinctive posture is called the “heart” or “wheel.”

Egg-laying (ovipositing) involves not only the female darting over floating or waterside vegetation to deposit eggs on a suitable substrate, but also the male hovering above her or continuing to clasp her and flying in tandem. The male attempts to prevent rivals from removing his sperm and inserting their own, something made possible by delayed fertilisation and driven by sexual selection. If successful, a rival male uses his penis to compress or scrape out the sperm inserted previously; this activity takes up much of the time that a copulating pair remains in the heart posture. Flying in tandem has the advantage that less effort is needed by the female for flight and more can be expended on egg-laying, and when the female submerges to deposit eggs, the male may help to pull her out of the water.

So…complicated!

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Feature image: mating pair of green darner (anax junius), by Henryhartley, CC BY 3.0.