Good Natured: Dragonfly and Damselfly Mating Rituals

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It's been said, by more than one starry-eyed romantic, on more than one occasion, that love makes the world go 'round.

After much research, and thorough observation, I'm about ready to agree—but with one tiny caveat. Rather than 'round, I'd say the world actually goes round—no apostrophe needed. Because rather than a preposition, I'm talking about a shape. And the world to which I'm referring—well, it's the realm of Odonata, the dragonflies and damselflies.

These familiar insects don't need any introduction—I think we've all seen one at one time or another whizzing above a wetland or hovering overhead. (Just as a refresher—at rest, dragons hold their wings straight out, while damsels fold theirs over their backs.) They're known variously as mosquito hawks, darning needles and horse stingers, all names that refer to their elongated bodies and hunting prowess. (And, no, they don't bite humans, unless you mess with them too much. In which case you kinda deserve to get bit…)

But before I digress too far, I want to circle back and focus on today's topic, which is the fantastic acrobatics of odonates in mating flights. Also known as a wheel formation, this peculiar pose occurs when a male and female unite and prepare to combine their genetic material.

Male dragonflies are equipped with three small structures at the tip of the abdomen:  two stiff cerci or “hooks" and, between these, a smaller appendage known as an epiproct. Male damselflies have two cerci and two paraprocts. Whether three or four in number, these tiny bits work together and are known informally as claspers.

(If you've ever seen someone playing a claw machine—those ubiquitous money-grabbers in arcades, bowling alleys and select dining establishments--you might be familiar with how effective a pronged appendage can be at grasping, or clasping, objects. If you've ever seen me playing a claw machine, you might also be familiar with how ineffective a claw machine player can be, but that's another story for another time.)

What's really cool about these terminal abdominal appendages is that they are species specific. It is literally impossible for a male odonate to pair up with a female of a different species. His cerci fit precisely into two plates on the conspecific female's thorax, like a key fits into a lock. Click!

Once this contact is made, the male is in front of the female. The female responds by curling her abdomen beneath her body and reaching forward, until it touches the underside of the male.

The resultant round configuration, also known as the wheel formation, varies in duration depending on species. For some dragonflies, mating is nearly instantaneous. For some damselflies, the process may last for hours. Intervals for other dragons and damsels fall somewhere in between. Regardless of length, this time of wheeling about is when things get really interesting.

Because odonates, in fact insects in general, do not form pair bonds, multiple matings may occur. Males can be assured of passing along their genetic material only if they are the last individual with which the female has contact prior to depositing her eggs.

As a result, male dragons and damsels have developed a variety of strategies for removing any traces left by prior suitors. Males of some species possess small structures that function like scoops or brushes; others have “tampers" that push prior deposits out of the way. Still others dilute any previous sperm, effectively weakening the competition.

The guardianship doesn't end there. Some males remain attached, though not in a wheel formation, throughout oviposition, or egg laying. Other males opt to stay nearby and guard their mates until eggs are deposited.

You'd think that once the acrobatics and intrigue were over, the odonates' love story would end. Well, not quite. They have time on their side—unlike many other insects. Take, for instance, mayflies. These famously short-lived species spend much of their one-to-two year lifespan as nymphs; as adults, they don't even feed. Their mating activities, as a consequence, are one-and-done affairs.

Dragonflies and damselflies, however, feed mightily as adults, and enjoy a lengthy—in insect terms—adult phase of a few weeks to a few months, with larger species generally lasting longer than smaller ones.

What this fact means for dragons and damsels is that they, both males and females, will mate multiple times over the course of their adult lives. What it means for us is the chance to witness these enchanting rituals time and again, from now until the first heavy frost. Because the cycle just keeps going 'round and 'round.

I mean…round.

Pam Otto is outreach ambassador for the St. Charles Park District. She can be reached at potto@stcparks.org.