Dragonfly mating produces one of the most recognizable sights in the insect world: two dragonflies locked together in a loop sometimes called a “mating wheel” or “heart.” The posture looks acrobatic, and it is. It exists because dragonflies have an anatomical arrangement found in no other insect group, with the male’s reproductive organs split between two body segments. That quirk sets off a chain of behaviors involving sperm competition, female counter-tactics, aerial combat, and even death-faking that make dragonfly reproduction far more complex than a brief mid-air coupling.
How the Mating Wheel Forms
Male dragonflies produce sperm near the tip of their abdomen, in segment nine. But the organ they use to deliver that sperm sits far forward, underneath segments two and three. Before mating, a male curls his abdomen forward and transfers sperm from the tip to this secondary set of genitalia, essentially loading himself. No other insect order uses this two-step system.
When a male spots a receptive female, he grabs her by the head (in true dragonflies) or the front of the thorax (in damselflies) using clasping appendages at the end of his abdomen. This is the “tandem” position. To complete the connection, the female then swings the tip of her own abdomen forward and up to meet the male’s secondary genitalia. The result is the wheel shape, with both insects curving into a rough circle. They can fly, perch, or hover while coupled, and copulation can last anywhere from a few seconds to several hours depending on the species.
Why Males Remove a Rival’s Sperm
The secondary genitalia are not just delivery tools. In many species, the male’s penis is equipped with structures that scoop out or displace sperm left behind by a previous mate. This was first demonstrated in a damselfly species, where scanning electron microscopy revealed backward-pointing hairs and a flexible, extendable head on the penis that physically catches and removes rival sperm from the female’s storage organs. The penis of that species serves a dual purpose: sperm removal first, then sperm transfer.1Science. Dual Function of the Damselfly Penis: Sperm Removal and Transfer
The practical effect is dramatic. In some species, a mating male can displace the vast majority of sperm stored from an earlier copulation before depositing his own. This means the last male to mate before egg-laying has a large paternity advantage, which in turn explains why males invest so much energy in guarding females after copulation and why they sometimes remain physically attached to her during egg-laying. Every minute a female spends unguarded is a minute another male could mate with her and undo the previous male’s reproductive investment.
Female Choice Does Not End at Copulation
For a long time, the dragonfly mating story was told almost entirely from the male perspective: males compete, males guard, males remove sperm. But females are not passive participants. In at least three odonate species, researchers have documented that females selectively eject sperm after mating, and the volume they eject correlates with which male they mated with. In a tropical damselfly with two distinct male forms, territorial and non-territorial, females consistently ejected more sperm after mating with non-territorial males than with territorial ones.2ResearchGate. Female Choice in Damselflies and Dragonflies
This is a form of cryptic female choice, meaning it happens after mating and is invisible to the casual observer. The female appears to have mated normally, but she adjusts how much of the male’s sperm she retains based on some quality signal, possibly territory ownership as a proxy for overall fitness. It adds a hidden layer to the reproductive contest: even a male who successfully mates and guards a female is not guaranteed paternity if she decides to dump his sperm.
Signals That Precede Mating
Before any of the physical mechanics begin, dragonflies and damselflies rely on signals to find, identify, and evaluate potential mates. The most obvious of these is color. Odonates are among the most vividly colored insects on Earth, and their coloration serves multiple functions including species recognition, mate assessment, and predator avoidance.3Journal of Zoology. Dragon colors: the nature and function of Odonata (dragonfly and damselfly) coloration Males of many species develop brighter or more distinctive color patterns as they mature, and females of some species exist in multiple color forms, which can complicate mate recognition for males.
Chemical signals play a role too, though this area of odonate biology is much less studied than visual signaling. Research on a polymorphic damselfly species found evidence that males can distinguish females from other males by scent, likely using cuticular hydrocarbons, the waxy compounds that coat the insect’s exoskeleton. No sexual pheromone has been formally documented in any dragonfly or damselfly, but the cuticular hydrocarbon profiles differ between the sexes and could serve as recognition cues.4PLoS ONE. Scent of a Dragonfly: Sex Recognition in a Polymorphic Coenagrionid This is a frontier in odonate research. Most work on dragonfly mating has focused on what you can see, and the chemical dimension is only beginning to be explored.
Mate Guarding and the Tandem Link
After copulation, males face a dilemma. The same sperm-displacement abilities they used to supplant a rival’s sperm could be used against them by the next male. The solution, in many species, is to stay attached. Males of numerous dragonfly and damselfly species maintain the tandem position with the female while she lays her eggs, physically preventing other males from coupling with her. In some species the male releases the female but hovers nearby, chasing off intruders.
How long a male guards and whether he stays in contact or hovers at a distance varies across species and even within a species depending on local conditions. When rival males are abundant, guarding tends to be more intense and prolonged. When competition is lower, males sometimes release females sooner and go looking for additional mates. The trade-off is straightforward: every minute spent guarding one female is a minute not spent mating with another, but releasing too early risks losing paternity entirely.
Playing Dead to Escape Harassment
Not every encounter between a male and female dragonfly is welcome. Males of many species will chase and attempt to grab any female they encounter, regardless of whether she has already mated, is busy laying eggs, or simply is not interested. Females have limited options for escape since males are typically faster fliers. In at least one European species, researchers observed a remarkable counter-tactic: females crash to the ground when chased and lie completely still.
In a study of this behavior, about 87% of females that crashed to the ground after being chased by a male remained motionless, and roughly three-quarters of those females successfully fooled the pursuing male, who lost interest and flew away. The females were not injured or unconscious. When a researcher tried to catch them by hand during the act, they sprang up and escaped almost every time.5Ecology. Faking death to avoid male coercion: Extreme sexual conflict resolution in a dragonfly The behavior exploits the fact that male dragonflies primarily detect females by movement; a motionless dragonfly on the ground is essentially invisible to them.
Whether to call this “death feigning” has generated some debate among researchers. A critique of the term argues that the behavior does not match the formal definition of thanatosis (death feigning as an anti-predator defense) and instead proposes calling it “drop and stop” behavior, a more neutral description of what the female actually does.6Odonatologica. Death feigning in sexual conflict between dragonflies (Odonata): does it exist? The semantic argument aside, the behavior itself is well documented and represents one of the more extreme examples of sexual conflict resolution in insects.
How Eggs Are Laid
Egg-laying in odonates falls into two broad categories. Dragonflies in the suborder Anisoptera typically drop or flick their eggs into the water, either while flying in tandem with a male or solo after being released. Damselflies and some dragonfly families use a very different approach: they have a bladed ovipositor that saws into plant tissue, inserting eggs one at a time into stems and leaves submerged in or overhanging water.
The endophytic (inside-plant) ovipositor is a sophisticated structure. Research has shown a positive correlation between the mechanical hardness of the ovipositor and the stiffness of the plant substrates the species prefers, suggesting the tool is finely tuned to the species’ egg-laying habitat.7PubMed. Mechanical properties of the endophytic ovipositor in damselflies (Zygoptera, Odonata) and their oviposition substrates The cutting blades of the ovipositor are also equipped with arrays of sensory receptors, mechanoreceptors that allow the female to feel the stiffness and resistance of the plant as she pushes into it.8PubMed. The mechanoreceptors on the endophytic ovipositor of the dragonfly Aeshna cyanea (Odonata, Aeshnidae) Think of it as tactile feedback: the female can sense whether a plant stem is suitable before committing her egg to it.
This matters because egg placement affects survival. Eggs inserted into living plant tissue gain some protection from desiccation and predation, but only if the plant is structurally sound. A female inserting eggs into a stem that is too soft might find them exposed; a stem that is too hard might break the ovipositor. The sensory array lets her make that judgment in real time.
The Dangers of Egg-Laying
The moments during and after egg-laying are among the most perilous in a dragonfly’s life, especially for females. A study of the dragonfly Sympetrum danae found that about 14% of females that began laying eggs while in tandem with a male were killed by frogs, and 10% of solitary egg-laying females suffered the same fate. Males in tandem fared much better: only about 3% were taken.9Animal Behaviour. Costs and benefits associated with oviposition site selection in the dragonfly Sympetrum danae (Odonata: Libellulidae)
The disparity makes sense when you consider the mechanics. The female is the one who must approach the water surface or submerge to deposit eggs, putting her within striking range of aquatic predators. The male, when present, rides above. This asymmetry in predation risk adds another dimension to the mate-guarding question. From the female’s perspective, having a male in tandem during oviposition may offer a modest benefit: the male’s presence and vigilance can deter some threats, even if his primary motivation is paternity assurance rather than her safety.
Flight Mechanics During Mating
Dragonflies are among the most agile fliers in the animal kingdom, and part of their aerial skill comes from having two pairs of wings that can beat independently. During normal hovering, dragonflies often beat their fore and hind wings almost perfectly out of phase, with the hind wings leading the fore wings by close to 180 degrees. This out-of-phase pattern is energy-efficient, producing enough lift to support the body at low power cost.
But when a dragonfly needs more lift than its own body weight, for instance when flying in tandem with a mate, carrying prey, or hovering while drenched in dew, it shifts to a nearly in-phase wing beat, with the fore and hind wings moving closer together in timing. Research using computational modeling of dragonfly-inspired tandem wings found that a phase difference around 22.5 degrees produced maximum lift, more than 20% above body weight, with high efficiency.10Royal Society Open Science. Tandem-wing interactions on aerodynamic performance inspired by dragonfly hovering At 180 degrees out of phase, lift matched body weight with minimal energy expenditure. The dragonfly essentially has two gears: a cruising mode and a heavy-lift mode, selectable by adjusting wing timing. Tandem mating flights, where the male must support both his own weight and the drag of an attached female, likely demand the high-lift wing-beat pattern.
Getting the Body Ready to Compete
A dragonfly does not emerge from its aquatic larval stage ready to mate. There is a maturation period, lasting days to weeks depending on the species, during which the adult body undergoes significant physiological changes. Flight muscles are a key bottleneck. Research on the dragonfly Libellula pulchella has shown that alternative splicing of a key muscle protein gene changes as the insect ages, effectively “gearing” the flight muscles for different demands. Young adults have muscles tuned for economical, low-power flight suitable for feeding and dispersal. As they mature, the muscles shift toward maximum power output, the kind needed for the explosive territorial flights and aerial chases that determine mating success.11Integrative and Comparative Biology. From Molecules to Mating Success: Integrative Biology of Muscle Maturation in a Dragonfly
This means a male dragonfly’s mating prospects are tightly linked to the state of his flight muscles. A male who arrives at a breeding pond before his muscles are fully mature may be able to fly, but he will be outmaneuvered in aerial contests by older, fully matured males. The physiological readiness window constrains when an individual can enter the reproductive arena. For males, premature attempts at territory defense are likely to fail; for females, the timing of muscle maturation influences when they can reach and evaluate oviposition sites efficiently enough to survive the predation risks that come with egg-laying.
The Tandem Pair as an Ecological Unit
When a mating pair flies in tandem, they become something neither individual is alone: a heavier, less maneuverable, more conspicuous unit navigating a landscape of predators, competitors, and environmental hazards. The male has a paternity incentive to stay attached, but staying attached makes both insects more vulnerable. The female needs to reach water and a suitable substrate, but she is constrained in where and how she flies by the male gripping her head or thorax. The competing interests of the two individuals play out in real time during every tandem flight.
Predation data from Sympetrum danae illustrate the trade-offs. Males in tandem were taken by frogs at much lower rates than females, which suggests the male’s position in the pair is physically safer. But the male is not risk-free: he is still more conspicuous than a solitary male and is constrained in his ability to escape because he is coupled to another insect. For the female, the calculus is murkier. She faces higher predation risk than a solitary female in some contexts, but she also gains the assurance that no rival male will intercept her and force a new copulation that wastes her time and energy.
The entire mating system, from the secondary genitalia to sperm removal, from mate guarding to death-faking, from ovipositor sensors to wing-beat gearing, reflects an evolutionary arms race between males competing for paternity and females retaining control over reproduction. Each behavioral innovation by one sex generates selective pressure for a counter-move by the other. The result is one of the most elaborate mating systems in the insect world, refined over more than 300 million years of odonate evolution.