Dragonflies are highly efficient aerial hunters and masters of maneuverability, capable of hovering, flying backward, and achieving high speeds. Their presence is often seen near water sources. The common sight of two or more dragonflies flying closely is not random, but results from behaviors tied to reproduction, territorial defense, foraging, or long-distance travel.
Flight Patterns for Reproduction
The most common reason for dragonflies to fly closely is reproduction. This process begins when the male grasps the female behind the head or on the thorax using specialized claspers, initiating a posture known as tandem flight. The pair can fly for extended periods in this arrangement, with the male controlling the flight path, often moving toward a safe location near water for copulation and egg-laying.
Once settled, the female curls her abdomen forward to connect with the male’s secondary genitalia. This action forms the distinctive copulatory wheel or heart shape, during which sperm is transferred. Tandem flight often continues after sperm transfer as a form of mate guarding, ensuring the male’s sperm fertilizes the eggs. The pair then typically flies low over the water where the female deposits her eggs onto a suitable substrate.
Defending Territory
Many male dragonflies are highly territorial, defending prime stretches of shoreline or feeding areas against rivals. These areas offer the best opportunities for catching prey and intercepting females. When an intruder of the same species enters the space, the resident male initiates an aggressive aerial display.
This encounter often manifests as a high-speed chase or a series of rapid aerial maneuvers, frequently described as a “dogfight.” The goal of this behavior is intimidation and expulsion, not physical injury, as the resident male attempts to drive the rival outside his established territory. Some species, like the common whitetail, emphasize their claim by raising a white-colored abdomen high in the air while flying, signaling ownership to approaching males.
Hunting in Swarms
Dragonflies temporarily aggregate into feeding swarms when a patch of air holds a high density of prey. This behavior is not cooperative, but rather a collective exploitation of a rich, localized food source, such as a mass emergence of midges, mosquitoes, or flying ants. The size of these swarms is directly proportional to the density of the aerial plankton they are hunting.
These gatherings can sometimes involve multiple dragonfly species, all drawn to the same concentrated area of small, soft-bodied insects. The dragonfly is a remarkably efficient aerial hunter, scooping up prey mid-flight. They consume their catch while flying, which allows them to stay within the feeding swarm and continuously exploit the temporary abundance of food.
Long-Distance Group Movements
A final reason for dragonflies flying together involves coordinated, long-distance movements known as migration. Certain species, such as the common green darner and the wandering glider, undertake extensive seasonal journeys, sometimes covering thousands of miles. These movements are often triggered by seasonal changes, such as the passage of a cold front, or resource depletion.
The common green darner exhibits a multi-generational migration pattern across North America, with individuals traveling hundreds of miles in a single flight. The wandering glider is considered the insect world’s long-distance champion, with its global migration route estimated to span over 6,000 kilometers. Traveling in large groups likely offers benefits such as increased safety from predators and the ability to better utilize favorable wind currents.