Damselflies are slender, colorful insects often seen flitting near ponds, rivers, and marshes. They are frequently mistaken for their larger relatives, dragonflies, but can be distinguished by their more delicate build and the way most species fold their wings back along their bodies when at rest. The reproductive behaviors of damselflies are particularly notable, involving a series of visually striking rituals shaped by intense competition to ensure genetic legacy.
Courtship and Territorial Displays
The reproductive process for damselflies begins with males establishing and defending territories around freshwater bodies that are optimal for laying eggs. A male must continually drive off rivals in aerial skirmishes to maintain control of his chosen spot. The quality of his territory is the first thing a visiting female will assess when considering a potential mate.
Once a territory is secured, the male must attract a female through courtship displays. These performances are species-specific and involve showing off characteristics like brightly colored bodies or wings. For example, the male river jewelwing (Calopteryx aequabilis) will flutter his forewings while keeping his hindwings still, revealing white spots that signal his quality. If the female is receptive to his display and accepts his territory, she allows him to initiate physical contact.
The Mating Wheel Formation
After a successful courtship, the male grasps the female by her prothorax (the section behind the head) using specialized claspers at the end of his abdomen. This connection is known as the “tandem link,” and the pair will fly together in this formation. Before transferring sperm, the male moves a packet from his primary genital opening near the tip of his abdomen to his secondary genitalia located near its base.
With the tandem link secure, the female curls her abdomen forward to connect with the male’s secondary genitalia, forming a distinctive heart or wheel shape. This “wheel position” can last from a few minutes to over half an hour. During this time, the male uses specialized structures on his penis to physically remove or compact the sperm from any of the female’s previous mates. This sperm competition ensures that his own sperm will have a higher chance of fertilizing her eggs.
Tandem Flight and Egg Laying
Following the transfer of sperm, the pair often remains in the tandem link as they fly to find a suitable location for the female to lay her eggs, a process called oviposition. The male’s continued presence is a form of guarding behavior. By remaining attached, he physically prevents other males from mating with the female and displacing his sperm before fertilization can occur.
The female uses a sharp, blade-like organ called an ovipositor to insert her eggs into the stems or leaves of aquatic plants, at or below the water’s surface. In some species, females may fully submerge to find the perfect spot, breathing from a thin film of air trapped by their wings. The male may stay connected during this process or detach and hover closely, continuing to ward off rivals until the female has finished laying her eggs.