Dragonflies (order Odonata) possess complex mating sequences. The duration of this process, which spans distinct stages from initial seizure to post-copulatory egg-laying, is highly variable. The time spent in the physical act of copulation can range dramatically from less than a minute to multiple hours, driven by the male’s need to secure his genetic legacy.
The Tandem Linkage and Mating Wheel
The reproductive sequence begins when the male secures the female in a position known as the tandem linkage. Using specialized claspers, the male grips the female just behind her head, on the prothorax. This connection allows the pair to fly and perch together, with the male essentially steering the female as they search for a suitable mating location. This tandem flight often lasts for several minutes, serving as a protective measure against rival males and a prelude to copulation.
The male must first prepare for the act by transferring sperm from the primary genital opening to the secondary genitalia located underneath the second and third abdominal segments. He accomplishes this by arching his abdomen forward to make contact with the secondary structure, a process called sperm translocation. This unique arrangement is necessary because the primary reproductive opening is separate from the structure used for copulation. Once the male is prepared, he invites the female to begin the transfer phase.
If the female is receptive, she curves her abdomen forward and under her body to connect her genital opening with the male’s secondary genitalia. This physical connection forms the characteristic closed loop shape, often referred to as the mating wheel or heart. This acrobatic maneuver is a prerequisite for sperm transfer and is unique to dragonflies and damselflies. The wheel formation constitutes the actual copulatory phase.
Duration and Variables Affecting Copulation Time
The time spent in the mating wheel position is highly species-specific and can vary from less than one minute to several hours. Some smaller dragonfly species, like certain Chasers, can complete the entire process in as little as fifteen seconds, especially if copulation occurs while flying. Conversely, species that settle on vegetation to mate, such as many damselflies, frequently remain linked for an hour or more; the size and taxonomy of the species are major determinants of this duration.
The most significant factor influencing the length of copulation is the intense sperm competition among males. Male dragonflies often use specialized structures on their secondary genitalia, such as barbs, hooks, or paddle-like extensions, to actively remove or displace any sperm stored by the female from previous mates. This lengthy sperm removal process is directly responsible for significantly extending the time the pair spends in the mating wheel.
Environmental variables, such as the risk of predation or population density, also play a role in modulating the duration. In high-risk areas, the pair may opt for an accelerated, brief, in-flight copulation, prioritizing safety over the complete removal of rival sperm. Although the time required for sperm transfer is usually minimal, the male’s drive to ensure paternity means the pre-transfer cleaning phase dictates the overall length of the copulatory wheel.
Post-Copulatory Guarding and Oviposition
Once sperm transfer is complete and the mating wheel disengages, the male’s reproductive effort continues with post-copulatory guarding. The purpose of this behavior is to prevent rival males from mating with the female and removing the newly deposited sperm, which is crucial for the male’s paternity assurance.
Guarding takes two primary forms depending on the species.
Contact Guarding
In contact guarding, the male remains physically linked to the female in the tandem position while she lays her eggs, effectively preventing any other male from attempting a takeover.
Non-Contact Guarding
Alternatively, in non-contact or hover guarding, the male releases the female but hovers closely above or near her, aggressively chasing away any encroaching rivals.
Following copulation, the female proceeds to oviposition, or egg-laying, often under the male’s watchful eye. Dragonfly species use two main methods for depositing eggs.
Endophytic Egg-Laying
This method involves females using a hardened ovipositor to cut into plant tissue or mud to insert eggs.
Exophytic Egg-Laying
This method involves dropping eggs onto the water surface or washing them off by dipping the abdomen. The male’s continued presence ensures the eggs are fertilized by his sperm.