The common whitetail has a long flight season, from early spring to late autumn (2), although the exact length of the season varies depending on the location (4) (7). This dragonfly feeds on small insects which it captures during flight (4).
Male common whitetails are highly territorial during the breeding season. An adult male will defend its mating territory along the edge of a pond, lake or slow-moving stream (8), perching along the water’s edge and patrolling the shore to drive off other males (4).
The male performs a ritualised aggressive display (9), known as a ‘duel flight’ (10), when defending its territory (9). The territory holder and the intruding male will face each other and mutually display (11), elevating their abdomens to show the characteristic chalky white colouration (4) (9) (10) (11), and engaging in a sequence of pursuit and retreat around the territory (4) (9).
The success of the male’s territorial display is correlated with the whiteness of the abdomen, with older, more mature males generally being more successful than young, immature males (11). However, territorial defence is very energetically expensive (8), and male common whitetails are only able to maintain their territories for several hours each day (4) (8). This results in complex territorial patterns, whereby up to seven or more males may share and defend a single territory at different times throughout the day (8). Larger males typically defend larger territories (4).
The female common whitetail visits breeding sites every few days, usually around midday (4), and will frequently reject one or more mating attempts before finally copulating (8). Copulation is very brief, lasting only a few seconds, and is followed immediately by oviposition (4) (8). The female taps the water with her ovipositor (4) (7) (8), laying around 25 to 50 eggs with each tap. The female may deposit up to 1,000 eggs in total, with the eggs generally laid close to floating vegetation or clumps of mud (4). During oviposition, the female is usually guarded by the male, who will hover just above the female as the eggs are laid (4) (8). Reproductive adult common whitetails may live for up to 36 days (4).