Mating commences with the male grasping the female with abdominal claspers. The female will then lay eggs while still in tandem or after the male disengages in copulation. In the species where the female detaches from the male before oviposition, the male will remain nearby on guard and will chase off other males that come near. An unprotected female, after she begins ovipositioning, may be approached by another male who may grab her and fly off in tandem. Eggs of the order Odonata will drop to the bottom muds of streams or ponds and develop into an aquatic nymph stage until they emerge one year later to propigate the species.
Most species have a single generation a year, with the egg or nymph overwintering.
In some large dragonfly species the nymphal development time can last up to three years or more. The outer skin of the nymph splits along the back of the thorax and the young dragonfly emerges. Over the next few hours, various changes, such as wing spreading, take place leaving the insect very vulnerable to predation or disturbance. If all goes well, the insect will undergo its maiden flight, often a short relatively floppy flight away from the water, when both the wings and body have sufficiently hardened. The insects leave the water for a period up to a couple of weeks while they become sexually mature.