Adults of dragonflies carry out all their life in the air, as well as the larvae grow in the water.

Life cycle begins from the egg, laid down by females in two ways depending on the species. Some of them place the eggs on water vegetation (usually Zygoptera and Aeshnidae), while others lie them down directly in the water. The eggs hatch in two to four weeks originating the larvae, whose life cycle unfolds entirely underwater. They are skilful predators, eating animal plankton, small worms, other insects larvae and smaller dragonflies larvae. Larval life can last from some months all along through some years, depending on the species and ecological conditions. Finally, after a variable serie of development stages, the larva is ready to morph into an adult. This is a really ticklish moment: it goes out of the water holding on vegetation and begins to break the exoskeleton and push out the head, then the thorax, the wings and the abdomen. This time is called “emergence” and can last some hours. During that lapse of time, wings have not hardened yet and need to reach the final shape, so in this phase the dragonfly is particularly vulnerable. When transition is accomplished, the adult dragonfly starts to fly leaving behind the empty exoskeleton of the larval stadium (called “exuvia”). In a short time it becomes sexually active and it is ready for breeding.

Mating has no parallel in animal kingdom. Male and female genitalia are on the distal portion of the abdomen. To bring sperm to the female genitalia, the male transfers it from the abdomen tip to the secondary genitalia at the abdomen base. When the male meets a female, it clasps her just behind the head with its appendages and forces her to mate. The female then brings her abdomen distal portion to male’s secondary genitalia. At this time, the two joined dragonflies create together a typical heart-shaped mating wheel.

Fertilization is delayed and occurs when the eggs are laid down. The male can go away leaving the task to the female, or can hover nearby (chasing away rivals disturbing her) or it can even share the task remaining clasped to the female and bringing her to lie down eggs (“tandem” oviposition, typical in Sympetrum, e.g.).