Dragonflies are captivating insects found across the globe, known for their striking appearance and aerial agility. Their ancestors date back over 300 million years, predating dinosaurs. Their large, multifaceted eyes, transparent wings, and slender bodies give them their distinctive form. With around 3,000 to 6,500 known species, dragonflies inhabit every continent except Antarctica.
From Egg to Nymph: The Aquatic Stages
The life cycle of a dragonfly begins with an egg, often laid in or near water, such as still ponds or streams. Female dragonflies may deposit their eggs directly onto the water’s surface, on aquatic plants, or even insert them into plant tissue or damp soil. These eggs vary in appearance, some being rice-shaped while others are ellipsoidal or the size of a pinhead. Hatching typically occurs within one to five weeks, depending on the species and environmental conditions.
Upon hatching, a tiny prolarva emerges, quickly molting into the nymph, also known as a naiad. This aquatic stage represents the longest period of a dragonfly’s life, lasting anywhere from two months to five years, with many species spending one to two years underwater. Dragonfly nymphs are voracious predators, equipped with six legs and a unique, hinged lower jaw called a labium, which extends rapidly to snatch prey.
They feed on various aquatic organisms, including small insects, mosquito larvae, worms, snails, leeches, tadpoles, and small fish. As they grow, nymphs undergo multiple molts, shedding their exoskeletons between 6 to 15 times. They breathe underwater using internal gills located in their rectum, and can propel themselves by forcefully expelling water.
The Dramatic Emergence
Once fully grown, the nymph emerges from its aquatic home. It ceases feeding and typically crawls out of the water, often at night, onto a plant stem, rock, or other sturdy surface. It anchors itself, and its respiratory system adapts to breathing air. The final molt commences, with the nymph’s skin splitting open behind its head.
The adult dragonfly extracts itself from the nymphal exoskeleton, known as the exuvia, which is often left clinging to the surface. Its new body is soft and pale. The wings, initially small and crumpled, expand and harden as fluids are pumped into their intricate veins. This entire process can take one to three hours, during which the dragonfly is vulnerable to predators and environmental factors.
The Adult Dragonfly: Life in the Air
After transformation, the adult dragonfly enters its aerial stage, known for its flight and predatory skills. Adult dragonflies have a slender body, two pairs of transparent wings, and large, compound eyes that cover nearly 360 degrees of vision. Many display iridescent or metallic colors. They are agile fliers, capable of hovering, flying backward, and reaching speeds of 35-60 miles per hour.
As adults, dragonflies are active predators, hunting other flying insects such as mosquitoes, midges, and moths. They often catch them mid-flight using their bristly legs. They typically inhabit areas near water bodies, but can also be found in meadows. Reproduction involves the male transferring sperm to secondary genitalia, then grasping the female behind her head with claspers. The female curls her abdomen forward to connect with the male’s secondary genitalia, forming a distinctive “wheel” or “heart” shape for sperm transfer.
After mating, females lay their eggs, either by dipping their abdomen into the water to release them or by inserting them into plant tissue. While the nymph stage is prolonged, the adult dragonfly’s lifespan is comparatively short, typically ranging from a few weeks to about six months, depending on the species and environmental conditions.