Odonata have two strikingly different life stages. Although we recognise them as aerial insects, dragonflies and damselflies spend most of their lives underwater, largely unseen, as larvae.
After mating, females lay their eggs in or near water. Most hatch within a month, but some species overwinter and hatch the following spring, especially those laid late in the season.
Once hatched, the larva – commonly called a nymph – lives underwater until it is ready to emerge as an adult dragonfly or damselfly. Development may take only a few months in some species, while others require several years, particularly in colder climates.
As insects, Odonata larvae have a body divided into head, thorax, and abdomen, six segmented legs, and large compound eyes. They also possess wing buds, which will form the adult wings but remain unused until emergence. Their reproductive organs are undeveloped at this stage. A distinctive feature of all larvae is the specialised labium or ‘mask’.
Dragonfly larvae
Damselfly larvae
To survive underwater, Odonata larvae must extract oxygen from the surrounding water, but dragonflies and damselflies achieve this in very different ways, reflected in their appearance and behaviour.
Odonata larvae possess a uniquely adapted mouthpart called the labium, or ‘mask’, used to capture prey.
At rest, the long labium folds beneath the head and thorax, often covering the face like a mask. When hunting, the larva extends it with astonishing speed – taking only 20–60 milliseconds to seize prey, far faster than a human blink. Once captured, prey is drawn back to the mouth and consumed using powerful mandibles capable of cutting through fish flesh and tough insect cuticles.
As ambush predators, staying still and hidden is advantageous, so larvae movements are generally local and limited, shaped by habitat structure, prey availability, and the need to avoid predators. They move short distances at a time, crawling or swimming between vegetation, silt, and hiding places.
Both dragonfly and damselfly larvae use their legs to crawl among sediments and vegetation while hunting or exploring.
Damselfly larvae swim by undulating their abdomen and fanning their caudal lamellae, moving through the water in a way that resembles a fish using its tail.
Dragonfly larvae lack caudal lamellae and instead use a unique form of movement: jet propulsion. By drawing water into the rectum and forcefully expelling it, they can surge forward with remarkable speed – making them the only insects known to use this method of locomotion.
Odonata larvae live among the sediments of ponds, lakes, and rivers. Most are ambush predators, relying on camouflage and stillness to avoid detection. Using their antennae and fine sensory hairs (setae), they detect passing prey and strike with the labium. Some species are more active hunters, combining stealth with sudden bursts of speed.
Like other insects, Odonata have a cuticle made of chitin – tough, protective, and inelastic. Because it cannot stretch, larvae must periodically shed their skin in a process called ecdysis.
Each moult marks the start of a new stadium (or instar). Depending on species, larvae may moult 8–15 times during their aquatic life. After each moult, the new cuticle is soft, leaving the larva vulnerable; it typically hides among vegetation or sediment until the cuticle hardens.
Odonata undergo incomplete metamorphosis, meaning there is no pupal stage. Each stadium brings the larva closer to its final form.
The final moult must occur out of the water, in a process called emergence. When ready, the larva stops feeding and climbs a suitable plant stem or reed. The surface must be clear of obstructions to allow the next stage to proceed safely. This is a critical time for emerging larva, and many are unsuccessful.
At this point, the larva stops using gills and begins breathing air through spiracles in the thorax. This transition is irreversible; once begun, the larva cannot return to the water. Because emerging insects are vulnerable to predators, emergence often occurs at night.
The larva positions itself vertically and remains still. Over an hour or more, it splits and sheds its final larval skin, revealing the adult dragonfly or damselfly. The wings, which have been developing internally through each stadium, are exposed for the first time.
The newly emerged insect is no longer aquatic. It now has wings, breathes air, and has shed both its gills and the larval labium. However, it is still unable to fly. To prepare for its first flight, body fluids are pumped into the wing veins to expand them fully – a process that can take an hour or more. Any obstruction during this stage can distort the wings or abdomen, potentially impairing the insect’s ability to fly or breed, and can be fatal.
Once the wings and body harden and the insect gains its initial colouring, it takes its first flight. Newly emerged individuals, known as tenerals, have shiny, pristine wings and often lack the full colours of mature adults. They typically move away from water to feed and avoid territorial adults.
After maturing over 3–7 days, adult Odonata return to water to breed, beginning the cycle anew.
Finding the shed larval skins (exuviae) is a reliable indicator of successful breeding at a site.