Life in the air begins underwater

Odonata have distinct and quite different stages in their life cycle: the more familiar one is as aerial insects, but they begin and spend most of their life as aquatic larvae.

After breeding, dragonflies and damselflies lay their eggs in water, or very close to it. The eggs usually hatch after a month or so, but some species’ eggs overwinter and hatch the following spring, especially if laid late in the season.

After hatching, the resultant Larva – commonly called a nymph – lives underwater until it’s ready to emerge as a dragonfly or damselfly. This may take a few months in some species, while others take several years to fully develop. Typically, colder climates need a longer development period.

Body description

They are insects, and have a body divided into head, thorax and abdomen, six segmented legs, and large compound eyes. They have wing buds that will form the adult insects’ wings, but these are not yet fully developed and remain unused until they leave the water following emergence. Reproductive organs are undeveloped and non-functional. They have a distinctive Labium.

The larvae of dragonflies and damselflies have some general differences:

Dragonfly larvae

Dragonfly nymphs tend to be larger, with broader and flatter bodies, often with a pointed abdomen.

Damselfly larvae

Damselfly nymphs are usually smaller and thinner and with a less tapered abdomen, echoing the differences between them in their adult life. They have 3 Caudal Lamellae acting as gills at the tip of the abdomen.


To enable them to live underwater, dragonfly and damselfly larvae must extract oxygen from the water using gills. 

Dragonfly larvae gills are internal in the rectum, and muscular contractions draw water in through the rear and force it over the gills where respiratory transfer takes place. The water is then expelled from the anus and can be used as locomotion to escape other predators – dragonfly larvae are ‘jet propelled’.

Gills in damselfly larvae are very different, they are external and form 3 fan-like structures that situated at the end of the abdomen, called Caudal Lamellae, which are also used to propel the larva during swimming.


Odonata larvae have a uniquely adapted mouthpart called the Labium or mask, used to capture prey.

The labium is long and terminated with two pincers, at rest it is folded it beneath the head and thorax. In this position, the labium may cover the front of the head giving it the appearance of a mask, hence its common name.

The nymph extends the labium very rapidly to seize its prey, taking only 15-40 milliseconds to snatch its victim with its pincers before they can react and escape. By contrast a human blink lasts on average 100-150 milliseconds. Once captured, the labium is drawn back towards the head, and the nymph will devour its prey using a set of powerful mandibles that can easily deal with the flesh of fish and tough Cuticles of insects.



Dragonfly and damselfly nymphs use their legs to crawl amongst sediments and vegetation. This is used during hunting and general movement and exploration.

In addition to crawling, dragonfly and damselfly nymphs may propel themselves through the water for general locomotion and to avoid or escape other predators, and sometimes as a means to approach prey. Dragonfly and damselfly nymphs use very different methods to achieve this.

Swimming in damselflies

Damselfly larvae swim use horizontal undulations of their abdomen and caudal lamellae, fanning them to propel themselves through the water much as a fish uses its tail to swim.

Jet propulsion in dragonflies

Dragonfly larvae do not have caudal lamellae, and instead use jet propulsion to move rapidly through the water, the only insects to do so. Muscular contractions draw water into the rectum and another muscle contraction expels the water from the anus to rapidly propel the nymph forward.

Hunting and feeding

Odonata nymphs live in the sediments at the bottom of ponds, lakes, and rivers. Most are ambush hunters; they rely on cryptic or camouflage colouring to remain undetected as their prey passes unawares. Keeping very still and using their antennae and fine sensory hairs (Setae) that cover their body to detect their victim, they capture it using their labium. Other species though are more active stalkers and use a combination of stealth and speed to overcome their victims.


As with other insects, the ‘skin’ (Cuticle) of Odonata is made of chitin, a tough and protective but inelastic horn-like substance. Unlike our skin, chitin is not made of cellular material and is unable to stretch or grow. For a dragonfly or damselfly nymph to increase in size as it develops then, it must periodically moult or shed its skin, a process called Ecdysis

Each successive moult marks the start of a new Stadium (or instar), and dependant on species, a nymph may go through this process 8-15 times during its aquatic life.

For a short time after each moult the cuticle is soft, and until the cuticle is fully hardened the larva must remain inactive and is vulnerable to other predators. Nymphs usually stay hidden out of sight in sediments or vegetation during this time.

Each successive stadium is a stage in the nymph’s eventual development into a dragonfly or damselfly. There is no final pupal stage in the same way a butterfly has for example, and Odonata are said to undergo incomplete metamorphoses.


Leaving the water

The nymph’s final moult marks the end of the aquatic larval stage and must take place outside of water, a process known as Emergence.

The nymph ceases feeding and searches for a suitable plant stem or reed which it climbs until it is clear of the water. The stem must be free of obstruction, and the nymph may seek a better candidate if there is not enough room for the next stage of emergence.

At this stage, the nymph must stop using its gills and begin breathing air for the first time, taking in air via small holes (spiracles) in the thorax and transporting it through a system of respiratory tracts, called trachea, around its body. The process is irreversible, and once it’s begun, a nymph cannot return to the water. This is a critical time for emerging insects, and many are unsuccessful; emerging dragonflies and damselflies are easy prey to waiting predators, so emergence is often a nocturnal event.

The nymph aligns itself vertically on its chosen stem and remains motionless. Over a period of an hour or more, it sheds its larval skin for the last time, and crawls out of the shell of its larval body emerging finally as a dragonfly or damselfly. Its wings, which have been developing with each successive stadium are fully exposed for the first time.

A dragonfly emerges

The nymph stage of its life is complete, and a freshly emerged dragonfly or damselfly is no longer an aquatic insect; it has wings, it breathes air and has lost its gills and the characteristic labium of dragonfly larvae. However, it’s not yet able to fly and must undergo one last step before its transformation is complete.

The body expands, and body fluid is pumped around the network of veins in the wings, inflating them. This process may take an hour or more. Any obstruction may result in the wings or abdomen being unable to fully expand, which may be fatal. The freshly emerged insect rests while its wings and body harden, attaining its colouring also.

A newly emerged dragonfly or damselfly takes its first flight and will usually move away from water, to find food and avoid other mature Odonata. They don’t show territorial behaviour and busy themselves with feeding rather than finding a mate. A freshly emerged dragonfly or damselfly is said to be Teneral; it has pristine, shiny wings and it may lack the colouring of a mature adult. During this time Odonata may often be found some distance away from water.

Once matured, which usually takes 3-7 days, adult Odonata return to water to breed, and start the cycle once again for another generation.

Finding the shed larval skins (Exuvia) after emergence is useful and definitive proof of successful breeding at a site.