Egg

An odonate’s life starts in the egg stage. Eggs are stuck into plants (the so-called endofytic ovipositing), water or mud (exofytic ovipositing). All zygoptera are endofytic. Anisoptera are exofytic, except for the Aeshnidae, which are endofytic.
In Europe, there’s only one species that doesn’t oviposite in a very wet place: Lestes viridis puts it’s eggs in the bark of trees or bushes near water.

From the egg, a small prolarva emerges. A prolarva doesn’t look much like an odonate larva yet. Prolarval instar usually takes only seconds, then it changes into a small larva or nymph.
Odonates are hemimetabolical insects. That means that, unlike butterflies, they don’t make a cocoon and undergo a complete metamorphosis, but undergo a series of small metamorphosises until they finally change into an imago (that’s what is usually called dragonfly or damselfly, the flying creature).

As the larval skin is quite hard, the larvae cannot grow normally. Growth only occurs right after each of the small metamorphosises, during which the larva moults.
Nymphs or larvae of the European specie undergo between 9 and 16 instars before they go out of the water to moult for the last time (ecdysis). Larval development can take some months for fast growing species like Sympetrum fonscolombii to up to five years for Cordulegaster boltonii. Larval growth speed depends on the water temperature and on the amount of preys in the water: cold water species grow slower, as do the species that live in water that contains little food.
Odonate larvae live on the bottom of the water or between aquatic plants. Some species hide in the mud or between stones, with only their eyes and mandibles visible. Gomphid larvae are very hard to spot as they have almost perfect camouflage.

Larvae eat almost anything that moves and has the right size. Small larvae feed on tubifex, water-flees and other small organisms, larger larvae catch insects and even small fishes.
Zygoptera larvae mainly use their legs to swim and walk, but they also have three lamellas on the tip of their abdomen. These are also used to swim with. Anisoptera larvae don’t have such lamellas, but they can use their guts as a hydro jet.

Ischnura elegans, larva or nymph

Imago

Once fully grown, a nymph climbs out of the water, usually in the early morning. Changing into an imago is called emergence. Emerging odonates are very week and helpless. Therefore they need good weather. Larvae can wait for good weather when fully grown. Thus they can decide themselves when to emerge, within a certain range of time of course. They cannot wait endlessly for better weather, so if weather has been bad (=rainy, stormy or cold) for quite a long time, many odonates are forced to emerge while weather is still dangerously bad. Many of them die.
After having left the water, the nymph waits until it’s dry. After a few hours, it’s skin bursts at the back. Through this hole, the larva emerges. First the head appears, then the thorax and legs. The animal rests a while, then it also frees it’s abdomen. The larval case stays behind on the plant or stone and is called exuviae (plural: exuviae). These exuviae can be easily collected. Determination can be difficult but is possible. Exuviae are a certain proof that a species has been reproducing on that place! Handle with care, the empty skins are VERY fragile.
Now the wings are deployed. The veins are filled with blood fluid. The wings unfold, stretch and dry. The abdomen too stretches, it becomes longer and thinner. Then the skin hardens. After a few hours, the newly born imago (called a juvenile) is able to fly.
The first time I raised a dragonfly larva, I photographed the whole process of emerging. The photos of this process are found here.

Juveniles often leave water soon after their emergence. Far from the water, they aren’t disturbed by sexually active males. They spend their time eating small insects waiting until they are adults, which are sexually active themselves. During this period, their colours (which are very pale after emergence) become brighter. When adult, odonates return to the water to find a partner.

Adult males occupy territories near the water. These territories are defended against other males. When a female of the same species enters the territory, the male grabs her with his appendages: behind or between the eyes (Anisoptera) or at the prothorax (Zygoptera). Two odonates being attached to each other this way are called a tandem. The male transfers his sperm from the opening underneath segment 9 to the copulation device underneath segment 2 by making a loop of his (very flexible) abdomen. Then the female reaches to this copulation device with her genitalia, located underneath her segments 8 and 9. Now the odonates form a loop, called copula or mating wheel. During the copulation, males of some species remove the sperm of earlier copulations (=other males) from the female’s genitalia.
After the copulation, the females start ovipositing. All Zygoptera, most Sympetrum species and Anax parthenope remain in tandem during ovipositing. The other Anisoptera divide after copulation. With many of these species, males guard the females during ovipositing, hovering above them or sitting near them on a plant or stone.

Many Zygoptera (which are endofytic) stick their eggs in the stalks of aquatic plants. Tandems of these species descend on the plant. Then the female walks down backwards, often completely disappearing under the water’s surface. The males, still attached to the females, can pull them out again if they cannot do that themselves, so the males are some kind of lifelines. The abdomen of the female zygoptera are covered with small hairs, between which air is trapped. This air helps them to return to the water surface. Avoid touching the abdomen, for the hairs might break and then the damselflies might never get out of the water again and drown!

Exofytic species just dip the tip of their abdomen in the water to drop the eggs. Cordulegaster boltonii however is an exception: this dragonfly sticks it’s eggs into the bottom of small, sandy streams with her huge ovipositor.

The imago’s stage of an odonate’s life is quite short, compared to the larval stage: about two months is the maximum, but most odonates don’t get older than about two weeks! Here too, we can find an exception: damselflies of the genus Sympecma (including two species: S. fusca and S. paedisca) survive during winter hibernating and live during about 8 months out of the water.