During the Carboniferous there were huge dragonflies (with wingspans as large as that of a seagull today) to be found in what is now England. At that time insects were the only flying animals. It is believed that the huge dragonflies were slower fliers that those of today. Most damselflies complete their lifecycle in one year. True dragonfly nymphs can take up to 5 years before reaching adulthood. There are usually 10 - 15 moults as nymphs.

The nymphs (see Aeshna grandis left and the damselfly nymph below left) are aquatic, carnivorous and sluggish. Damselfly nymphs are slender, with 3 leaf-shaped tails, and are much better swimmers than the fatter dragonfly nymphs. On hatching from the eggs the larvae start feeding at once. They have a prehensile lower lip (called the mask) which is folded under the head at rest. This has moveable teeth, and the whole thing can shoot out at great speed to grab prey. On the left the mask is partially extended. Dragonfly nymphs can swim very fast for a short distance by jet propulsion. They can forcibly eject water from the gill cavity in their abdomen and this provides forward thrust for a short distance - usually enough to grab prey. Damselfly nymphs cannot do this. The larvae breathe underwater through tracheal gills. They tend to creep around the bottom of ponds and streams searching for prey. When a nymph is about to moult into an adult it crawls out of the water. Dawn or dusk during fine weather are the most common times for moulting. It can take nymphs from 1 to 5 years to mature depending on species.

Left is the nymph of Aeshna grandis, the brown hawker. The adult flies from July - October in England and Ireland. It is fairly easily recognised as it has amber-tinted wings and a brown body. The adult wingspan is around 102 mm, and body length 73 mm. Adults tend to hawk around pond edges and down the middle of streams. The males are fiercely territorial and will attack other males. The females deposit their eggs in plants or floating wood.

Below left is a damselfly nymph, possible Lestes sp. Note the leaf-like tail filaments and slimmer body. This one came as an egg in the stem of some plants I ordered for my pond. With the popularity of garden ponds increasing this may be a new method of dispersal. Adult Lestes sp. fly from June until the first frosts.

The adults are strong fliers and eat other insects, especially mosquitoes and other small flies, that they catch on the wing. The three pairs of legs form a basket to scoop flying prey. However because of the positioning of the front legs Odonata cannot walk or crawl. The beautiful colours of the adults fade after death.

Females and males of the same species are often different colours, and younger adults are usually a paler colour than older ones. The venation of the wings is used in identification to species level, however there is disagreement between entomologists in naming the veins, so identification for a beginner is usually easiest using illustrations.

They have 10 or 11 abdominal segments. All males have a pair of claspers on segment 10, and their reproductive organs on segment 2 or 3. In females the ovipositor is in segment 8 or 9. Some females may have a pair of appendages on segment 10.

Before mating the male must transfer sperm from the genital opening on segment 9 to the reproductive organs on segments and 3. Then on finding a female he grabs her by the neck with his claspers. She curves her body around until the tip of her abdomen touches his reproductive organs in segment 2 and 3 to collect the sperm. This is known as the copulation wheel. After mating the pair may fly in tandem with the male leading.

The female dragonfly places her eggs in the water, usually on the stems of aquatic plants. Some species actually crawl underwater to place their eggs deeper, some have a saw-like structure on the ovipositor to make slits in plants enabling them to place the egg inside the stem, and others, such as Libellula depressa, below, just skim over the water dipping the tip of their abdomen in and scattering the eggs singly. In some species the male holds on to the female while she lays eggs. Adult life span can be as long as 2 months, but is usually no more than 2 or 3 weeks.

Libellula depressa, right, is also known as the broad-bodied chaser and broad-bodies Libelulla. It belongs to the Libellulidae family which has 1300 species worldwide, and 14 native British species. Libellulids are shorter than most other Ansioptera, and a flattening of the abdomen makes them appear stout. They are commonly known as darters or skimmers as unlike other Ansioptera they do not patrol a territory, but tend to perch in the same spot and dart out to capture any passing prey. In the UK the adults fly from May until September.

Libellula depressa males have a blue abdomen except for brown spots at the side. The females have yellow spots down the side of a brown abdomen. Both have dark brown patches at the base of the wings. The wingspan is around 74 mm and body length around 44 mm. The males are territorial and use the same parch for days on end. Females tend to rest on vegetation near to ponds. They are fairly common in southern England and Wales. Adults fly from late May - September.

It flies from dawn to dusk, and prefers habitats that are open.
The nymphs are 40 - 46 mm long when fully grown. They are tolerant of semi-polluted waters, so can breed in canals, and are also found in large ponds and the weedy margins of lakes.
The adult female lays her eggs in floating timber or vegetation close to the water's edge.