Dragonflies, the hawkers

Aeshnidae family - the Hawkers

These are the hawkers, and they are the largest and swiftest European dragonflies. There are 11 British species. The adult body length ranges from 50 - 120mm, and the wingspan is up to 150mm.

Anax imperator, the Emperor dragonfly

Anax imperator, the Emperor dragonfly

The preserved specimen above is an adult male Anax imperator, the Emperor dragonfly.

It is usually bright blue with a green thorax, and has a thick dark line down the abdomen (the colours fade in preserved specimens).

It is one of the largest British species with a wingspan of 106mm and a body length of 78mm.

The adult flies in June, July and August, and it is a hawker. It is usually found flying over ponds and canals in the south of England, where it catches its prey around reed beds.

After hatching as an adult and feeding, it returns to the waterside about a week later to mate. The female lays her eggs in floating debris and plants in weedy ponds and canals.

It spends 2 years as a larva. The nymphs can grow to over 5cm long. Before hatching into an adult the nymph moves close to the surface near leaves floating on or near the surface.

Aeshna cyanea

dragionfly emerging as adult

Above is Aeshna cyanea, the Southern hawker, emerging as an adult. Its wingspan, once the wings are fully pumped up would be 100mm, and its wing length 43 - 50mm, body length around 70mm. The adult body is dark brown with green and blue markings.

Adults fly from June to October in the U. K. This dragonfly is often seen around smaller ponds. It is mainly found in the southern part of the country, but there have been a few Scottish sightings. The larva is found in ponds, lakes and canals, and prefers shallow, weedy waters. The female lays her eggs just above the water level in rotting wood, moss or stones. On hatching from the egg the nymph moves into the water.

Anax tristis, the Black emperor, Magnificent emperor

Anax tristis, the Black emperor, Magnificent emperor

Above is an adult Anax tristis, which is found in Africa. Its body length is 120mm, and wingspan is up to 135mm.

Golden-ringed dragonfly, Cordulegaster boltonii

golden-ringed dragonfly adult

The Golden-ringed dragonfly, Cordulegaster boltonii, above, flies from the end of May to mid September, and is classed as a hawker. Adults are fairly easily identified by their black and yellow rings, and bright green eyes. The wingspan is around 101mm and the hind wing length is 41 - 46mm; body length 74mm in males and 84mm in females, with the abdomen length being 54 - 60mm in males and 60 - 64mm in females. The female has the longest body of any U. K. dragonfly. It is commoner in the west of the U. K. Its range extend across Eurasia as far as India.

The adult patrols streams in a predictable flight path, and rests in reeds, heather and on boulders. Adults can sometimes be seen quite far from water. Adults eat damselflies, other dragonflies, wasps, beetles, midges, flies, butterflies, and even bumblebees.

The female lays her eggs in mud, and has a relatively long ovipositor. She usually lays her eggs in the morning, hovering over the mud and water thrusting her ovipositor into the sediment with a stabbing movement. The eggs hatch after a few weeks. It takes 2 - 5 years before the adults emerge, which they do at night, and these adults will not be sexually mature for another ten days.

The nymphs are large, 35 - 42mm, and hairy and found in good quality clear water in acidic moorland streams with sand or mud at the bottom, also in boggy pools. The nymphs lie hidden in the detritus, with just the tip of their head and tail sticking out, waiting to ambush passing prey such as insect larvae, snails, tadpoles and tiny fish.

Aeshna grandis, the Brown Hawker

Aeshna grandis, brown hawker larva

Above 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 102mm, and body length 73mm. 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.