Examining the enchanting world of dragonflies

WHILE sitting in my garden, reading my daily newspaper, in the morning sunshine a few days ago, suddenly I was surrounded by a small swarm of midges. Out of the blue a brown hawker dragonfly appeared from nowhere. It brought back memories of the early evenings in a friend’s garden in Kuching, when drinking a ‘sundowner’ and relaxing after a full day’s work, and being chased by mosquitoes only to be relieved by the presence of a dragonfly. In both cases the midges and mosquitoes soon disappeared down the throats of the dragonflies.

In my Somerset, English garden, this hawker dragonfly with the 5cm span of its double wings glowing like burning bronze and upon spotting the midges, hovered deliberately above them before swooping down for a quick feast. I had always associated dragonflies with those that I had seen along stream and river courses and ponds. Thinking again, I realised that a big river is but eight minutes’ walk through a field from my English house and the open road drain only two minutes’ walk from my Kuching abode.

True dragonflies as we now know them have been on Earth since Jurassic times (from 201 to 145 million years ago) and belong to the order Odonata, which is split into two suborders: Anisoptera, distinguishing them from the other suborder given to damselflies. The Bahasa Malaysia word for dragonfly is pepatung. Some readers may well remember the magnificent collection of 30 sen Malaysian stamps issued in 2000 depicting the myriads of dragonflies found in Malaysia.

Worldwide, there are over 3,000 species living on every continent except Antarctica, which are able to live up to 3,700 metres in height and within the Arctic Circle.

Complex bodily structure

These sturdily built, fast flying insects with speeds of between 54 and 97 kph, hold their wings horizontally both when flying and at rest. With a chitinous exoskeleton, their heads are large with very short antennae and hold two enormous compound eyes, which can see in 360 degrees and with much faster than humans by 2,000 images per second. Their mouths have jawed teeth and a tongue-like feature which can quickly be released to catch their prey.

Their thorax is of a robust nature to support two pairs of wings and three pairs of legs. Long-veined wings require a form of blood supply to stiffen them, and the hind wings are broader than the forewings. Dragonfly legs are used for catching and gripping their prey and for perching and scrambling along plants. Each leg has a pair of claws for ripping off the wings of the insects devoured.

The dragonfly’s abdomen is comprised of 10 segments, and it is here that its reproductive system is housed. Often dragonflies can be seen flying in tandem, which is part of their mating ritual. Before he flies in pursuit of a female, the male transfers his sperm to a special organ on the underside of his body. By grasping a female by the neck using ‘claspers’ at the tip of his body, the female then twists her body forwards below him to receive the sperm in her open ovary.

Egg laying

The female deposits the eggs, via her ovipositor, in one of two ways by either slitting open a plant leaf or stem so that she can push her eggs inside or by shaking out the eggs from her abdomen as she skims over the surface of a river or stream. A clutch of 1,500 eggs are laid each time and these eggs take about a week to hatch into aquatic nymphs.

The nymphs, dependent upon their species, moult between six and 15 times as they grow bigger and breathe through their gills, propelling themselves at high speeds through the water. This nymph stage can last for up to five years in larger species of dragonfly but in the smaller species between two months and three years. The nymphs feed on tadpoles, very small fish, and mosquito larvae.

When ready to metamorphose into the adult stage, the nymph breaks the surface of the water at night and remains stationary thus allowing its breathing system to adapt to air. It then climbs onto a reed and finally moults, emerging from its nymph’s exoskeleton before plumping out its body and pumping haemolymph (a blood like substance) into its wings while basking in the sun and thus allowing heat to activate its wing veins before taking to the air, hovering for a few moments, flying backwards and eventually flying off in a forward direction.

The metamorphosis from nymph to fully fledged dragonfly was encapsulated in 1833 by the very observant English poet Alfred, Lord Tennyson in his poem, ‘The Dragonfly’:

“Today I saw a dragonfly,
Come from wells where he did lie.
An inner impulse rent the veil
Of his old husk, from head to tail
Came out clear plates of sapphire mail.
He dried his wings; like gauze they grew
Thro’ crofts and pastures wet with dew
A living flash of light he flew.”

Diet

They feed on practically any small insect that flies such as midges, mosquitoes, smaller dragonflies, moths, and butterflies, catching up to 95 per cent of the prey they chase.

Their own predators are kestrels, merlin, hawks, swifts, swallows, flycatchers, and even certain species of wasp. In their nymph stage of life, dragonflies face dangers from water mites and other waterborne parasites, ducks, herons, newts, frogs, and water spiders.

Yet, the greatest threats are human induced in forest clearance as well as the drying up of streams and pools. Drainage of low-lying land can lead to a reduction in dragonfly numbers but where rice is grown, these fliers act as natural pest controllers attacking the rice borne insects and thus leading to increases in crop yields.

I know that summer has arrived when I see dragonflies in my garden. The fascinating colours of their wings in the sunshine seem to sparkle like champagne and the metallic colours of the segments of their abdomen brighten up even overcast skies.

In literature their fortunes are varied in the ways they are portrayed depending on which part of the world they are described. In Europe, dragonflies are portrayed as sinister creatures with such terms as ‘the devil’s darning needles’ and ‘horse stingers. In Wales, they are known as ‘the snake servants’. In Japan, they are portrayed in folk paintings and in Haku poetry.

In my childhood, in the 1950s I frequently saw Dragonfly helicopters overhead. First flown in 1953 by the Royal Navy Fleet Air Arm near my Cornish boyhood home, they were often on air-sea rescue missions. Built by Westland helicopters, they could only carry three people besides the pilot. Today, versions of the Dragonfly helicopter are now housed in the RNAS Museum in Yeovil, Somerset and only about 40 minutes’ drive from where I live.

The numerous species of Malaysian dragonflies need further detailed research as to their locations, behaviour, and breeding details. Perhaps, this may be seen as a topic for conservation groups and even PhD students.