Dragonflies & Damselflies

THESE ENCHANTING INSECTS GRACE THE COUNTRY'S WATERWAYS AND MEADOWS, SHOWCASING THEIR VIBRANT COLOURS AND INTRICATE FLIGHT PATTERNS, ADDING A TOUCH OF WONDER TO THE SUMMER LANDSCAPE

These exquisite creatures are familiar to us all, especially at this time of year when a walk along any stretch of good water will be enlivened by their beauty.

Dragonfly folklore

However, they have not always been viewed with such pleasure. While the inhabitants of some countries (Japan for example) have always revered them, the British have come up with some chilling local names for them, such as Devil’s Darning Needle, Horse Stinger, Water Witch, Hobgoblin Fly, Devil's Horse, and even Snake Killer. Probably it is the generally tapering shape that put our forebears on their guard.

First and foremost, these creatures do not sting! They are totally unequipped to do so. If they are seen flying near animals like horses and cattle, it is probably because that is where the best and juiciest flies are to be found.

Also, they are incapable of sewing up your mouth, your eyes, or any other part of your body. This was a threat used by unscrupulous adults to frighten children into silence, “Stop talking, or the Devil’s Darning Needle will sew your mouth shut!” A fine way to encourage an interest in entomology!

This was a threat used by unscrupulous adults to frighten children into silence

Mike George is our regular contributor on wildlife and the countryside in France. He is a geologist and naturalist, living in the Jurassic area of the Charente

Ancient history

The Dragonflies have been on Earth for a very long time – something in excess of 300 million years, which puts them ahead of the dinosaurs in origin! The remains have been found of several undoubted dragonfly species – admittedly a bit more primitive than our modern representatives – which flew through the giant fern Coal Measure forests of the Carboniferous Period. They were of an astounding size –wingspans up to 30 inches (75 cm) which in size would have challenged a large seagull of today. How insects of that size functioned is a mystery. It has been suggested that the atmosphere must have been richer in oxygen then than it is now, to allow the creature’s lowpowered breathing-system to deliver sufficient oxygen to its muscles.

So what exactly are they?

Today these beautiful insects are a closely related group, being arranged into the order Odonata (toothed-jaw). They form two sub-orders, the Anisoptera (unequalwinged) dragonflies, whose front two wings are marginally narrower than the hind pair, and the Zygoptera (similarwinged) damselflies, whose four wings are approximately equal in breadth.

The other chief difference is that dragonflies never fold their wings but hold them always horizontally and at a right angle to the body, while nearly all damselflies fold their wings when at rest, parallel to the body.

Dragonflies have two main body shapes: needle-shaped (the “hawkers”) and flatbodied (the “darters”). They are strong fliers and can travel considerable distances. Damselflies are long-bodied and are smaller and more delicate than dragonflies. They are weaker fliers and are usually found on or near the water they developed in.

Dragonflies have huge eyes that actually touch on top of the head and bulge out sufficiently to give a good all-round viewthey can even see what’s happening behind! The number of separate lenses in a dragonfly’s eye is astounding – up to 30,000. The facets of these compound eyes are very fine, and experiments have shown that their vision is outstanding. They are easily capable of catching other, smaller insects in full flight, and their rearward vision makes them very difficult to take by surprise.

Damselflies have smaller eyes, which do not meet on top of the head but protrude slightly to allow for some rear vision.

Getting it together, Dragonfly style Mating takes place throughout summer. It is quite unlike any other mating! In order that the transfer of semen may occur, first the male must transfer his fluid from the true exit of his male system at the end of his abdomen to a secondary “delivery organ” - a bit like a water-pistol - situated near the top of his abdomen where the female’s organ can reach it. To couple successfully, the two insects must meet in a certain way. The male grasps the female just behind her head (his ability to do this is very species-specific, to ensure his claspers will engage with the grooves with which she is equipped), and she brings her abdomen up to reach his delivery organ just behind his thorax. This causes both insects to assume a hoop or looped configuration (which the incurable romantics call “The heart arrangement”). The mating may take some time, as the male also has to ensure that any deposit from a previous mating with another male is removed; he is equipped to do this! After mating, the male dragonfly will probably leave the female to get on with her laying, but the male damselfly usually stays with his female, continuing to hold onto her behind the head with the claspers at the tip of his abdomen even while she lays her eggs. This ensures that he is the father of her offspring, and that no interloper takes his place. quite astounding

Eventually, during late July or early August, the nymph (which is now a much larger creature and, in some species at least, spectacularly ugly to the human eye) climbs up a water-plant stem for a halfmetre or so. The back of the nymph splits, and the dragonfly or damselfly does a very slow back-somersault into the world, finally grasping the plant-stem below its former incarnation. It uses this purchase to pull its abdomen free of the nymph-case.

The empty nymph-case can stay clinging hollowly to the stem for days afterwards. If you examine this case carefully, you will see dried, yellowish filaments traversing the thoracic area. These are the linings of the breathingtubes that the nymph developed to allow the dragonfly to breathe air, and which are now fulfilling their function in the emerged insect. When you think about it, this change from aquatic to aerial existence, all in one leap, is quite astounding.

Adulthood

An aquatic existence

Most of the life of the developing dragonfly or damselfly is spent in water. Hatching from the egg (usually injected into a water-plant leaf or into rotting wood near water-level) the small nymph begins a strongly predatory life, lasting up to two years for larger species and involving several moults. The nymph of a damselfly can be distinguished from that of a dragonfly because it tends to be a bit more delicate in appearance and has a small fan of gills at the end of its body.

Now the adult inflates its wings and allows them to harden. The whole process takes an hour or two, and the insect is totally vulnerable throughout. I have even seen cases where a dragonfly lost its grip while drying its wings, fell into the water and drowned.

When it feels sufficiently hardened, the dragonfly or damselfly will depart to start its adult life. Not quite fully, however; for a few days it will still be fairly soft, and be rather vulnerable, not least to other dragonflies. This stage is known as a teneral dragonfly.

The colours displayed by these teneral dragonflies and damselflies are not fully developed; they will strengthen over the next few days and can become spectacular and very variable. As old age approaches, the insects can show “pruinescence”, a powdery blueing or whitening of the body colours. After death the colours fade, and collections of dead dragonflies are usually very drab exhibits - far better to photograph them!

The adults feed on smaller insects, trapping them in the “basket” formed by the legs in flight. They have serrated jaws which enable them to deal with the hard skeleton of their prey. The dragonfly’s jaws

The insects can hover, fly backwards, change direction very quickly are incredibly strong, but they are not equipped to bite a human or even a mammal like a horse.

Although the dragonfly’s flight system developed very early, it is amazingly adaptable and robust. The insects can hover, fly backwards, change direction very quickly, and in fact have control of each of their wings separately; a very sophisticated flight mechanism. They can fly at a remarkable speed; dragonflies can reach 30 km per hour for a short while (damselflies quite a bit less) and they can fly for long periods.

Adult dragonflies can live for several weeks if they make it past all the hazards of the transition to an aerial existence. They should not be confused with “Ephemeraceae”, creatures such as Mayflies, which emerge similarly from an aqueous existence but have a very short adulthood – less than a day. However, dragonflies usually end up as a meal for a larger dragonfly or a largish bird. You can encourage dragonflies and damselflies to your garden with a wellbuilt wildlife pond. (No fish though! They will eat the developing nymphs.)