The sight of a dragonfly on the wing is one of the more remarkable that nature has to offer. Here, with the help of some astounding macrophotography, we take a look at the life cycle of the dragonfly as well as its remarkable and unusual physiology.
The gorgeous colors of a dragonfly – these majestic insects of the air, have been a source of inspiration – and fear – to people for thousands of years. The order to which they belong is called Odonata. Many people regularly go ‘oding’ just as others go birding or butterfly collecting. Their life is cycle as unusual as their looks are striking.
A pair of dragonflies initiate the circle of life with a liaison of gymnastic prowess, while a third comes in to interrupt. With their multi-faceted eyes, a double pair of wings and an athletic and graceful looking elongated body it is no wonder that dragonflies are held in awe by a number of cultures. They are valued by farmers all over the world, as well as those inspired by the beauty of nature, as they help control the numbers of insects that can be harmful to crops.
Their eyes are made up of several thousand individual units known as photoreceptors. What they see combines the input from their eye units known as ommatidia. These are located on the convex surface of the eye and each points in a slightly different direction to its neighbor. In this way, these compound eyes have an extremely large view angle. This means that the dragonfly is able to detect the movement of its prey incredibly quickly. If humans wanted the same eyesight then we would have to grow compound eyes that were as large as our heads.
The wings may look fragile to the human eye but they are incredibly strong. They are incredibly fast, versatile and can maneuver in ways that we can only imagine. The control that they have is such that they can seem to change direction in an instant.
Water is a vital part of the dragonfly life cycle. The females must lay their eggs (called ovipositing) in or near water as their offspring are aquatic. Some species submerge themselves altogether. The naiad – or nymph – is an unappealing looking fellow (see below) who voraciously devours and small invertebrates with its extendable jaws. A nymph accidentally introduced to a household tank containing tadpoles for a nature project can within a few weeks become mysteriously empty!
The nymph form – as with every species of dragonfly – breathes in the water using gills – unusually positioned in their rectum! They can even increase their underwater speed by shooting water through their anus and giving themselves massive propulsion as a result. There is really an ugly duckling element to the life cycle of the dragonfly. It is a source of wonder that something so beautiful can emerge from such an unpromising start – at least aesthetically. Looking as if it would be at home trying to control the universe and usurp humanity in an episode of Stargate, it has to be admitted that while mature dragonflies have never bitten humans, their younger form, the nymph, has been known to give people a nasty nip!
The final molt looks as if it must be painless but it in fact it is like shimmying out of a dress when you are wet. Although they may have been in their larval stage for five years, when it is time for the adult to emerge it all happens very quickly. The larva leaves the water and positions itself to a reed or other plant. The very moment it touches the air the larvae begins to breath.
Just behind the head there is a weak spot and the adult takes advantage of this weakness by crawling out from there. It then rest, pumps up its wings and takes to the air to assume its adult life. Although it may be up to five years old in total, its life from now on is short. Some of the larger dragonfly species can live up to four months as an adult but this does seem like a short time when taking in to account the length of time they spent as nymph or naiad.
What is left when the adult dragonfly has emerged and flown away is a somewhat eerie reminder of its time spent as a nymph. Some mistake these empty shells as dead creatures slowly desiccating in the sunshine. Rather, they are a reminder that life goes on – and is often transformational!
It must be noted that not all have agreed with the innate beauty of the dragonfly form. Some cultures persist in seeing them as somewhat sinister. The English, before they learned to love the insect, called it the ‘ear cutter’ and the ‘devil’s darning needle’, seeing them as a presage of evil.
In Romanian folklore, the dragonfly was once a horse. Possessed by the devil it became small, winged an evil. This legend holds true in Malta, too, where it is literally known as ‘Hell’s mare.’ The reason for this, rather than any proof of the supernatural, is that some species can be rather large – one can quite easily imagine them as the horses of the air! The evil element probably comes from the same reasoning – some are so large that the suspicious European mind would necessarily see them as up to no good!
Swedish folklore has the dragonfly as an instrument that the devil uses to weigh the evil of people’s souls. They are also reputed to be used by trolls to makes their clothes, hence the literal translation from Swedish of their name – ‘troll’s spindle’. The Norwegians refer to them as ‘eye pokers’ and in Portugal ‘eye catcher’. In my own native Wales they are associated with the poisonous adder snake and called ‘gwas-y-neidr’ which is the ‘adder’s servant’. The snake connection continues in the southern United States where they are often called a ‘snake doctor’ as it is sometimes believed that they stitch and heal injured snakes.
The reputation of the dragonfly does seem, historically, to have fared better in the Far East. In Japan they are seen as symbols of positive human traits such as strength, courage and happiness. They make numerous appearances in literature, in particular the haiku tradition. Japan was even – in ancient myth – known as the ‘Land of the Dragonflies’. Their image also appears on the ceremonial regalia of the Emperor.
It would be unusual for at least one culture not to have found that irresistible human urge – eating – to be applicable to the dragonfly. Sure enough in Indonesia they are eaten both in their larval and adult forms. They are caught on sticky poles then fried and eaten. This is considered a great delicacy – and it has to be said that they are an excellent source of protein!