Dragonflies and Damselflies in Essex
Some things take many years to perfect, decades or even centuries of fine tuning, of practising making perfect. Some things however, find perfection early on. Perfection, not just at the time of making, but also over the countless millennia ahead of it. And so it is with the dragonfly.
Two hundred and fifty million year old fossils have revealed that the families of modern day species were present back then, and even these had descended from ancestors that pre-dated them by another fifty million years.
Dragonflies, along with the damselflies, belong to the Odonata, meaning 'toothed jaw'. Dragonflies tend to be large and more stoutly built, than the smaller more delicate damselflies. Perhaps the most obvious physiological difference is that dragonflies always rest with their wings fully open and damselflies with their wings closed, or at the most only partially open. And creatures of perfection they certainly are.
Even as aquatic nymphs, they are exquisitely adapted hunters of the pond, lake, river and stream. Some perhaps, might not be given to use such superlatives to describe these dun-coloured, bug-eyed and gangly-legged denizens of the weedy depths, so very different as they are from their more widely appreciated adults, but for the simple functions of the predator of the wide range of aquatic invertebrates and occasional tadpoles and small fish, they are, in their own way, stunningly equipped. They do not hunt with speed and pursuit, but by ambush, hidden away amongst the bottom silt or submerged foliage. They attack with a highly evolved lower lip, which consists of a double hinged (one to fold it in half and one to tuck it beneath the animals head) appendage, armed with a pair of sharp fangs. This can be struck out with such speed that if the prey is not captured in the first instance, there would still be time for one or two more attempts.
The development from nymph to adult is a fascinating process. Depending on species, it can take between one and three years, of growing and moulting,after hatching from its water-borne egg. When ready to complete its journey into adulthood, the nymph will climb from the water, by means of a stem or leaf emerging from beneath the surface, or in some instances by climbing up banks or onto nearby terrestrial vegetation. Once firmly attached, the larval skin splits just behind the head and the fully formed adult within hauls itself out. This whole process takes at least an hour, before the wings expand and harden and for the insect to be able move. This being such a vulnerable time, emergence usually takes place at night or very early in the morning.
The resulting adults are creatures that cannot fail to entertain and enthral. Huge compound eyes give them superb vision, essential for capturing insect prey on the wing, which for the large species will even include other dragonflies. Two pairs of long wings are attached to strong thoracic muscles, able to twist for amazing agility - those dashing assaults on unwary prey, or clattering confrontations and territorial disputes with rival males. They can also, in the case of the larger species, allow speeds of more the thirty kilometres an hour (around eighteen mph) to be achieved.
There are thirty-eight breeding species of dragonfly and damselfly at large in Britain and several others that occur as vagrants. From this total, Essex does rather well, with twenty three species breeding in the county. This includes the awesome and beautiful emperor dragonfly, Britain's largest species with a wingspan of some ten centimetres and bright red male ruddy and common darters (females are a duller yellow-brown), diminutive but vibrantly coloured. There are the vivid blue azure and common blue damselflies and the simply stunning banded demoiselle - butterfly-bounding, iridescent jewels of the riverbank. And there is also the national scarcity of the scare emerald damselfly, once thought extinct in Britain until its rediscovery among the marshlands of South Essex.
These are insects that help make the summer. There is perhaps a July peak, in terms of the number species active, but the later weeks of the season sees some of our most spectacular dragonflies on the wing, with the rusty-winged brown hawker patrolling the pond waters and colourful and equally as impressive southern hawker, an insect with a decidedly inquisitive nature, sometimes allowing for close and exciting views. The Odonata year actually extends from the last days of April, with the appearance of the first large red damselflies, and on into the autumn, with migrant hawkers and common darters still about in October, with the latter species sometimes into November.
The dragonflies and damselflies are indeed things of stunning perfection and a number are thankfully numerous and widely distributed enough for any of us to be able relish in an encounter with them, and in a variety of wetland habitats. They exhibit a wonderful and exciting efficiency throughout their life cycles. These are ancient creatures that have stood a very rigorous test of time; even evolution must take heed of that old adage – if it ain't broke, don't fix it!
Essex breeding species
References and further reading
Benton, T. (2007) The Dragonflies of Essex. Wimbish: Lopinga Books
Brooks, S. (1999) Field Guide to the Dragonflies and Damselflies of Great Britain and Ireland. Hook: British Wildlife Publishing.
Meadowfield Nature Study Centre.
Church Road, Hockley, Essex SS5 4SS www.meadowfield.org.uk
(see also the Healthy Life Essex article : "Dragonflies a photographic study by Daniel Bridge")