The Norsey Wood Society works closely with Basildon Borough Council, the owners of Norsey Wood Nature Reserve, an ancient woodland which is also
a Site of Special Scientific Interest on the edge of Billericay in Essex, UK
Odonata
Dragonflies and Damselflies of Norsey Wood
Overview
There are 42 resident breeding species of dragonfly and damselfly (sub-orders of the Odonata family) in the British Isles. These are sometimes augmented by migrating or windborne species from the mainland continent, and due to our changing climate, some even stay to breed. Dragonflies are chunky and strong flying insects and when settled hold their two pairs of wings at right angles to their body whereas damselflies are diminutive in size, weaker flyers, and hold their two pairs of wings parallel to their abdomen when perched. Since 1978, 15 species have been recorded within, or along the edges, of the Wood. This Link will take you to those.
Prehistoric Ancestry
The dragonfly and damselfly insect group are ancient; having evolved in prehistoric times, and have hardly changed since. This is proven by the fossil record.
Life-cycle
The life-cycle is simpler than that of butterflies by missing out the chrysalis stage. An adult lays a series of eggs on an aquatic plant beneath the water surface. These hatch out as larvae and then a year or more later, usually in the early morning, emerge and climb out onto a reed, or a stem of vegetation, to undergo the transitional stage from larvae to adult. It is a wonder how the resultant adult is so much larger than the capsule that contained the larvae but as it emerges it pumps fluids into its body and the veins of its wings that greatly increases its size. This is the vulnerable period when they wait for the sun to dry and harden them. Ants and spiders will predate them, and Reed Warblers, House Sparrows and Magpies will pick them off to feed to their nestlings! The food chain is a cruel mistress!
Lifestyle
Dragonflies are powerful flyers and can roam many kilometres away from the water bodies from where they emerged. In contrast, damselflies are weak flyers and rely on rising air and the wind to disperse them across the countryside. Both start life in ponds and waterways. Dragonfly larvae are ferocious predators, living on other dragonfly and damselfly larvae, tadpoles, young newts and any other aquatic underwater insects they can catch and consume. Dragonfly larvae, depending on the species, need to remain underwater from two to four years during which time they undergo various moults as they grow larger and eventually measure, depending on the species, from 17mm to 50mm in length.
Conversely, damselfly larvae are very small and live underwater for a year before emerging. They then fly jerkily and low over the water surface, looking for mating opportunities and alighting on lily pads to sunbathe.
But these flying jewels of an ancient lineage, after spending so long underwater, live but for a few weeks once they have emerged.
Dragonflies may cruise at 10mph and are capable of bursts of speeds of up to 30mph. They can even fly backwards!
Dragonflies and damselflies catch and eat their aerial prey by scooping them in flight by using their six legs as a ‘basket net’. Dragonflies are ferocious hunters of other aerial insects - gnats, mosquitoes, flies, bees, moths and even butterflies. Hobbies augment their diet by catching the higher flying dragonflies and eating them on the wing.
The dragonflies and damselflies as a group, are on the wing from late-April to late-September and the various species have a specific time of emergence – This Link
will download a pdf file that gives dates for the various species in the Wood.
Identification
A classic field guide for identification is ‘Britain’s Dragonflies’ by Smallshire and Swash in the WILDGuides series. The Society devoted to dragonflies is the ‘British Dragonfly Society’. They have a website App available that is compatible with Android, iOS, laptops and most tablets.
In hot sunny weather they are so active that studying detail can be very difficult. However, wait for the sun to go in behind a cloud and they will often settle, especially the damselflies. Damselflies are mostly solar powered! Look for them where the sun shines through the woodland canopy onto the pond below! There are medium power close focusing binoculars on the market that let one study the intricate detail from several feet away. Identification is usually accurately clinched when at least three diagnostic details are noted. Learning the names of the various body parts of the insect is fundamental in leading to the correct identification. That and combining behaviour clues will further help the situation.
The English names of the dragonflies that have been recorded for the Wood describe their hunting techniques, namely:-
Chasers, Darters, Hawkers and Skimmers.
Male and females of a dragonfly and damselfly species, although structurally similar, are usually coloured differently.
Taking close-up photographs out in the field and identifying them later at home is also an efficient method. Record shots of unusual species encountered will be invaluable to the Woodland Warden. Dragonflies in particular will often return to the same look-out post after hunting prey. A garden pond is good for studying dragonflies and damselflies as it will be visited by a succession of species over time. The breeding species will change as the pond becomes mature and the water quality changes. They have no preference for the type of vegetation surrounding the pond. Odonata occasioned upon that lack vibrant colours are termed as ‘tenerals’. Please see below for an explanation.
Sometimes you may have seen a chunky sized dragonfly flying around your legs. This is usually a Southern Hawker that is feasting on the insects that are being disturbed as you move along!
Technical Terms
Odonata– The group name for both the dragonfly and damselfly sub-families.
Demoiselle
– The name given to the larger and more spectacular damselfly species.
Exuviae
– The dry skin left low down on the vegetation after a dragonfly/damselfly has emerged.
Teneral
- A freshly emerged dragonfly/damselfly that still needs time to acquire its true colours. This can take from a few hours to a week depending on the weather and the species. Confident identification can be problematic at this stage.
For more images of these beautiful creatures, have a look through the pictures on the image page.