Dragonflies are among
the most ancient of living creatures.
From fossil records
we know that these amazing insects were flying some 300 million
years ago, before even dinosaurs roamed the earth.
Over the centuries
an extensive folklore has seen dragonflies revered in some
cultures as symbols of strength, regeneration and pure water, and
feared in others as shamanistic creatures with supernatural powers.
White-legged damselfly at
Alderney wetlands, 2003
However you might look upon them, it is true
that they are a reliable indicator of good water quality, and recent
research finds they can be useful for the biological control of
mosquitoes. They're also fascinating, beautiful and quite harmless
- they have no sting and will not attack or bite.
It's not all good news, however. Forty
years ago the UK boasted 42 breeding species of dragonfly. Three
of these are now extinct. The Orange-spotted Emerald was lost when
a sewage spill polluted its last remaining breeding ground; the Norfolk
Damselfly similarly surrended to local pollution; and the Dainty
Damselfly was wiped out when its Essex habitat was flooded.
But thanks to a increasing awareness
of the dragonfly's plight, to our expanding knowledge of their needs and
conservation activity, several species are actually flourishing and
partnership projects are helping this trend in the Bourne Valley.
(Anisoptera) tend to be the larger of the two,
much for robust and more powerful fliers. The head is more spherical
and consists almost entirely of a huge pair of eyes. The front and
back wings are dissimilar in shape and are normally held open whilst the
dragonfly is at rest.
(Zygoptera) are very delicate, slender insects,
weak and fluttering in flight. The head is rectangular and large
eyes are positioned on either side, a bit like a hammerhead. The
front and back wings are the same shape and are normally held closed along
the abdomen when the damselfly is at rest.
Where to find
In Britain all dragonflies require permanent
water and can be found in almost any conceivable wetland habitat, from
ponds and lakes to canals, rivers, ditches and sphagnum bogs.
Dragonflies thrive in unpolluted water that
supports plenty of submerged and emergent vegetation. These provide
egg laying and emergence sites as well as shelter. Many species also
require some open water. They tend to prefer situations that are
open to sunlight with some shelter from strong winds.
Dragonflies are visual hunters and have
impressive vision being able to see in colour as well as ultraviolet light
and polarised light, which enables them to see reflections of light on
Their large compound eyes are made up of as
many as 30,000 facets or lenses (ommatidia). Those in the upper part
looking forward are usually larger and more numerous that those elsewhere
providing the area of best visual acuity. This is why dragonflies
usually approach prey from behind and below.
Dragonflies are usually most noticeable when
in flight, as the sunlight catches their wings and the iridescence on
their bodies. Sometimes they can be heard before they are seen when
their wings catch the vegetation.
Hawker Dragonflies can fly at 36km/hour and
Damselflies at 10km/hour.
Dragonflies are beautifully adapted for
flight, having powerful flight muscles and wings that move independently.
They are incredibly agile and manoeuvrable and are able to hover, fly
forwards, backwards, sideways and to rapidly change the direction and
speed of flight.
Both the larvae and adult dragonflies are
Adults feed on flying insects, especially
small flies, midges and mosquitoes. Some of the larger species, such
as the Emperor, will take butterflies and damselflies. Many species
consume their prey on the wing, but some damselflies and chasers tend to
rest while feeding.
Golden-ringed dragonfly in the
Dragonfly larvae are mostly ambush
predators, feeding on anything that is smaller than them such as
insect larvae, water fleas, snails, small fish and tadpoles.
They extend their modified lower lip (labium) at lightning speed and
impale prey on the sharp mandibles.
Their size and beauty make them
especially valuable subjects for research into insect behaviour
and ecology. They have played a significant role in some
cultures and they are increasingly being used as subjects for art
Dragonflies have aquatic larvae, which
generally rely on good water quality. Consequently they can
be used to make rapid assessments of water quality and indicate a
Over the last 40 years we have witnessed the
extinction of three species of dragonfly in the British Isles and at least
one third of the remainder are considered to be rare and localised.
The most significant threats appear to come
from habitat destruction and fragmentation, pollution, inappropriate
habitat management, alteration of site hydrology and the impacts of global
Dragonflies are worthy of conservation in
their own right, but their requirements for clean water and a mosaic of
habitats mean that if dragonflies are conserved so are many other
organisms. They can be used as a flagship not only for aquatic
habitats but also for the wider insect world.
Bourne Valley species
More than 20 species of dragonfly have been
recorded at the Bourne Valley SSSI, at least 18
with breeding evidence, and this reflects the variety of aquatic habitats
such as acidic bog pools and vegetated ponds, and terrestrial feeding
Click on images to enlarge
Keeled skimmer Orthetrum coerulescens
Golden-ringed damselfly Cordulegaster
Large Red damselfly Pyrrhosoma
Small red damselfly Ceriagrion
tenellum (nationally scarce)
Downy emerald Cordulia aenea
Black-tailed Skimmer Orthetrum
cancellatum (local species)
In 2003 student
Robert Aquilina carried out a study of local dragonflies,
comparing numbers and species at the lagoons & wetlands created at
Alderney (2000 & 2001) with more established ponds, pools and
stream sites in the valley:
In 2005 a new study by Andrew Brown (Bournemouth University) and
a colleague from the
Herpetological Conservation Trust collected data on the status
of Dorset's dragonflies, including those in the Bourne Valley.
at Bourne Valley SSSI
Common Darter (female)
on Bog Myrtle at Bourne Valley SSSI
Click on the
image to enlarge it
two Hawker dragonflies (probably Migrant Hawkers (Aeshna
mixta)) in a mating wheel on bulrushes at the new fishing
pond at Bourne Valley
Park in early October.
It's more usual to
see this sort of behaviour during late summer, rather than
Autumn. Is this another sign of climate change? Or
simply an effect of this year's exceptionally mild weather?
For amazing dragonfly &
damselfly photographs visit
Richard Ford's Digitalwildlife website
British Dragonfly Society
The Partnership acknowledges the BDS in
publishing much of the information on this page.