Jewels of the
Air
Have you seen any devil’s darning needles lately? How
about horse stingers? You almost certainly have - these are just two of
the many old country names for perhaps our most charismatic insects -
dragonflies and damselflies. For many, they are the essence of summer,
with their dashing flight and dazzling colours!
Both belong to the insect order known as Odonata,
meaning ‘toothed jaw’ - their mouth-parts are serrated. Many people
get confused between dragonflies and damselflies, but with a little
practice the two can be easily separated.
Dragonflies are generally significantly larger than
damselflies, with a body length of around 70mm (2.75 inches) and a
wingspan around 100mm (4 inches). When dragonflies land they keep their
wings held straight out, at right angles to the body and the eyes are very
large and ‘wrap-around’, dominating the face and joining on top of the
head. In contrast, most damselflies have a body just 30mm (1.25 inches)
long and a wingspan of 35mm (1.5 inches). When they land they hold their
wings together over their backs and the eyes are rather small and are also
widely spaced, perched on the ‘corners’ of the head.
Unlike butterflies, dragonflies and damselflies undergo
an ‘incomplete metamorphosis’ - they have no chrysalis or pupal stage.
The larvae (or 'nymphs') develop underwater. Most species live for one or
two years as nymphs, but some spend five years in the murky waters of a
pond before emerging into the summer sun as a winged adult.
Newly emerged from the egg, the larva is a miniature
replica of its parents, but without wings. Nymphs are ferocious predators,
able to capture prey at least as large as themselves, including a plethora
of other aquatic invertebrates, fish and even other nymphs! Being top pond
predators, they possess a powerful weapon, the labium or ‘mask’,
claimed by many to be the inspiration for jaws of the creature of the
famed Alien films. The nymph possesses a set of long piercing jaws,
set on the end of an extendible ‘arm’. When inactive, this fearsome
device is held retracted under the mouth parts, but if some luckless
creature gets too close, with explosive accuracy the mask is thrust
forwards, grabbing the prey, which is quickly devoured.
Thankfully, these miniature aliens are at most the
length of a thumb and quite harmless to us. However, could the same be
said for the one-metre wingspan giant Protodonata that flew some
325 million years ago? Flying when dinosaurs roamed the Earth, these are
considered to be the ancestors of our modern day dragonflies.
On still, warm mornings from late April through to
October, billions of larvae jostle for position before climbing water
plants, emerging from ponds, lakes and rivers throughout the country.
Having hauled up to a safe distance above the water’s surface, the
larvae sheds their skins. As the first rays of sun fall, the wings start
to harden and take their familiar shape. In contrast to the many months or
years spent living under water, the brilliantly coloured, winged adult
will survive only a few brief weeks!
Currently, about 5,500 species have been ‘catalogued’
world-wide, with more being discovered each year. The county of Kent plays
host to 30 of the UK’s 42 breeding species and has been visited by a
further four migrant species. Dragonflies and damselflies can be
encountered almost anywhere where water is found. However, few are able to
cope with highly enriched or polluted water and, as such, they are
useful indicators of good water quality.
Over the last 50 years, three species have become
extinct in the UK through habitat loss and pollution. Despite this, in
Kent the future is looking bright for 'devil's darning needles'. A species
previously thought extinct in Britain, the scarce emerald damselfly, was
rediscovered in the county in 1983 and very recently two species new to
the UK have started to breed.
So, whether budding Odonatologist or simply
someone who loves to marvel at nature’s creations, now is the time to
get down to your local pond and enjoy these fascinating creatures in their
finest hour.
Anyone wanting information on pond creation, one of the
easiest ways of conserving Dragonflies, should contact the KSCP.
Jason Mitchell,
Countryside Officer, Canterbury and Lower Stour
"Today I saw the dragonfly
come from the wells where he did lie.
An inner impulse rent the veil
of his old husk; from head to tail
came out clear plates of sapphire mail.
He dried his wings: like gauze they grew;
thro’ crofts and pastures wet with dew
A living flash of light he flew".
from The Lady of Shalott by Tennyson
