| We have twenty-seven species of dragonflies and eighteen species
of damselflies in Britain. Damselflies resemble dragonflies, but are
smaller and more slender, and rest with their wings folded, whereas dragonflies
rest with their wings held out to the sides. Dragonflies are much the stronger
flyers reaching speeds of over 30 miles per hour. Both dragonflies and
damselflies have aquatic larvae, or nymphs, which often live in garden ponds, as well
as larger areas of wetland habitats, such as Blackburn Meadows. |
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During mating and egg laying, dragonflies or damselflies can be
seen flying in tandem.
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Adults have two pairs of large wings and a long, often very
brightly-coloured body. Some species place their
eggs on water plants near the surface (some species even crawl down stems
of emergent vegetation and into the water to deposit eggs below the
surface), while others simply scatter their eggs over the water. |
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| Although an adult dragonfly will often only live for about a month, it
may spend several years as a larva, eating other small aquatic animals,
including tadpoles and even small fish, as well as invertebrates. It
catches these by shooting out a set of modified jaws, called a mask,
so called because it folds back to cover the lower part of the face. It then
injects digestive fluids into its prey and sucks the juices out. Damselfly nymphs
are smaller, slimmer, and have three appendages at the rear,
which contain gills. |
Dragonfly eggs may hatch in as little as a month, or may
lie dormant until the following spring.
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Despite an old folklore tale that a dragonfly would sew up the mouth
of anyone who told a lie, no-one has ever had their mouth sewn up for
telling this particular lie, as dragonflies are completely harmless to humans.
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When the time comes for the nymph to metamorphose into an adult
dragonfly, it crawls up the stem of a plant
growing up out of the water. Once above the water surface, the skin on the back
of its head and thorax splits, and the adult starts to emerge. Once free of its
old larval skin, the newly emerged adult takes in air to swell its body and
pumps liquid into the veins of its wings to extend them from the creased
pre-emergent arrangement. This process can take several hours, and can be
the most dangerous few hours of the dragonfly's life, as it is vulnerable
to predators such as birds, and completely helpless until its wings have
extended and dried. |
| Dragonflies have very large compound eyes covering most of the surface of
the head, giving sharp eyesight to catch a prey of mosquitoes, gnats and
other small flying insects. Some species patrol an area, looking for their prey on
the wing, whilst others wait on a perch and dart out after passing insects. They
may hunt at considerable distances from the ponds and slow-moving rivers
where they breed. |
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Soon after hatching, the young
nymph moults its skin. It does this about ten more times throughout its growth.
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These animals are fascinating not just for their spectacular
appearance, powerful flight and voracious appetites, but also because they
have been around for 300 million years, appearing long before the
dinosaurs and surviving much longer than many other groups of animals. People
can help to protect these wonderful and beautiful mosquito-munching
insects by providing suitable breeding grounds for them in the form of garden ponds.
These should feature a variety of animal and plant life,
including emergent vegetation for the mature nymphs to climb when they are
ready to take to a life on the wing. |