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THE DOWNY EMERALD DRAGONFLY IN CUMBRIA
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We
are fortunate in Cumbria to have a few reasonably strong populations
of the scarce Downy Emerald dragonfly. Most English colonies
are found in the south-east from Dorset to Kent. Otherwise
the strongest populations are in Glen Affric in Scotland or
Killarney in Ireland.
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In
the South-east of England typical habitat is found on ponds
and lakes on large country estates. In Cumbria it is associated
with tarns in old woodland. Indeed, the species probably occupies
some of the most beautiful sites that you could hope to find
for a spot of dragonfly watching (see above and below)!
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As
one of the early species, the Downy Emerald is usually on
the wing in Cumbria from mid-May. Apart from the damselflies,
the most likely species to be around at this time is the Four-spotted
Chaser.
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It's
not the easiest of species to identify as it rarely comes
to rest in accessible places and identification in flight
is the only way. It is most likely to be encountered in ones
and twos at the tarn edges as a medium sized, bronze coloured
dragonfly. Males patrol in a low fast flight, pausing to hover
at intervals. As the species turns towards you the most striking
feature can become apparent....the bright green eyes. A pair
of binoculars will help with this feature, but are of little
use in picking out the hairy abdomen from which the species
gets its name. Even less likely to be visible is the yoga-like
way it places its front legs behind its head when hovering!
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After
emerging from the larval state the species spends ten days
or so maturing in the woodland before returning to water.
Even then, males spend much of their time feeding and resting
in trees, only visiting the waters edge for 30 minute spells
to look for a mating opportunity. In this way the best sunny
inlets are used on a time-share basis by several males.
Females are more likely to be seen ovipositing early and
late in the day, thereby evading the attentions of the males.
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The
key habitat requirement for the species seems to be
undecomposed leaf litter (the larva of other species
prefer more fibrous, decomposed, muddy litter or growing
vegetation). Oak and Beech, which are so typical of
Lakeland woods, are notoriously slow to decompose and
may help the species to survive here. The larvae are
amongst the slowest of all dragonflies to develop, taking
three years or more to reach maturity in the south.
In the colder waters of the Lake District it is possible
that they may take even longer.
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