Nationally. P nymphula is one of our most common and widespread species but this
is not true of its status in Essex. The species inhabits a very wide variety of habitats in
Essex, from ditches in coastal marshes (though, in contrast with Ischnura elegans, for
example, it is not often found in brackish conditions) through to swiftly flowing streams
and rivers (such as the Ter and the Roman River), slower canals and rivers (the
Chelmer/Blackwater Navigation), farm ponds, and well-vegetated flooded pits (Kits
Pond, at Fingringhoe Wick). In view of this apparent adaptability, it is odd that the
species is comparatively localised in Essex. Since 1980 it has been recorded in twenty-
three out of a possible fifty-seven 10 km. squares in Essex, but in as many as twelve of
these it is represented by only single, apparently isolated colonies. It is sufficiently local
in Essex to justify special attention to conserve it where it occurs.
Ischnura elegans (Vander Linden, 1820) Blue-tailed Damselfly
This species, the commonest of all the Odonata in Essex, is distinguished, in its
'normal' form from the other common blue-and-black damselflies by its single clear
blue segment (segment 8) towards the posterior tip of the abdomen. The other
abdominal segments are almost completely black. Confusion can, however, arise from
the common occurrence of several different colour forms in the females. Form infuscans
has dull-brown instead of blue on segment 8, giving the impression of a uniformly dark
abdomen, whilst infuscans-obsoleta has the sides of the thorax rusty brown, and is
without thoracic stripes. To add to the confusion there are other colour variations which
are generally indicative of immature, or 'teneral' phases prior to the adoption of full
adult colouration. As with some of the other blue-and-black damselflies, it is advisable
for beginners to base their identification on males where this is possible.
The above-mentioned colour-forms are all common in Essex populations of /.
elegans. The species occurs commonly in the estuarine and coastal ditches, even in
strongly brackish borrow dykes, though less frequently when these are recently dredged,
and denuded of vegetation. It also occurs in ponds, ditches, flooded pits, reservoirs,
canals, rivers and even relatively swift-flowing streams, throughout the county. The
species does not appear to be 'territorial' as is Enallagma cyathigerum, and large
aggregations of individuals are often seen 'basking' on wide-leaved plants, such as
Water-lilies and Burdock. However, they do indulge in a curious 'chasing' behaviour,
sometimes involving four or five individuals. Pairs generally mate in or around
marginal vegetation, and the females usually oviposit singly. Individuals I have
observed generally alight on floating or emergent vegetation, and curve the abdomen
under the surface of the water to lay their eggs, presumably singly, in the stem or leaf
tissue of water plants. The adults prey on small flying invertebrates such as gnats, and
are themselves eaten by a wide variety of predators. I have observed a specimen of /.
elegans caught in flight by a wasp. Vespula rufa, which then settled on marginal
vegetation, quickly severing the abdomen (which fell to the ground) and consuming the
head and thorax of the damselfly. The latter was held in position in a 'cage' formed by
the legs, thorax, and up-curved abdomen of the wasp. In the coastal marshes they are
also commonly preyed upon by spiders, notably Araneus sp. The observed flight-period
since 1980 in Essex is from the second week in May through to the end of
September.
The historical record suggests that the species was always as widespread and
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