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Description
Breeding biology
Status and distribution
Coenagrion puella (Linnaeus) Azure damselfly
C. puella males are pale sky-blue with black markings. The blue antehumeral
stripés on the thorax are narrower than those on Enallagma cyathigerum, the
other common blue damselfly, and the black marking on segment 2 of the
abdomen is quite different, being typically a thin unstalked U-shape. Like
other Coenagnbn species, C. puella has two short, thick black lines on the side
of the thorax in both sexes, whereas the similar E. cyathigerum has only one
(Longfield 1949a; Welstead & Welstead 1983b). Females can occur in one of
several forms: one is dark with greenish markings on the thorax and abdomen,
and the other forms have blue markings which can be quite extensive and
closely resemble C. pulchellum females, from which they can be distinguished
by the shape of the hind margin of the pronotum, which is not tri-lobed as in C.
pulchellum.
Habitat C. puella is found in a very wide range of habitats in Britain and Ireland,
including garden ponds, lakes, streams and rivers, peaty pools and ditches. It
is often seen in large numbers in early summer, frequently settling on floating
weed or algae, and in nearby glades and meadows.
C. puella is not territorial, but there is evidence that its density is regulated to
some extent by its behaviour, which includes threat displays (Moore 1995).
Copulation is prolonged and only occurs on warm sunny days. The mating
success of females depends on their length of life: the rate of egg laying and
clutch size are of lesser importance in C. puella. Oviposition takes place in
tandem, with the female inserting her eggs into the tissues of floating and
submerged plants, and sometimes becoming completely submerged. Larval
development usually takes one year, but can take two (Parr 1970). Emergence
occurs in the morning on emergent vegetation, including the flower spikes of
pondweeds in the centre of ponds, with the females emerging a day or two
earlier than males and being less likely to return to their emergence sites than
males (Banks & Thompson 1985). The mean lifespan of mature adults is
between live and six days (Banks & Thompson 1985). Grazing animals around
ponds can reduce breeding success greatly, because they reduce the
numbers of emergence sites and make those which are left more vulnerable to
predation by birds. Adult C. puella roost on rather broader stems than Ischnura
elegans, but less broad ones than E. cyathigerum (Askew 1982), with just their
eyes visible on either side, from the front. This is a defence mechanism: they
will move round the stem as danger approaches.
Flight periods C. puella is on the wing from mid-May to the end of August, but is most
common in early summer. It can be seen with almost all other British and Irish
species that liare its geographical range.
C. puella breeds widely and extremely commonly throughout England and
Wales, the lowlands of central and southern Scotland, and most of Ireland. Its
absence from parts of central-southern England and from parts of the Fens is
due to the lack of water bodies in these areas because of, respectively, the
porous chalk substrate and the loss of wetlands through agricultural pressures.
C. puella is seldom found at moderate to high altitudes, and is absent from the
uplands of north Wales, the northern Pennines, and much of Scotland.
European and world C. puella is found commonly throughout much of Europe, though it is absent
distribution from most of Scandinavia. Its range extends east to the Caspian Sea.
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