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Aeshna cyanea (Muller) Souther n hawker
Description A. cyanea is a large hawker dragonfly in which the coloration and pattern of
body marldngs are similar to A. juncea, A. mixta and Brachytron pratense. Both
sexes of A. cyanea can be distinguished from the other three species by the
presence of two broad bands on the dorsal surface of abdominal segments 9
and 10 — blue in males, green in females. The antehumeral stripes are broad,
unlike those of A. juncea and A. mixta in which they are thinner or absent
altogether. These stripes and the two broad bands on either side of the thorax
are also much greener than in A. juncea and A. mixta, in which they are yellow.
The larger paired spots on the dorsal surface of abdominal segments 2-7 are
green in mature males, but blue in the other three species. A. cyanea lacks the
very hairy thorax of B. pratense, and its pterostigmata are not as elongated. It is
also much larger. In female A. cyanea, yellowish green replaces the blue
coloration of males.
Habitat A. cyanea breeds in mesotrophic ponds, lakes, canals and ditches. It is a
frequent visitor to garden ponds in southern Britain. It is restricted to lower
altitudes than A. juncea.
Breeding biology Males of A. cyanea are territorial. In Britain the highest steady density is about
2 per 100 m of water's edge but, elsewhere in Europe, higher densities have
been recorded (Poethke 1988). Small ponds may have only a single male at
any one time, but dozens, even hundreds, of larvae may emerge from it
(Merritt 1983b; Gaunt 1984). A succession of different males will occupy the
same pond in the course of the same day. The length of each visit depends on
the number present in the area: the more there are, the more frequent and
shorter will be their visits. The total amount of time spent by the pond
depends on air temperature (Kaiser 1974). Unlike most other British
dragonflies, it hunts quite late in the evening, and even when it is raining.
Copulation takes place away from water and lasts for up to two hours. Females
insert their eggs into vegetation by the water's edge, including dead wood,
and also into moss and bare soil. Females often oviposit in the evening and in
poor weather. Diapause occurs in the egg stage, and the larvae usually take
two or three years to develop. Emergence sites vary from tall marginal
vegetation to wooden posts, trunks of bushes and even the vertical concrete
walls of small reservoir tanks.
Flight periods A. cyanea is on the wing from early July to early October. It may be seen with
many other species such as A. grandis, Anax imperator, Libellula depressa,
Sympetrum striolatum, and the common damselflies.
Status and distribution
European and world
distribution
A. cyanea is found commonly in southern Britain, less so in northern England.
Sélys-Longchamps (1846) listed it from Scotland, but its first fully documented
record was in 1886 when it was discovered at Tayvallich, Kintyre. It still breeds
near there today Its rarity in Scotland is probably due partly to a climåtic
factor in view of the species' European distribution. Its absence from the
uplands of north Wales can probably be explained by a lack of suitable
habitat, and this may have blocked its spread into Anglesey and the Lleyn
peninsula. The only known record from Ireland is of a single female found in
Cork city on 17 October 1988 by K G M Bond. It was picked up dead, after a
night in which Saharan dust fell on the city (Bond 1989). It has been deposited
in the National Museum, Dublin.
A. cyanea is found from the Iberian peninsula and the western Mediterranean
to southern Scandinavia and east to the Caucasus. It is absent from the
southern Balkans.
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