Aeshna juncea (Linne, 1758) Common Hawker
In some parts of Britain this species undoubtedly deserves its vernacular name, but
Essex is decidedly not one of these! Aeshna juncea is a wet heathland and moorland
species, widely distributed in Britain except East Anglia and the extreme south-east of
England, where there is little suitable habitat. A large hawker, patterned in a mosaic of
dark brown, yellow and blue or green, A. juncea is easily confused with Aeshna mixta or
Aeshna cyanea. The blue (in the male) or green (in the female) paired spots on the
abdominal segments remain separate on segments 9 and 10, whereas they are fused into
a band on A. cyanea. This character is quite easy to observe in the field, but
differentiation of A. juncea and A. mixta in the field can be much more difficult. Because
of the adoption of misleading (so far as our county is concerned) vernacular names, A.
mixta has often been mistaken for A. juncea, and so many field reports of the latter have
to be treated with some scepticism (see under A. mixta for further details on
differentiation of A. juncea and A. mixta).
Aeshna juncea appeared on none of the earlier lists for Essex, and Longfield (1949b)
did not list it as present in, or as having been recorded from, either of the Essex vice-
counties. She said it occurred on a few of the Surrey commons, but within the L.N.H.S.
boundary she believed it occurred sometimes as an immigrant. Available evidence
suggests this is its status in Essex today. Though there have been a few reported sightings
(G. Foott 1967, Fingringhoe Wick (B.R.C.): and 1953-8, Distillery Pond. Colchester
(C.E.M.)) from the east of the county, these are of doubtful validity. E. P. Ryan saw one
hawking over Wake Valley Pond in Epping Forest on 14th August, 1983 (pers. comm.).
Aeshna juncea is almost certainly not a breeding species in Essex, and probably never
has been.
Aeshna cyanea (Muller, 1764) Southern Hawker
This large, eye-catching hawker is one of our best known species. It is common and
widely distributed in the southern counties, becoming scarcer northwards. The large
apple-green stripes on the thorax (sometimes taken for 'eyes' by the uninitiated!) are
very distinctive, as these markings are much less in evidence on Aeshna mixta, the only
other common species with which A. cyanea could be confused. Aeshna cyanea is also
significantly larger than A. mixta, but the best field character for distinguishing the two
is that in A. cyanea the paired green or blue markings on each segment of the abdomen
are fused into bands on segments 9 and 10, whereas in A. mixta they remain separate
even on these hindmost segments of the abdomen. This feature also serves to
distinguish A. cyanea from a third very similar species, Aeshna juncea (for differences
between A. mixta and A. juncea see under A. mixta and also Appendix C).
Aeshna cyanea is a species most commonly met with singly, and often well-away from
its breeding sites. It hawks along a regular beat, which may be a disused railway cutting,
a woodland ride, a sheltered hedgerow, a coppice-clearing in woodland, or some similar
habitat where its insect prey is plentiful. It tends to fly lower than A. mixta, often closely
following the contours of trees or shrubs it encounters, and it will make detours to
examine unfamiliar objects - such as human observers! - which come within its field of
view. Unlike some other hawkers (e.g. Anax imperator), A. cyanea frequently settles for
considerable periods, usually choosing a perch in a sheltered, sunny spot. Mating often
69