Aeshna cyanea

Other common names: Blue hawker

Adult A large hawker with a green thorax and black abdomen (dark brown in mature females). Two black stripes are present on the sides of the thorax, one bisecting it completely and a shorter stripe that terminates halfway (see main photo). A defining feature is the pair of broad, oval antehuneral stripes on the front of the thorax, which are wider than the surrounding dark area. These are green in mature adults and yellowish in teneral specimens, and larger in males than females. Male tail appendages curve downwards in a 'bird's-head' shape. The upperside of the abdomen has paired green spots (blue-grey in newly-emerged adults). Spots on the underside are green in females and blue in mature males; occasionally the upperside markings are pale blue. Mature males have a blue 'tail light' on

abdominal segments 8-10 (the final segments). The pleurostigma is short and rectangular,

about 3mm long and 1.5mm wide.

Larva: Long, torpedo-shaped larva with eyes that are broader than long. Lateral spines occur on segments 6-9; that on segment 9 reaches at least as far as the centre of segment 10. The larval epiproct has a shallowly concave shape.

Detail of the larval epiproct.

Similar species: The southern hawker differs from other Aeshna species in possessing 3-6 cells in the anal triangle of the hindwing, and the male's lack of a short 'tooth ridge' on the final abdominal segment. Patterning distinguishes it from other European dragonflies Larvae can be distinguished by the long labial mask, greater than 3.5 times as long as broad at the base and by the shape of the epiproct. The very similar migrant hawker (Aeshna mixta) can be distinguished primarily by its much smaller size (below 38 mm). Larvae are longer, more slender and more rounded than chaser, darter, skimmer and emerald larvae. Larval emperors (genus Anax) have rounder heads, and eyes that are longer than they are broad.

Larval labial mask.

HABITAT

Shaded, small, still waterbodies with leaf litter substrates. They can be common in urban areas and in heavily forested regions, frequently using habitats unsuitable for other dragonflies such as garden ponds and forest pools. Larvae inhabit coarse debris where they can be very abundant, migrating to deeper water in winter.

BEHAVIOUR

Adult males are territorial, aggressively defending their hunting and breeding grounds against other males. Characteristically, males follow an erratic rather than a fixed patrol route, and are often most active around dawn and dusk. The abdomen may be held curving downwards in flight. In suitable habitat, forest clearings may be used as foraging grounds.

Breeding behaviour: Females oviposit alone, not in tandem with a male. Eggs are laid at the edge of waterbodies, often outside the water in rotting wood.

Emergence: Larvae typically emerge on upright stems protruding from the water, at a height of 0.3-0.4 m. Emergence rates peak in July, but may continue into September.

Flight season: June through to autumn, occasionally into November. Most typical of July and August; emergence

can rarely occur as early as late April..

Female southern hawker ovipositing at the edge of a pond.

Newly emerged

southern hawker,

Lincolnshire,

United Kingdom

REFERENCES

Dijkstra, K-D.B. and Lewington, R. 2006 Field Guide to the Dragonflies of Britain and Europe British Wildlife Publishing: 320 pp

Cham, S. 2007 Field Guide to the larvae and exuviae of British Dragonflies Volume 1: Dragonflies (Anisopera) The British Dragonfly Society: 76 pp.

British Dragonfly Society: Aeshna cyanea - Southern Hawker

Aeshna cyanea nymph with extended labial mask. Note the length of the labium.