Subarctic darner (Aeshna subarctica)

Like other members of the genus Aeshna, the Subarctic darner (Aeshna subarctica) is a large dragonfly with a long abdomen and a powerful flight ⁽²⁾. The thorax of this species is marked with broad blue to blue-green bands on the side, and the head is black with greenish eyes. Blue or yellow spots are present on some segments of the abdomen, but the abdomen is generally quite dark in appearance ⁽²⁾. The wings of the Subarctic darner are mainly clear ⁽²⁾.

The Subarctic darner is very similar in appearance to the common hawker (Aeshna juncea), which is predominantly brown with yellow markings on the thorax and blue on the abdomen. Distinguishing between the two species can be difficult and relies on close examination of the markings or the genitalia ^{(2) (3)}. In general, the Subarctic darner tends to be slightly smaller and paler, and also lacks the yellow spot behind the eye which is present on the common hawker ^{(2) (3)}. The leading edge of the Subarctic darner’s wing also tends to be brown rather than yellow ⁽³⁾.

Like other dragonfly species, the Subarctic darner has a complex lifecycle which includes a fully aquatic larval stage ⁽²⁾. As larvae or ‘nymphs’, dragonflies are effective sit-and-wait predators with the fascinating feature of being able to fire out the lower portion of the mouth, known as the ‘mask’, in order to grasp passing prey ^{(2) (7)}. As well as being able to walk, dragonfly larvae are able to move through the water by jet propulsion, expelling water from a specialised rectal chamber to propel themselves along ⁽²⁾.

The total length of time spent in the larval stage varies between dragonfly species, with some species spending a few months and others several years as a larva ⁽²⁾. The larva undergoes several moults before finally emerging from the water as the readily recognisable adult dragonfly ^{(2) (7)}. The adult Subarctic darner is active between July and September ⁽²⁾.

Dragonflies are skilled aerial predators, typically feeding on small insects caught on the wing ^{(2) (7)}. When not in flight, most members of the genus Aeshna tend to rest in a hanging position, rather than flat like other species of dragonfly ⁽²⁾.

An uncommon species, the Subarctic darner can be found in the north-east of Europe, and in similar habitats but at higher altitudes in central Europe ⁽³⁾. It has also been recorded in Russia and Kazakhstan, as well as in North America ^{(4) (5) (6)}.

The Subarctic darner inhabits bogs and moorland pools where it requires the presence of Sphagnum moss ⁽²⁾.

The Subarctic darner has not yet been globally assessed, but is classified as Near Threatened (NT) on the IUCN Mediterranean Red List ⁽¹⁾.

The Subarctic darner is thought to be generally uncommon across its range and, as with other species of dragonfly, it is facing a number of threats ⁽⁸⁾. Many species are sensitive to the degradation of their breeding grounds, with drainage for agriculture, urbanisation and pollution all impacting on freshwater habitats ⁽⁸⁾.

Global warming is one of the major future threats to dragonflies such as the Subarctic darner, causing species’ ranges to shift northwards and subsequently reducing the amount of available habitat ⁽⁸⁾. 

There are currently no known specific conservation actions targeting the Subarctic darner, although this species may benefit from general plans to conserve dragonflies in the Mediterranean region. Plans in this region include careful monitoring to provide detailed information on dragonfly populations and better protection of freshwater habitats ⁽⁸⁾.

Find out more about the conservation of the Subarctic darner and other dragonfly species:

• Riservato, E. et al. (2009) The Status and Distribution of Dragonflies of the Mediterranean Basin. IUCN, Gland, Switzerland and Malaga, Spain:
  http://cmsdata.iucn.org/downloads/mediterranean_dragonflies_en_web.pdf

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Abdomen

In arthropods (crustaceans, insects and arachnids) the abdomen is the hind region of the body, which is usually segmented to a degree (but not visibly in most spiders). In crustacea (such as crabs), some of the limbs attach to the abdomen; in insects the limbs are attached to the thorax (the part of the body nearest to the head) and not the abdomen.

Genus

A category used in taxonomy, which is below ‘family’ and above ‘species’. A genus tends to contain species that have characteristics in common. The genus forms the first part of a ‘binomial’ Latin species name; the second part is the specific name.

Larva

Immature stage in an animal’s lifecycle, after it hatches from an egg and before it changes into the adult form. Larvae are typically very different in appearance to adults; they are able to feed and move around but are usually unable to reproduce.

Moult

In insects, a stage of growth whereby the hard outer layer of the body (the exoskeleton) is shed and the body becomes larger.

Nymph

Stage of insect development, similar in appearance to the adult but sexually immature and without wings. The adult form is reached via a series of moults, and the wings develop externally as the nymph grows.

Thorax

Part of the body located between the head and the abdomen in animals. In insects, the three segments between the head and the abdomen, each of which has a pair of legs.

1. IUCN Mediterranean Red List (November, 2011)
   http://www.iucnredlist.org/initiatives/mediterranean
2. Gibbons, B. (1986) Dragonflies and Damselflies of Britain and Northern Europe. Hamlyn Limited, London.
3. DragonflyPix - Bog hawker (November, 2011)
   http://www.dragonflypix.com/speciespages/aeshna_subarctica.html
4. Bernard, R. and Kosterin, O.E. (2010) Biogeographical and ecological description of the odonata of eastern Vasyugan Plain, west Siberia, Russia. Odonatologica, 39(1): 1-28.
5. Chaplina, I.A., Dumont, H.J., Haritonov, A.Y. and Popova, O.N. (2007) A review of the odonata of Kazakhstan. Odonatologica, 36(4): 349-364.
6. DuBois, R.B., Johnson, R. and Putz, S. (1999) Aeshna subarctica (Odonata: Aeshnidae) in northwestern Wisconsin. Great LakesEntomologist, 32: 29-31.
7. O’Toole, C. (2002) The New Encyclopedia of Insects and their Allies. Oxford University Press, Oxford.
8. Riservato, E. et al. (2009) The Status and Distribution of Dragonflies of the Mediterranean Basin. IUCN, Gland, Switzerland and Malaga, Spain. Available at:
   http://cmsdata.iucn.org/downloads/mediterranean_dragonflies_en_web.pdf