Dragonfly Guide

Ischnura

Charpentier, 1840

Ischnura is a genus of damselflies known as forktails in the family Coenagrionidae. Forktails are distributed worldwide, including various oceanic islands. The males have a forked projection at the tip of the abdomen which gives the group their common name.

Identification Small delicate damselflies. The males are easily recognised by their contrasting blue 'tail-light' marking at the end of the abdomen. The abdomen is otherwise largely black or bronze-black dorsally, with the underside of S3-S& yellow.

Males have a bicoloured pterostigma in the forewing. The inner part is dark grey while the outer part is whitish. At the base of the ovipositor the females usually have a small vulvar spine on the underside of S8.

Separation from other genera

The dark abdomen with blue 'tail-light' may recall dark-bodied Coenagrion or Erythromma species, but both these have unicoloured dark pterostigmas. In Coenagrion S2 is mainly blue, and dark Erythromma have conspicuous red eyes. The vulvar spine feature of the Ischnura is shared only with Enallagma females, however these differ in their abdominal markings.

Behaviour

Females of Ischnura oviposit alone, unlike other small damselflies who often do thisin tandem. After emergence, many adults remain close to water, often creating high proportions of mating pairs and tenerals at a site.

Distribution

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Distribution map. Data from gbif.org

Sources

  • Field guide to the dragonflies of Britain and Europe, Klaas-Douwe B Dijkstra.

  • Wikipedia