Common Bluetail - Ischnura elegans

Scientific Name: Ischnura elegans.

English Name: Common Bluetail or Bluetailed Damselfly.

French Name: L'Agrion élégant (='the elegant blue damselfly').

5 Key Characters:
  • pterostigmas (the opaque marks near the tip of the wing) is bicolored (black and white).
  • male abdominal segment 8 is sky blue, all the others are bronze black on top, blue below.
  • fairly large and robust for a blue damselfly (30 - 34 mm long).
  • young males are green rather than blue.
  • females can be very like males or lilac, grey brown, dull green, reddish, greyish orange or pink rather than blue, sometimes going very dark with age.
Lookalikes: Redeyes Erythromma spp, which have red eyes, not blue and the blue tail light is on abdominal segments 9 - 10, not 8 i.e. right on the tip. Redeyes don't have bicolored pterostigmas. Small Bluetail I. pumilo, a smaller species, which has the blue tail light on segment 9, extending slightly into segment 8 (females lack it altogether) and pterostigmas that are larger on the forewing than the hind.

Habitat: Sunny still or slow flowing water, even if brackish or moderately polluted (plan d'eau of all sorts, natural watercourses, canals).

Flight Period: April-May-June-July-August-September-October-November. The species will fly in lower air temperatures than other species.

Status: Ubiquitous and common. Usually the most abundant species at eutrophic sites (water that is polluted with high levels of organic matter).

Photographed by Loire Valley Nature:

Photographs numbered from left to right and top to bottom. All photos will enlarge in a new window if you click on them. 1 - 2 young female of the form rufescens-obsoleta on the Claise River, Preuilly, in May. Her thorax will darken to greenish grey brown with age. Note this form has no black humeral stripe on the side of the thorax. 3 a young violet female in improved pasture in the Brenne, May. She will go blue with age. 4 a female of the form infuscans. She may go greener with age. These are much rarer in the population than the regular blue/green form and often do not mate. 5 mating pair (male above, female below). 6 - 7 male captured by a Robberfly Asilidae in the Brenne, May.8 Probable I. elegans exuviae (larval case) on Iris pseudacorus on the banks of the Claise River, Preuilly-sur-Claise, May.

No comments:

Post a Comment