Blue-tailed Damselfly – Ischnura elegans

European common name: Common Bluetail

The Blue-tailed Damselfly – Ischnura elegans, is an abundant damselfly, and the female has distinct colour forms at different stages of its life-cycle.


CoenagrionidaeBlue or red Damselflies

Abundant damselfly – the most common in Bedfordshire. The abdomen is predominately black, with a distinctive coloured ‘tail-light’ on segment 8 that makes them easy to spot, especially as they move.

Males are blue, with thin shoulder stripes on the thorax and a black abdomen. The tail-light is blue, matching the thorax. Immature males may appear greenish blue.

Females are polymorphic and occur in multiple colour forms. There are two separate immature colour phases (violacea and rufescens) that last only a few days, but the mature female’s final colouring is determined by genetic factors. In total there are 5 distinct colour forms of the female (2 immature, 3 mature), making identification more difficult.

The female shares the tail-light, but its colour is dependent on the colour phase, and may be blue, violet, green or brown.

The development of the different female colour forms is summarised in the table below:

Immature typeMatures as
violaceaeither typica or infuscans

Overall length: 30 – 34 mm
Wings: 14 – 20 mm

There are several other broadly similar species that might cause some confusion:

  • White-legged Damselfly – Platycnemis pennipes
    Has paler colouring, white legs, and the black is less extensive on the dorsal surface of the abdomen. Has four, similarly sized, shoulder stripes, rather than two.
  • Azure Damselfly – Coenagrion puella
    Has a more extensively blue abdomen and lacks the ‘tail-light’ of the Blue-tailed. The male features a characteristic ‘U’ marking.
  • Common Blue Damselfly – Enallagma cyathigerum
    ‘Mushroom’ or ‘lollipop’ shaped marking on segment 2 of the male. Male and female have broader shoulder stripes on the thorax than the Blue-tailed, and with more extensive blue on the abdomen.
  • Red-eyed Damselfly – Erythromma najas
    Male: Is larger, with very obviously red eyes. Dorsal surface of the abdomen mostly black except for a prominent blue ‘tail-light’. All black thorax and no shoulder stripes from above.
    Female: Is larger, with green or reddish green eyes. Dorsal surface of the abdomen more extensively black. All black thorax and incomplete shoulder stripes from above.
  • Small Red-eyed Damselfly – Erythromma viridulum
    Male: Is smaller, with very obviously red eyes. Dorsal surface of the abdomen mostly black except for a prominent blue ‘tail-light’. Almost all black thorax but with a single narrow shoulder stripe from above.
    Female: Is smaller, with green eyes. Dorsal surface of the abdomen more extensively black. All blue thorax with narrow green shoulder stripe from above.

Found almost anywhere where there is water, and is common around most rivers and ponds. More tolerant of polluted waters than most Odonata, and often the only species visible in poor weather.

Very common throughout Bedfordshire and is likely to be found almost anywhere where there is water. 

Visible between early May and late September, peaking in June and July.

Blue-tailed Damselfly - Ischnura elegans Male, River Great Ouse between Kempston and Bromham.
Male Blue-tailed Damselfly – Ischnura elegans
Blue-tailed Damselfly - Ischnura elegans Female, Felmersham NR. This female is of the 'rufescens-obsoleta' form.
Female Blue-tailed Damselfly – Ischnura elegans 'rufescens-obsoleta' form

External links for Blue-tailed Damselfly – Ischnura elegans:
British Dragonfly Society | Wikipedia