Scarce Blue-tailed Damselfly - Ischnura pumilio

Adult size

Overall length: 26 - 31mm   Hindwing length: 14 -18mm

Distinguishing features

One of four species of damselflies which have an almost solid black abdomen and a blue ‘tail’ in males, but females lack this. They can be confused with Blue-tailed Damselfly though they are smaller and less robust looking. They therefore could be easily overlooked and under-recorded. Very localised distribution and nationally scarce.

Identification - for help with terms see glossary

Mature Males

Have thin blue antehumeral stripes, blue sides to thorax, a black abdomen and a small patch of blue covering the tip of segment 8 & all of segment 9, which seperates it from Blue-tailed Damlselfly which only has blue on segment 8.

Immature males

Have green antehumeral stripes, green sides to thorax.

Females

Females initially will be an immature aurantiaca phase in which eyes, thorax and abdomen is a stuning bright orange which cannot be confused with anything else and are can be the easiest way to determine the presence of the species. Mature females will change into a very dull brown/green thorax, will a black abdomen which, significantly unlike female Blue-tailed Damselflies will not have a blue ‘tail’.

Habitat

The Scarce Blue-tailed Damselfy is usually found in warm, shallow wetland sites such as bog pools or slow flowing water, fed by seepages and flushes. It appears to prefer early successional habitats with minimal vegetation, although some emergent plants are required at breeding sites. A common feature of most sites is a degree of habitat disturbance, which maintains bare substrate, and the openness of the vegetation.

Behaviour

Weak flyers, tend to dwell around habitat, but is beleived to use wind currents to disperse.

Status and distribution

This species is classed as nationally scarce in the British Red Data Book of Insects. Historically scarce, but in recent times has shown some range expansion. In Britain it is most numerous in southwest counties of England and Wales. It has been found in very small populations at scattered locations across Dorset.



Flight period

Main flight period is late May to September, peaking in June to mid August.

Similar species

The related, much commoner, Blue-tailed Damselfly superficially resembles this species but has a blue 'tail' on segment 8 only. At a glance could be confused with the two Red-eyed Damselfly species but are smaller, less robust looking insects and do not have red eyes.

More photographs

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Mature Male

Mature Female (photo © Brett Spencer)

Immature Male

Immature Female aurantiaca phase  

All photographs by kind permission & © of Ken Dolbear unless otherwise stated. All rights reserved.