Irish Damselfly (aka Crescent Bluet)

Fast Facts

Latin name: Coenagrion lunulatum

Notable feature: Similar to other blue damselflies, however both the female and male Irish Damselfly are darker and shorter-bodied when compared to other blue damselflies.

Conservation Status: Least Concern

Where in the UK: Northern Ireland

Irish Damselfly (Coenagrion lunulatum) © Michael Bell


The adult Irish Damselfly is a small, slender insect; males and females differ in appearance.  The male Irish Damselfly is blue and black above, with distinctive markings on its second abdominal segment; the underside of the head and thorax is also bright green on mature males.  The female Irish Damselfly is mainly black with blue and green markings also, but much less distinctive than the males.

    • Size:  Up to 30mm in length.
    • Life span:  Annual life cycle; but adults live a matter of weeks.
    • Diet:  The Irish Damselfly feeds on small invertebrates and insects.
    • Reproduction: Female Irish Damselflies lay eggs into the submerged stems of aquatic plants (particularly pondweeds).  These eggs hatch within a few weeks and the larvae grow through a series of moults until they are fully grown in spring of the following year.
    • When to see:  From May to the end of July
    • Population Trend:  Northern Ireland holds the entire UK population and a significant proportion of the Irish population (around 40%). There is evidence of decline, estimated at about 10% per decade.
    • Threats: Climate change and severe weather – habitat shifting and alteration.  Pollution, including agricultural and forestry practices.
    • Fun Fact:  One of the English names (Irish Damselfly) comes from the fact that it is found in Ireland but not in Britain.

How you can help: 

As yet, Northern Ireland’s invertebrate fauna is relatively unknown, particularly when compared with many other areas; this is demonstrated by the relatively recent discovery of this damselfly in 1981.

Whilst Buglife is working to increase awareness of Northern Ireland’s invertebrates through various projects we need your help.  To find out more about our work in Northern Ireland visit our Buglife Northern Ireland webpage

Join a recording scheme and log your finds – download the iRecord app and get recording!

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