Red-eyed Damselfly - Erythromma najas

Adult size

Overall length: 30 - 36mm   Hindwing length: 19 - 24mm

Distinguishing features

One of four species of damselflies which have an almost solid black abdomen and a blue ‘tail’ in males. Males have characteristic deep maroon-red eyes. Tend to be associated with floating vegetation. Could be confused with the much less common Small Red-eyed Damselfly.

Identification - for help with terms see glossary

Mature Males

Abdomen is all black with bright blue markings on segment 9 & 10. Eyes are deep maroon-red. The thorax from the side looks blue, but above looks bronze-black & unlike the Small Red-eyed Damselfly has no antehumeral stripes.

Immature males

Thorax is green as seen from side, and the tail markings are a dull brown colour as are the eyes at this stage.

Mature females

The abdomen has alternating thin green lines bisecting thick black segments. Has a bronze-black thorax as male but has incomplete green antehumeral stripes from above. From the side the thorax is green and the eyes are a reddish brown colour.

Immature females

Have not developed the blue ‘tail’ markings, and the sides of the thorax and antehumeral stripes are a pale green colour. Eyes are pale green.


Found in still water habitats mainly larger water bodies such as lakes, larger ponds gravel pits, canals and sluggish-flowing rivers with contain large expanses of floating vegetation.


Males will often be associated with floating leaves, favouring water lilies or pond weed where they will set up & defend territories, flying out to chase intruders.

Status and distribution

Has a southerly distribution restricted to central and southern Britain. Locally common in suitable habitat it has an irregular distribution in Dorset.

Flight period

Main flight period is mid May to September, peaking in June & July, before peak of Small Red-eyed damselfly.

Similar species

The similar, but smaller, Small Red-eyed Damselfly is sometimes found in the same habitat and careful observation is needed to distinguish the two species. Could be confused with the Blue-tailed Damselfly & Scarce Blue-tailed Damselfly, but these are smaller less robust looking insects and do not have red eyes.

More photographs

Click on the photos below to enlarge...


Mature Male 

Mature Female 

Immature Female

Mating Pair

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