Red-eyed Damselfly - Erythromma najas
Adult sizeOverall length: 30 - 36mm Hindwing length: 19 - 24mm
Distinguishing featuresOne 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
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.
Thorax is green as seen from side, and the tail markings are a dull brown colour as are the eyes at this stage.
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.
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.
HabitatFound 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.
BehaviourMales 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 distributionHas a southerly distribution restricted to central and southern Britain. Locally common in suitable habitat it has an irregular distribution in Dorset.
Flight periodMain flight period is mid May to September, peaking in June & July, before peak of Small Red-eyed damselfly.
Similar speciesThe 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 photographsClick on the photos below to enlarge...
All photographs by kind permission & © of Ken Dolbear unless otherwise stated. All rights reserved.