Bedfordshire Odonata - Red-Eyed Damselfly

Red-eyed Damselfly – Erythromma najas

European common name: Large Redeye

BDS pronunciation: erry-thromm-ah nye-ass

The Red-eyed Damselfly – Erythromma najas, is a common sight in the region. One of two very similar red-eyed damselfly species, positive identification needs care.

Classification:

Odonata
	Zygoptera		Damselflies
		Coenagrionidae	Blue or red Damselflies

The male’s distinctive red eyes, dark abdomen with its prominent blue ‘tail-light’ on segments 9 and 10, make it easy to separate from all other damselflies except the Small Red-eyed Damselfly – Erythromma viridulum. The upper surface of the thorax is black and there is no shoulder stripe.

The female is green and black without a tail-light and has duller brownish red eyes. Shoulder stripe is narrow and incomplete.

Stronger flier, with proportionately larger wings than other blue damselflies.

The most similar species is the Small Red-eyed Damselfly – Erythromma viridulum, and the differences are summarised below:

Feature	Red-Eyed Damselfly – Erythromma najas	Small Red-Eyed Damselfly – Erythromma viridulum
Abdomen	Features a grey pruinescence	Glossy black, no pruinescence
Segments	1, 9 & 10 blue, the rest are black	2, 3 & 8 also (mostly) blue. 10 features a black ‘X’ marking seen from above
Wings	Wings extend to S8	Wings extend to S7
Legs	All black	Black with subtle blue stripe
Eyes	Blood red	Paler red, tomato-like
Flight period	May – September	July – September

For other blue damselflies in the region, the obvious distinction is the red eyes of the male, and the generally dark abdomen in both the male and the female. Other things to look out for are noted below.

White-legged Damselfly – Platycnemis pennipes
Larger, much paler colouring, white legs, black is much less extensive on dorsal segments, and four shoulder stripes.
Azure Damselfly – Coenagrion puella
Obvious ‘U’ shaped marking on segment 2 and blue eyes in the male. Blue (or green in some females) colouring on abdomen more extensive. Narrow shoulder stripe on the male, and unbroken shoulder stripe in the female.
Common Blue Damselfly – Enallagma cyathigerum
‘Mushroom’ or ‘lollipop’ shaped marking on segment 2 of the male and blue eyes rather than red (male). Blue (or green in some females) colouring on abdomen much more extensive. Broad shoulder stripe.
Blue-tailed Damselfly – Ischnura elegans
Tail-light doesn't extend to the tip; only segment 8 coloured blue (other colours in some female colour forms). Narrow shoulder stripes, which may be absent in some female colour forms.

Similar to the Small Red-eyed Damselfly – Erythromma viridulum, and favours still waters, large ponds, lakes, gravel pits and slow rivers, especially where there is floating vegetation – they are often seen on water lilies or floating mats of algae.

Common throughout the county, particularly along the River Great Ouse. They are abundant at Felmersham NR.

Visible from May to September, peaking in June.