The Small Red-eyed Damselfly – Erythromma viridulum, is a more recent visitor to the region, but now well established. One of two very similar red-eyed damselfly species, positive identification needs care.
|Coenagrionidae||Blue or red Damselflies|
The male’s distinctive red eyes, and dark abdomen with its prominent blue ‘tail-light’, make it easy to separate from all other damselflies except the Red-eyed Damselfly – Erythromma najas, which is noticeably larger – the Small Red-eyed Damselfly is the region’s smallest.
In the male, segments 9 and 10 are entirely blue, forming the prominent ‘tail-light’. The blue colouring extends to the sides of segment 8, in a wedge shape. Segments 2 and 3 also have blue sides, with black on the dorsal surface. Seen from above, males feature a black ‘X’ marking on segment 10. Overall, there are more blue areas on the Small Red-eyed that in the Large Red-eyed.
The female has a black abdomen without a tail-light and has duller yellow greenish eyes. There is a thin yellow shoulder stripe on the sides of the thorax.
The most similar species is the Red-eyed Damselfly – Erythromma najas, and the differences are summarised below:
|Feature||Red-Eyed Damselfly – |
|Small Red-Eyed Damselfly – |
|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.
Like the similar Red-eyed Damselfly – Erythromma najas, 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.
A more recent addition to Bedfordshire’s checklist, the Small Red-eyed damselfly is extending its range within the county’s borders (and indeed the rest of the UK). First discovered at the Finger Lakes at Priory CP, it has since dispersed and has been reported at many other sites including Felmersham NR, Wrest Park, Willington, and Sundon Chalk Quarry.
Visible between early July and early September, peaking in August. This is later than the Red-eyed Damselfly – Erythromma najas, which can be a useful aid in separating the two Red-eyed species.