Friday, 2 September 2011

Small Red-eyed Damselflies in Gloucestershire

September 1, 2011:
A large pool near Tewkesbury known for its rich dragonfly fauna also has the fairly scarce Small Red Damselfly (Erythromma viridulum). With hot sunny weather forecast for the day, a visit was made especially to see this species.

Small Red-eyes are relatively tiny damselflies but are superficially similar to the closely-related and much more widespread Red-eyed Damselfly (E. najas). They are however smaller and more delicate and have a narrower, waisted abdomen which is noticeably swollen near the apex. Perhaps the best identification character though is the colour of the second and eighth segments which is mostly blue (but largely black in the larger species).

[Small Red-eyed Damselfly (E. viridulum) the with blue coloration clearly visible on segments 2 and 8]

[An enlarged view showing segments 2 and 8 to be mainly blue]

[For comparison, a Red-eyed Damselfly (E. najas) showing segments 2 and 8 to be mainly black]

The males spent all the time out on the open water where they perched on floating vegetation and lily-pads and were not easy to view closely or to photograph. They need warm sunny weather to be active and today this ceased immediately the sun went in. Small Red-eyes are quickly spreading northwards and have already reached as far as the Midlands.

Some tandem pairs were also seen ovipositing on the floating sphagnum, as below.

[The larger Red-eyed Damselfly (E. najas) was also present with its comparatively broader, non-waisted abdomen]

Also seen at the pool were Common and Ruddy Darters, Southern, Brown, and Migrant Hawkers, one Red-eyed Damselfly, many Common Blue and Blue-tailed Damselflies and a few Banded Demoiselles. A Kingfisher also put in appearances on several occasions.

[Ruddy Darter]

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