British Insects: the Odonata
Scarce Emerald Damselfly.
Adults. Adults about 35–42 mm long (the males somewhat the longer). Average wingspan 45 mm (male), or 47 mm (female); hindwings 20–25 mm long.
The eyes lateral and widely separated; green (in the female), or blue (in the male).
Legs black and yellow (black with yellowish lines on the femora). Thoracic antehumeral stripes absent. The wings held partly open in repose; similar in shape and venation; petiolate; unpatterned and clear. The inner wing venation blackish. Discoidal cell a simple quadrilateral, not longitudinally divided (trapezoid, not crossed by veinlets). Antenodal veins in the forewings 2. Pterostigma present (in both sexes); elongated but only about about twice as long as wide (or little more); black to dark brown.
Abdomen linear from base to tip to linear from a conspicuously swollen base, or swollen both basally and distally and markedly constricted in between (the basal swelling and sliight median constriction more apparent in the male); 26–30 mm long (female), or 28–33 mm long (male); predominantly green (marked with blue basally and apically in the male); metallic; almost plain (in the female), or predominantly transversely banded (the male with blue banding on segments 1, 2, 9 and 10, and both sexes with very narrow yellow bands between the segments); without mid-dorsal spots. The male abdomen without auricles on segment 2; with paired inferior anal appendages.
Nymphs. The nymphs elongate and slender-bodied, gradually tapering posteriorly; when mature, 29–32 mm long.
The postocular lobes curving sharply to the back of the head from some distance behind the eyes. The antennae with the scape considerably shorter than the other segments taken together. Distal margins of the labial palps irregularly and very coarsely toothed. The moveable hooks of the labial palps with three or more setae. The apical combs of the tibiae mainly of bifurcated setae.
The abdomen terminating in three conspicuous caudal gills. The three caudal appendages all lamellar. The caudal lamellae lanceolate (more obviously tapered towards the apex than in L. sponsa); blunt; without nodes, and with no clear demarcation between proximal and distal series of marginal hairs; with the primary tracheal branches departing more or less at right angles to the main trunk, themselves branching only near the margin. The gizzard with 8–16 radially symmetrical folds.
Distribution. Northern England, English Midlands, East Anglia, and southeast England (probably now confined to East Anglia and adjoining southeastern England). Adults on the wing early June to early September (generally in best mature condition late June to mid-August).
Classification. Zygoptera; family Lestidae.
General comments. The adults more robustly built than in Lestes sponsa, and the nymph differs from that of the latter in that the moveable hook of the labial palp bears three or more spines.
Illustrations. • Lestes dryas (from Lucas).
To view the illustrations with detailed captions, go to the interactive key. This also offers full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, and distributions of character states within any set of taxa.
Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2003 onwards. British insects: Dragonglies and Damselflies (Odonata). Version: 1st January 2012. http://delta-intkey.com’.