British Insects: the Odonata
Calopteryx virgo Linnaeus.
Adults. Adults about 41–45–49 mm long. Average wingspan 58 mm (male), or 63 mm (female); hindwings 29–36 mm long.
The eyes lateral and widely separated; brown to red (reddish).
Thoracic antehumeral stripes absent. The wings held vertically in repose; similar in shape and venation; sessile; colour tinted throughout (in the female), or with a broad, purple-brown to deep blue-violet fascia extending from costa to hind margin, and occupying all but their bases and tips (in the male). The tinting in the female, dull purplish brown. The inner wing venation blackish (finer than in A. splendens). Discoidal cell a simple quadrilateral, not longitudinally divided (elongated-rectangular, with numerous transverse veinlets). Antenodal veins in the forewings about 25–30 (numerous, as also in the hindwings). Pterostigma (false) present (in the female), or absent (in the male); elongated but only about about twice as long as wide (in the hindwings), or well over twice but no more than five times as long as wide (and larger, in the forewings); of females, white.
Abdomen linear from base to tip (very slender); 33–38 mm long; predominantly blue, or blue to green (blue and sometimes greenish towards the extremity in males), or green and bronze (green and posteriorly coppery-tinged in females); metallic; plain. 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, 39–45 mm long.
The postocular lobes curving smoothly to the back of the head from immediately behind the eyes. The antennae with the scape as long as the other segments taken together. The mask abruptly narrowed well before the hinge, with the prementum stalked; with a wide median cleft extending half the length of the prementum. The cleft more than four time as long as its maximum width (i.e., wider than in A. splendens). Distal margins of the labial palps coarsely toothed (with three large, curved teeth). The apical combs of the tibiae of spinate setae.
The abdomen terminating in three conspicuous caudal gills. The three caudal appendages comprising a lamellar median and three-edged laterals. The caudal lamellae without nodes, and with no clear demarcation between proximal and distal series of marginal hairs. The gizzard with 8–16 radially symmetrical folds.
Distribution. Northern Scotland, northern England, English Midlands, East Anglia, Wales, southeast England, southwest England, Isle of Wight, Ireland, and central southern England (a generally western distribution, being scarcer eastwards and northwoards). Adults on the wing late April to early September (generally in best mature condition late May to early August).
Classification. Zygoptera; family Agriidae.
Illustrations. • Agrion virgo (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’.