British Insects: the Odonata
Black-tailed Skimmer Dragonfly.
Adults. Adults about 47–50–53 mm long. Average wingspan 77 mm; hindwings 35–40 mm long.
The eyes dorsally narrowly apposed to dorsally broadly contiguous; brown (in the female), or blue (in the male).
Legs black and brown (the femoral bases brown). Thoracic antehumeral stripes absent. The wings spread more or less horizontally in repose; dissimilar in shape and venation; sessile; unpatterned and clear. The inner wing venation blackish. Discoidal cell divided longitudinally into a conspicuous triangle and supra-triangle. Antenodal veins in the forewings 10–13 (fewer in the hindwings). Pterostigma well over twice but no more than five times as long as wide; black.
Abdomen lanceolate; 30–35 mm long; predominantly blue (in the male), or brown (in the female), or grey (sometimes, in old females); rather plain (in the male, but often with orange lateral markings, and darkened over the terminal segments), or predominantly longitudinally lined (the female with a dark medio-lateral band on either side along each segment); without mid-dorsal spots. The male abdomen without auricles on segment 2; with a single inferior anal appendage.
Nymphs. The nymphs stout, the body expanded in the middle; when mature, 23–25.5 mm long.
The postocular lobes curving sharply to the back of the head from some distance behind the eyes. The antennae 7 segmented. The mask having the prementum hollowed dorsally. The prementum bearing three (rarely two or four) long setae inserted near each lateral margin, and two medial fields of seven to eight short spiniform setae, the latter flanked by four setae of medium length. The body of the labial palps bearing (6–)7 major setae. Distal margins of the labial palps weakly crenate. Legs longer than the abdomen.
The abdomen terminating in five short spine-like appendages. The cerci no more than hald the length of the paraprocts. The abdomen with mid-dorsal spines. The mid-dorsal abdominal spines prominent on segments 3 to 6. The abdomen without a mid-dorsal spine on segment 8; gizzard with 4–8 folds.
Distribution. English Midlands, East Anglia, Wales, southeast England, southwest England, Isle of Wight, Ireland, and central southern England (absent from the English midlands except near the Welsh border). Adults on the wing early May to early September (generally in best mature condition late May to mid-July).
Classification. Anisoptera; family Libellulidae.
Illustrations. • Orthetrum cancellatum (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’.