British Insects: the Odonata
Large Red Damselfly.
Adults. Adults about 33–36–39 mm long (the sexes similar in length). Average wingspan 44 mm (male), or 48 mm (female); hindwings 19–24 mm long.
The eyes lateral and widely separated; red.
Legs black and yellow (with yellow coxae). Legs not red. Thoracic antehumeral stripes present (conspicuous, double); yellow (in a variety of the female), or orange to red (usually). The wings held vertically 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, without transverse veinlets). The wings exhibiting 3 postquadrilateral cells between the quadrilateral cell and the subnodus (in the hindwings), or 3–4 postquadrilateral cells between the quadrilateral cell and the subnodus (in the forewings). Antenodal veins in the forewings 2. Pterostigma pale with a dark centre (brown, black-centred). The hindwings with only one row of cells distal to the pterostigma between the costa and the radial vein.
Abdomen linear from base to tip; 25–29 mm long; predominantly red (usually, in both sexes, with black or black and yellow markings), or black (with yellow markings, in f. melanotum); predominantly transversely banded, or predominantly longitudinally lined (typically with segments 7, 8 and 9 mostly black and the other segments with narrow black or black and yellow bands posteriorly in both sexes, and the female with a narrow median black line; but in f. melanotum, all the segments are mainly black with narrow yellow bands between); without mid-dorsal spots. The male abdomen without auricles on segment 2; with paired inferior anal appendages. Abdominal segment 8 of the female without a ventral apical spine.
Nymphs. The nymphs elongate and slender-bodied, gradually tapering posteriorly; when mature, 19–22.5 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; with the first flagellar segment longer than the pedicel. The mask narrowed gradually to the hinge; without a median cleft. The prementum bearing 6–8 major setae (3+3 to 4+4). The body of the labial palps bearing 6–7 major setae. The outer margins of the labial palps without spines. Distal margins of the labial palps irregularly and quite coarsely toothed (with one large tooth). The moveable hooks of the labial palps without setae. The apical combs of the tibiae mainly of trifurcated setae.
The abdomen terminating in three conspicuous caudal gills. The three caudal appendages all lamellar. The caudal lamellae broadly oblanceolate; apiculate- pointed; patterned beyond the middle with conspicuous a dark cross; hairy on both margins to beyond the middle; without nodes, and with no clear demarcation between proximal and distal series of marginal hairs; with much-branched primary tracheal branches leaving the main trunk at an upward angle. The gizzard with 8–16 radially symmetrical folds.
Distribution. Northern Scotland, southern Scotland, northern England, English Midlands, East Anglia, Wales, southeast England, southwest England, Isle of Wight, Ireland, and central southern England (very widespread and generally common). Adults on the wing late April to late September (generally in best mature condition mid-May to early August).
Classification. Zygoptera; family Coenagriidae.
Illustrations. • Pyrrhosoma nymphula (from Lucas). • Pyrrhosoma nymphula: photo, Giles Watson. • Pyrrhosoma nymphula: nymph (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’.