British Insects: the Odonata

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L. Watson and M. J. Dallwitz

Coenagrion puella (Linnaeus, 1758)

Agrion puella.

Azure Damselfly.

Adults. Adults about 30–33–36 mm long. Average wingspan 41 mm; hindwings 16–23 mm long.

The eyes lateral and widely separated; brown and green (female), or brown and blue (male). The front of the head immediately interior to the eyes not pale whitish blue (mostly black).

The prothorax posteriorly more or less entire. Legs black and blue ((-ish) below). Legs not red. Hind tibia without a featherlike expansion. Thoracic antehumeral stripes present (the humeral stripes also conspicuous); blue (in the male), or greyish (in the female). 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. Antenodal veins in the forewings 2. Pterostigma more or less isodiametric; pale with a dark centre (black centred and pale ringed). 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 (very slender); 23–30 mm long; predominantly mainly black (in some females), or blue and black (in males and some females); predominantly transversely banded (in the male, segments 1 and 2 are complexly patterned dorsally with black, while segments 3 to 6 and 9 are posteriorly black-banded, segments 7 and 10 are entirely black, and segment 8 is entirely blue; while in the typical female, segments 1 and 2 are dorsally black-patterned, segments 3 to 9 are black, segment 10 is blue, and the narrow intersegmental bands are greyish or yellowish apart from the last two, which are blue. In addition, there are blue forms of the female that are more or less intermediate in pattern between the typical male and the typical female forms); without mid-dorsal spots. Abdominal segment 2 of the male blue, with a black U-shaped dorsal mark which is separated from the black circlet behind it (usually), or blue, with a black U-shaped dorsal mark which is joined to the black circlet behind it (rarely). 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, 22–25.75 mm long.

The head with prominent spots; in dorsal view markedly narrowing from immediately behind the eyes. The postocular lobes curving sharply to the back of the head from some distance behind the eyes. The antennae 7 segmented; 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 (8–)10 major setae (usually 5+5). The body of the labial palps bearing (5–)6(–7) major setae. The outer margins of the labial palps without spines. 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 pointed (shortly apiculate); hyaline without coloured markings; hairy on both margins to beyond the middle; nodate, with the marginal hairs coarser proximally to the node and finer beyond it; with much-branched primary tracheal branches leaving the main trunk at an upward angle. The gizzard with 8–16 radially symmetrical folds.

Distribution. Southern Scotland, northern England, English Midlands, East Anglia, Wales, southeast England, southwest England, Isle of Wight, and Ireland (widespread and generally common, but very local in Scotland). Adults on the wing late April to early September (generally in best mature condition late May to mid-August).

Classification. Zygoptera; family Coenagriidae.

General comments. The males and the blue form of the female are usually distinguishable from C. pulchellum by the dorsal black U-shaped mark on segment 2 usually (but not always) being free from the black band posterior to it.

Illustrations. • Coenagrion puella (from Lucas). • Coenagrion puella: male and female paired prior to egg-laying (photo, Giles Watson). • Coenagrion puella: habitat and communal egg-laying (photo, Giles Watson). • Coenagrion puella: detail of 3 egg-laying pairs (photo, Giles Watson). • Coenagrion puella: male and female paired after egg-laying (photo, Giles Watson). • Coenagrion puella, male: photo, Giles Watson. • Coenagrion puella: 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’.

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