Insects of Britain and Ireland: butterflies

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L. Watson and M. J. Dallwitz


Adults. Wingspan 25–38 mm; the fringes white, not banded. Medium built; short-bodied to medium-bodied. The eyes white-rimmed; notched or emarginate at the bases of the antennae and contiguous with the bases of the antennal sockets. Antennae reaching noticeably less than halfway to the wingtips to reaching about halfway to the wingtips. The antennal clubs gradual-elongate; not curved. Labial palps ascending. Having all 6 legs fully developed and operational for walking. Fore-legs without a tibial epiphysis. Tibiae of middle legs 2-spurred. Posterior tibiae 2-spurred.

Forewings. Forewings apically blunt to pointed. The outer margins convexly curved to more or less straight. Uppersides of the forewings blue (male), or dark brown, or fuscous (female); with a conspicuous discal mark; light, bright blue with a narrow black border in the male, brown in the female.

Hindwings. Hindwings broadly rounded; not tailed; with the outer margins not scalloped. Uppersides of the hindwings blue (male), or fuscous (female); plain; without a discal mark; light, bright blue with a narrow black border in the male, brown with faint orange spots around the termen in the female.

Undersides of wings. Undersides of the wings multiply patterned with pale-ringed black spots.

Undersides of the forewings reddish grey, with a subterminal row of white-ringed black spots, a white-edged, 8-shaped black discal mark, and margined along the termen with contiguous spots that are orange internally and white externally; conspicuously dark-veined to not dark-veined.

Undersides of the hindwings marked and coloured similary to those of the forewings, but with a heart-shaped white mark in the middle; with a subterminal row of orange spots which are apposed to terminal black dots; with orange markings (sub-terminally).

Wing venation. Forewings 11 veined. Forewings with 1 tubular anal vein; the anal veins of the forewings representing 1b only; vein 1b simple. Forewings with a discal cell to without a discal cell (the transverse vein very faint); vein 2 departing from the hind margin of the cell in its distal quarter to departing from the cell less than three-quarters of the distance from its base (from at least 2/3 out). Forewing vein 5 conspicuous from the base and traversing the faint transverse vein, 6 separate, 7 and 8 long-stalked with 8 very short to the costa, 9–11 separate from the cell.

Hindwings 9 veined; without a praecostal spur; with 2 anal veins; exhibiting vein 1a; the anal veins comprising 1a and 1b. Hindwings with a closed discal cell to without a closed discal cell; the transverse vein vestigial only to lacking. The cell-derived hindwing veins 3+4 proximally joined (connate). Hindwing veins 2, 3 and 4 from one stalk, 5 separate and absent or vestigial proximal to the faint transverse vein, 8 separate and sharply curved along the costa.

Eggs, larvae, pupae. The larvae woodlouse-shaped. On Melilotus officinalis.

Pupae smooth and rounded; plain.

British representation. 1 species. Plebicula dorylas (Turquoise Blue). The adults abroad May to August.

Status in Britain. Rare ocurrence representing occasional, genuine immigrants (on the evidence of dubious 18th and 19th Century records), or adventive.

Distribution. Migrants from mainland Europe perhaps occasionally reaching southeast England, or central southern England, or southwest England, or Isle of Wight. Frequenting open places.

Classification. Superfamily Papilionoidea. Lycaenidae.

Illustrations. • Plebicula dorylas, Leptotes pirithous: Kirby, 1907.

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Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 2008 onwards. Insects of Britain and Ireland: butterflies. Version: 16th May 2016.’.