Insects of Britain and Ireland: butterflies
Adults. Wingspan 30–40 mm (L. bellargus), or 33–40 mm (L. coridon); the fringes conspicuously light-and-dark banded. Medium built; short-bodied. The eyes white-rimmed; notched or emarginate at the bases of the antennae and contiguous with the bases of the antennal sockets; hairy. Antennae white-ringed, reaching noticeably less than halfway to the wingtips to reaching about halfway to the wingtips; inserted markedly less than one half the width of the head apart. The antennal clubs gradual-elongate (tapered); not curved; not flattened. 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 and hind margins angled at about 96–100 degrees. The outer margins convexly curved to more or less straight. Uppersides of the forewings pale shining (L. coridon) or bright lilac (L. bellargus) blue (in the males), or dark brown, or fuscous (basally sprinkled blue, in the females); contrastingly dark-veined (in L. coridon), or not conspicuously dark-veined (in L. bellargus); with a conspicuous discal mark (usually, in the females), or without a discal mark; blue with a dark fuscus terminal fascia or a black terminal edge ( in males of L. coridon and L. bellargus, respectively; dark brown and plain or with a terminal series of tiny pale rings, in female L. coridon; plain or with a subterminal series of orange spots (or hints of these) in female L. bellargus.
Hindwings. Hindwings broadly rounded, or trapezoidal; with the outer margins not scalloped. Uppersides of the hindwings pale shining (L. coridon) or bright lilac (L. bellargus) blue (in the males), or dark brown, or fuscous (basally sprinkled blue, in the females); conspicuously dark-veined (in L. coridon), or not dark-veined (in L. bellargus); conspicuously patterned (in the females, and in males of L. coridon), or plain (in males of L. bellargus); with a conspicuous discal mark (sometimes in female L. coridon, represented by a light spot), or without a discal mark; of both sexes in L. coridon and females of L. bellargus usually with a terminal series of black spots, these pale-ringed (male L. coridon) or orange-ringed; otherwise plain apart from the thin black border in male L. bellargus.
Undersides of wings. Undersides of the wings multiply patterned with pale-ringed black spots.
Undersides of the forewings whitish to brown, usually with about 4–7 black, white-ringed spots in an irregular posterior row, 3–5 in the disc, and a subterminal series of blackish spots or dots sometimes encircled with white and/or orange; with two black spots before the middle.
Undersides of the hindwings whitish to brown, with numerous black, white-ringed spots in the middle, and a series of black, anteriorly orange spots subterminally; i.e., colour-patterned like the forewings, but the discal spots are smaller; usually with a subterminal row of orange spots which are apposed to terminal black dots; usually with a conspicuous discal mark (in the form of a pale spot); with orange markings.
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. Eggs discoid; densely spinulose. The larvae woodlouse-shaped; associated with ants in the later instars; exposed feeders. On Lotus, Anthyllis, Hippocrepis, etc.
Pupae smooth and rounded; more or less concealed (unattached, in litter or more or less subterranean).
British representation. 2 species. Lysandra bellargus (Adonis Blue), Lysandra coridon (Chalk-hill Blue). The adults abroad May to September.
Status in Britain. Indigenous.
Distribution. Northern England, English Midlands, East Anglia, Wales, southeast England, central southern England, southwest England, and Isle of Wight. Frequenting open places. Habitats mostly calcareous (L. coridon), or calcareous and non-calcareous (L. bellargus).
Classification. Superfamily Papilionoidea. Lycaenidae.
Illustrations. • Lysandra coridon (Chalk Hill Blue) and L. bellargus Adonis or Clifden Blue): photos. • Lysandra coridon (Chalk Hill Blue: Giles Watson, photos). • Lysandra coridon (Chalk Hill Blue): egg, larva, pupa. • Lysandra bellargus (Adonis Blue): egg, larva, pupa.
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. 2008 onwards. Insects of Britain and Ireland: butterflies. Version: 16th May 2016. delta-intkey.com’.