Insects of Britain and Ireland: butterflies
Adults. Wingspan (32–)38–48 mm (dwarfism being not uncommon); the fringes conspicuously light-and-dark banded to 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; hairy. Antennae reaching noticeably less than halfway to the wingtips to reaching about halfway to the wingtips. The antennal clubs gradual-elongate (the antennae white-ringed); curved to not curved; 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 pointed, or blunt to pointed. The outer and hind margins angled at about 100–105 degrees. The outer margins slightly convexly curved to more or less straight. Uppersides of the forewings lilac blue (sprinkled with black); with a conspicuous discal mark; usually more or less conspicuously exhibiting a small crescentic black discal mark and a curved postmedian series of 3–6 black spots, but the spots can be almost obsolete; the costa and termen suffused dark fuscous.
Hindwings. Hindwings broadly rounded; with the outer margins scalloped to with the outer margins not scalloped. Uppersides of the hindwings lilac blue (sprinkled with black); conspicuously patterned; without a discal mark; with a dark fuscous terminal band, otherwise plain or sometimes with 2 or 3 black dots posteriorly.
Undersides of wings. Undersides of the wings multiply patterned with pale-ringed black spots.
Undersides of the forewings pale ochreous grey, with the discal mark and a postmedian series of about 7 spots all large, black and pale-ringed, and a double series of smaller black-and-white spots along the termen.
Undersides of the hindwings ochreous grey, with basal spots which are additional to the forewing pattern, the discal mark, a postmedian series of spots (smaller than those of the corresponding forewing series) and a double series of small terminal spots all black and pale-ringed; with neither orange spots nor an orange band; without a discal mark; without orange markings.
Wing venation. Forewings 11 veined; without basally dilated veins. 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 inconspicuous or incomplete between veins 4 and 5); vein 2 departing from the cell less than three-quarters of the distance from its base (from about 2/3 out). Forewing veins 6 separate, 7 reduced (missing according to Meyrick), 9 out of 8 and very short, 10 and 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. The transverse vein lacking. Hindwing veins 2, 3 and 4 from one stalk, 5 separate, 6 and 7 also stalked, 8 separate and sharply curved along the costa.
Eggs, larvae, pupae. Eggs discoid; finely, densely spinulose. The larvae woodlouse-shaped; associated with ants in the later instars (being collected and conveyed to their nests by ants of more than one species, and fed to maturity on ant larvae); exposed feeders (when young), or concealed feeders (subsequently). First feeding on flowers of Thymus and at this stage cannibalistic, subsequently collected by ants and conveyed to their nests, where they feed to maturity on ant larvae.
Pupae smooth and rounded; without shining-metallic markings; concealed (subterranean, within ants nests).
British representation. 1 species. Maculinea arion eutyphron (Large Blue). The adults abroad June and July.
Status in Britain. Formerly indigenous but now extinct. TheLarge Blue was described by Newman in 1871 as "decidedly local", but he recorded it from ten counties, ranging from South Devon north to Northamtonshire. By 1927, Meyrick regarded it as scarce and nearly extinct except in the SW. Bradley's authoritative Check List (2000) represents the indigenous British subspecies as .... extinct, ..... last seen SW England in the 1970s. Maculinea arion is now pathetically represented in Britain (cf. the Large Copper) by a population of the mainland-European subspecies, M. arion arion, introduced from Sweden in the 1980s and currently conserved somewhere in SW England.
Distribution. Southwest England. Frequenting open places. Habitats calcareous.
Classification. Superfamily Papilionoidea. Lycaenidae.
Illustrations. • Maculinea arion ssp. eutyphron (Large Blue - endemic British subspecies: photos). • Maculinea arion (Large Blue): egg and pupa. • Maculinea arion (Large Blue) larva carried by ant (Frohawk).
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’.