Insects of Britain and Ireland: butterflies

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L. Watson and M. J. Dallwitz


Adults. Wingspan 25–31 mm; the fringes conspicuously light-and-dark banded. Medium built; medium-bodied. The eyes white-rimmed; notched or emarginate at the bases of the antennae and contiguous with the bases of the antennal sockets; glabrous. Antennae white-ringed, reaching noticeably over halfway to the wingtip. The antennal clubs somewhat gradual-elongate to abrupt (blunt); 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 100–105 degrees. The outer margins convexly curved to more or less straight. Uppersides of the forewings dark iridescent fuscous, or dark brown; usually with a conspicuous discal mark (this either black, then sometimes white-ringed, or white); with a sometimes more or less obsolete terminal series of orange spots.

Hindwings. Hindwings broadly rounded. Uppersides of the hindwings dark iridescent fuscous, or dark brown; conspicuously patterned, or plain; without a discal mark; colour-patterned like the forewings, but the orange spots often more in evidence and brighter.

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

Undersides of the forewings pale brown, complexly patterned with a discal mark and a subterminal row of white, usually black-centred spots, and a terminal row of orange spots of variable intensity that are outer-edged first black then white; with no black spots before the middle.

Undersides of the hindwings pale brown, with the discal mark, three anterior spots and a postmedian series being either black and broadly white-ringed or entirely white, and a subterminal series of orange spots that are outer-edged first black and then white; usually with a subterminal row of orange spots which are apposed to terminal black dots; with a conspicuous discal mark.

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 rather faint and absent proximally to 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; the transverse vein complete to vestigial only (vestigial between 4 and 5, weak between 5 and 6). The cell-derived hindwing veins 3+4 proximally joined (connate), or 3+4 proximally joined and 6+7 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; hairy. On Helianthemum and Erodium.

Pupae smooth and rounded; conspicuously patterned; exposed, with no coccoon to concealed (“sometimes unattached”, “held in position by a few silken threads between leaves of the food plant”).

British representation. 2 species. Aricia agestis (Brown Argus), Aricia artaxerxes (incorporating more or less different forms referred to as Durham Argus, Northern Brown Argus, Scotch Brown Argus, and Castle Eden Argus). The adults abroad May, June, and August.

Status in Britain. Indigenous.

Distribution. Northern Scotland, southern Scotland, northern England, English Midlands, East Anglia, Wales, southeast England, central southern England, southwest England, and Isle of Wight. Frequenting open places. Habitats calcareous and non-calcareous.

Classification. Superfamily Papilionoidea. Lycaenidae. Aricia is represented in Britain by a polymorphic complex of ecotypes, variously treated by different authorities as one species (agestis) or two (agestis and artaxerxes, with the latter incorporating subspecies artaxerxes and salmacis. The taxonomic interpretation is clearly unsatisfactory, and is the subject of ongoing work.

Illustrations. • Aricia agestis/artaxerxes (Brown Argus/Northern Brown Argus): photos. • Aricia agestis/artaxerxes (Brown Argus/Northern Brown Argus): egg, larva, pupa. • Lycaenidae (3), Blues cont.: Newman, 1871. • Aricia, Lysandra, Maculinea, Plebejus, Polyommatus (Blues: Coleman, 1860).

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.’.