Insects of Britain and Ireland: the families of Lepidoptera

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L. Watson and M. J. Dallwitz


Adults diurnal; small to medium sized; relatively short-bodied, or short-bodied to medium-bodied; medium built (wingspan more than 8 and less than 15 times the thoracic width); wings in repose apposed vertically over the back.

Head rough. Antennae very short to of medium length; extending to about 0.4–0.55 times the length of the forewing; inserted markedly less than one half the width of the head apart; clubbed. The club gradual (mostly), or gradual to abruptly terminal (elongate, straight or somewhat curved). Antennae of males simple; non-ciliate. Eyes conspicuously white-rimmed, notched or emarginate at the bases of the antennae and contiguous with the bases of the antennal sockets; hairy, or glabrous. Ocelli absent. Chaetosemata present. Maxillary palps absent. Labial palps ascending; 3 segmented. Proboscis fully developed; not scaly.

Wingspan (24–)28–48(–50) mm; 11–13 times the thoracic width. Forewings broad; 1.4–1.9 times as long as wide. The outer and hind margins angled at (86–)95–100(–110) degrees. The outer margin convexly curved to more or less straight; forewings apically blunt to pointed; forewings predominantly shining-metallic, or neither shining-metallic nor with shining metallic markings; ground colour predominantly dark brown (or fuscous), or coppery red, or blue, or purple; forewings without eye-spots above; forewings eye-spotted underneath near the tip, or not eye-spotted underneath near the tip. Hindwings broadly rounded, or trapezoidal; similar in breadth to the forewings; tailed, or not tailed; the upper surfaces conspicuously patterned above (often in females in the form of a subterminal row of small, sometimes faint orange marks bordered with black and/or white), or plain; with a discal spot (rarely), or with transverse lines, or with neither discal spot nor transverse lines (with the conventional lepidopterous lines and discal marks lacking or more or less obscured); silver-marked underneath (P. argus), or not silver-marked underneath (in the “Blues” usually multiply spotted with small dark spots and often with rows of dark dots embedded in orange spots along the termen); without a frenulum.

Neuration of forewings and hindwings dissimilar. Forewings 11 veined (usually, with vein 7 missing), or 10 veined (when veins 8 and 9 coincide); with 1 anal vein, or with 2 anal veins. The anal veins of the forewings representing 1b only, or comprising 1b and 1c. Forewings lacking a tubular vein 1c. Vein 1b of the forewings furcate proximally to simple. Forewings with a discal cell, or without a discal cell. Discal cell of the forewings without a tubular media (M) vein. Vein 7 missing, 8 and 9 stalked or coincident. Hindwings 9 veined; with 2 anal veins. The anal veins of the hindwings comprising 1a and 1b. Hindwings exhibiting vein 1a; lacking a tubular vein 1c; without a praecostal spur. The hindwing cell emitting more than six veins. 7 veins arising from the hindwing cell. The cell-derived hindwing veins 3+4 proximally joined (usually, connate only), or 3+4 proximally joined and 6+7 proximally joined. Vein 8 of the hindwings arising from the upper margin of the cell (from near its base); not approximating to vein 7.

Adults having all 6 legs fully developed and operational for walking. Fore-legs of female operational for walking. Fore-legs without a tibial epiphysis. Tibiae of middle legs 2-spurred. Posterior tibiae 2-spurred.

Tympanal organs absent.

Eggs, larvae and pupae. Eggs usually markedly flattened (mostly discoid, in Lycaena almost hemispherical); smooth or minutely pitted, or with projections. Larval prolegs 10. Larvae conspicuously, densely long-hairy to not densely long-hairy (often densely short-hairy, characteristically woodlouse-shaped, often intimately associated with ants in the later instars); exposed feeders (rarely), or concealed feeders. Mostly on legumes, but a few on Ericaceae, Labiatae, Cistaceae, Geraniaceae, Ilex, Hedera, Rhamnus, etc.

Pupae smooth and rounded (usually), or ridged and angular to smooth and rounded; conspicuously patterned, or plain; without shining-metallic spots; exposed, with no coccoon, or concealed; when ‘exposed’, not suspended, but attached at the tail and secured by a median girdle of silk; when ‘concealed’, subterranean, or on the surface of the ground.

British representation. Genera 19 (3 comprising adventives only); 26 species (including 8 adventive, 2 extinct). Aricia agestis (Brown Argus), Aricia artaxerxes (Durham Argus, Northern Brown Argus, Scotch Brown Argus, Castle Eden Argus), Callophrys rubi (Green Hairstreak), Celastrina argiolus (Holly Blue, Azure Blue), Cupido minimus (Little Blue), Cyaniris semiargus (Mazarine Blue - extinct, now occasionally adventive), Everes argiades (Short-tailed Blue - adventive?), Glaucopsyche alexis (Green-underside Blue, adventive), Lampides boeticus (Long-tailed Blue), Leptotes pirithous (Bloxworth Blue, Lang’s Short-tailed Blue, adventive), Lycaena alciphron (Purple-shot Copper, adventive), Lycaena dispar dispar (Large Copper - the extinct British subspecies), Lycaena hippothoë (Purple-edged Copper, adventive), Lycaena phlaeas (Small Copper), Lycaena tityrus (Sooty Copper, adventive), Lycaena virgaureae (Scarce Copper, former resident but extinct since about 1850), Lysandra bellargus (Adonis Blue), Lysandra coridon (Chalk-hill Blue), Maculinea arion eutyphron (Large Blue, the perhaps extinct British subspecies), Neozephyrus (Quercusia) quercus (Purple Hairstreak), Plebejus argus (Silver-studded Blue), Plebicula dorylas (Turquoise Blue, adventive), Polyommatus icarus (Common Blue), Plebicula dorylas, Satyrium (Strymonidia) pruni (Black Hair-streak), Satyrium (Strymonidia) w-album (White-letter Hairstreak), Syntaricus pirithous (adventive), Thecla betulae (Brown Hairstreak).

Classification. Butterflies. Suborder Ditrysia. Superfamily Papilionoidea.

Comments. Small, often brightly coloured butterflies; flight quick and agile but seldom sustained, hence often represented by localised colonies. With the exceptions of the ‘Hairstreaks', ‘Coppers’ and Cupido minimus, the life histories of British Lycaenidae involve symbiotic relationships with ants, which “milk” the larvae from their honey glands. The presence of ants around the larvae on their foodplants evidently serves to deter potential insect parasites and predators, and in some cases the relationship involves deliberate “farming” of the larvae by their protectors. In Britain, ants have been observed to carry larvae of Lysandra coridon and Plebajus argus in their jaws and deposit them on the approriate foodplants conveniently near their nests; and in the famous case of the Large Blue (Maculinea arion), the butterfly larvae are virtually parasitic, being taken into the ants’ nest and fed to maturity on their own larvae. For detailed discussion, see Ford (1945).

Illustrations. • Lycaenidae (1), Hairstreaks and Coppers: Newman. • Lycaenidae (2), Blues: Newman. • Lycaenidae (3), Blues cont.: Newman. • Maculinea arion ssp. eutyphron (Large Blue - endemic British subspecies: photos). • Lampetes boeticus (Long-tailed Blue: photos. • Celastrina argiolus subsp. britanna (Holly Blue: photos). • Celastrina argiolus (Holly Blue: Giles Watson, photos). • Lysandra coridon (Chalk Hill Blue) and L. bellargus Adonis or Clifen Blue): photos. • Polyomatus icarus (Common Blue): photos. • Everes argiades, Glaucopsyche alexis (Bloxworth or Short-tailed Blue, Green-underside Blue: Kirby). • Lycaena dispar dispar (Large Copper: B. Ent. 12). • Lycaena dispar: B. Ent. 12, legend+text. • Lycaena dispar: B. Ent. 12, text cont.. • Lycaena phlaeas (Small Copper) and L. virgaureae (Scarce Copper): photos. • Lycaena phlaeas (Small Copper: Hübner/Curtis). • Satyrium pruni (Black Hair-streak: B. Ent. 264). • Satyrium pruni (B. Ent. 264, legend+text). • Satyrium pruni (B. Ent. 264, text cont.). • Callophrys rubi (Green Hairstreak: Hübner/Curtis). • Callophrys, Satyrium (Strymonidia), Thecla, Neozephyrus (Quercusia) (Hairstreaks: Coleman). • Polyommatus icarus (Common Blue: Hübner/Curtis). • Lycaena, Celastrina, Cupido, Cyaniris, Lampedes (Purple-edged Copper, Blues: Coleman). • Aricia, Lysandra, Maculinea, Plebejus, Polyommatus (Blues: Coleman). • Plebicula dorylas, Leptotes pirithous: Kirby. • Lycaena virgaureae (Scarce Copper: Kirby). • Lycaena alcifron, L. tityrus: Kirby.

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. Insects of Britain and Ireland: the families of Lepidoptera. Version: 8th June 2016.’.