Insects of Britain and Ireland: butterflies

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L. Watson and M. J. Dallwitz


Adults. Wingspan 44–60 mm (hyale), or 47–67 mm (croceus); the fringes not banded. Very slender-bodied to medium built; short-bodied. The eyes glabrous. The head and antennae rosy-tinged. Antennae reaching noticeably less than halfway to the wingtips. The antennal clubs rather abrupt, or gradual-elongate; not curved; not flattened (blunt). Labial palps ascending (appressed to the frons). 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. 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 white, or yellow, or primrose; with a conspicuous discal mark (this in the form of a black spot); blackish-bordered at the outer margin and apex, and with a dark discal spot.

Hindwings. Hindwings broadly rounded. Uppersides of the hindwings white, or yellow, or primrose; usually more or less conspicuously patterned; with a conspicuous discal mark (represented as an orange spot); coloured like the forewings, but the border is sometimes less conspicuous.

Undersides of wings. Undersides of the forewings with a conspicuous black discal spot; paler than the upperside, basally and discally whitish to primrose, yellow or orange-ish, and the apex and outer margin not blackish but yellow with a subterminal row of blackish or reddish spots.

Undersides of the hindwings pale to dark yellow, basally suffused blackish in C. hyale; with a reddish mid-costal mark, a subterminal row of redish spots, and a conspicuous, characteristic eye-spot discal mark: “closely resembling a faded clover leaf with a central fungus-spot when the insect is at rest” (Meyrick); eye-spotted. The eye-spots 1; more or less central. Undersides of the hindwings with a conspicuous discal mark (this shaped like a figure ‘8’, comprising two adjoining, red-or orange-bordered white spots).

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; vein 2 departing from the cell less than three-quarters of the distance from its base (from about halfway). Veins 2–5 well separated on the cell, then a long stalk to where 7 diverges from 6, with 8 diverging halfway along or distally from 7, 9 from the 6+7 stalk or almost connate with it on the cell, 10 separate from the mid-region of the cell, 11 free (Meyrick treated this layout as “vein 7 absent”).

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. 7 veins arising from the hindwing cell. The cell-derived hindwing veins all arising independently of one another.

Eggs, larvae, pupae. Eggs truncate-fusiform; longitudinally ribbed. The larvae having no known association with ants; hairy; exposed feeders. On herbaceous Papilionaceae - Trifolium, Lotus, Melilotus, etc.

Pupae ridged and angular; conspicuously patterned; without shining-metallic markings; exposed, with no coccoon; not suspended, but attached at the tail and secured by a median girdle of silk.

British representation. 5 species. Colias alfacariensis (Berger’s Clouded Yellow), Colias hyale (Pale Clouded Yellow), Colias croceus (Clouded Yellow), Colias palaeno (Moorland Clouded Yellow). The adults abroad May to June (immigrant individuals), or August to September (their offspring).

Status in Britain. Common occurrence in Britain entirely reflecting regular immigration (C. croceus, C. hyale), or rare ocurrence representing occasional, genuine immigrants, or adventive (the ‘British’ status of C. alfacariensis and C. palaeno being uncertain).

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

Comments. Strong fliers.

Classification. Superfamily Papilionoidea. Pieridae.

Illustrations. • Colias croceus (Clouded Yellow), C. hyale (Pale Clouded Yellow), C. alfacariensis (Berger’s Clouded Yellow): photos. • Colias hyale (Pale Clouded Yellow: B. Ent. 242). • Colias hyale (dissections: B. Ent. 242). • Colias hyale: B. Ent. 242, legend+text. • Colias hyale: B. Ent. 242, text cont.. • Colias croceus (Clouded Yellow): both sexes and var. helice. Stephens (1828). • Colias croceus (Clouded Yellow: Kirby, 1907). • Colias palaeno (Moorland Clouded Yellow: Kirby, 1907). • Colias palaeno (Mooland Clouded Yellow): Hübner, 1805.. • Colias hyale (Pale Clouded Yellow) and ?Colias palaeno (Moorland Clouded Yellow, adventive): Stephens (1828). • Larvae of C. croceus (with pupa) and C. hyale: Duponchel (1849). • Colias hyale (Pale Clouded Yellow): larva. • Colias croceus (Clouded Yellow): egg, larva, pupa. • Colias, Leptidea: neuration.

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.’.