UK Butterflies

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Short-tailed Blue

Cupido argiades

kew-PY-doh ar-jee-AY-deez

Wingspan
20 - 30 mm

Checklist Number
61.011

Short-tailed Blue

Cupido argiades

kew-PY-doh ar-jee-AY-deez

Wingspan
20 - 30 mm

Checklist Number
61.011


This butterfly is one of the rarest immigrants to the British Isles with only 17 records in total. The first acknowledged specimens were seen on 18th and 20th August 1885 on Bloxworth Heath in Dorset, leading to the species' earlier name of the Bloxworth Blue. However, it subsequently turned out that a pair had been seen in a small quarry near Frome in Somerset in 1874. Half of all records were recorded in 1885 and 1945, two exceptional years for immigrants. All records come from southern England and the Channel Islands and most records have been recorded from a relatively-small area that encompasses east Dorset, west Hampshire and south Somerset. It has been suggested that these individuals have flown the channel from the heaths of Brittany in northern France, where the species can be abundant.

This species was first defined in Pallas (1771) as shown here (type locality: Samara, Russia).

Description to be completed.

This species is a rare migrant to Britain and/or Ireland.

1.2 Rare Migrant

Description to be completed.

No conservation action is relevant for this species.

All individuals found in the British Isles have occurred between July and September.

Description to be completed.

Description to be completed.

"All the eggs laid on July 24th, 1904, hatched on July 30th, remaining six days in the egg state. The egg is very small, being exactly the same in diameter as the egg of L. minima, i.e., 0.40 mm., and 0.20 mm. high. It resembles the egg of L. Icarus in shape, being of a compressed circular form and of a clear pale greenish-blue colour, but it varies both in extent of the ground colour and in the structure of the reticulations, which are white, resembling frosted glass, and cover the whole surface in an irregular network pattern; in some the pattern is almost like ordinary network, forming squares; while others have triangular cells, but all are irregular, and some have the juncture of the reticulations much more prominent than others. The upper surface is very slightly sunken, being almost flat, with a somewhat irregularly formed micropyle, which is darker and without the frosted appearance which covers the whole of the surface excepting the base; the reticulations on the depressed part of the crown are simple, being without the raised knobs at the junctures; those surrounding the side are prominent, but diminish on nearing the base; the cells between the reticulations have a fine granular surface." - Frohawk (1924)

Despite Frohawk's descriptions, the larva actually has four, and not five, instars.

"During their earlier stages the larvae are decidedly cannibalistic. One larva was noticed, after the first moult, feeding on a newly-hatched larva, which it seized as it emerged from the egg; but during the last two stages they did not appear to attack each other, which agrees with the cannibalism of L. arion." - Frohawk (1924)

The primary larval foodplants are Common Bird's-foot-trefoil (Lotus corniculatus) and Gorse (Ulex europeaus).

1st Instar

"The larva makes its exit by eating the crown, as well as a portion of the side of the egg-shell. Directly after emergence the larva is exceedingly small, being only 0.60 mm. long; it is similar to other young Lycaenidae larvae in having a slight medio-dorsal furrow and sloping sides, and furnished with rows of long white serrated hairs, four dorsal and three lateral on each segment; those on the dorsal surface are in pairs on each side of the furrow; both curve backwards, the anterior one being very long; below these are two lenticles outlined with dark olive, and below a pair of small dark tubercles bearing a club-shaped hair, excepting on the sixth, seventh and eighth segments, which only have hairs on the posterior ones; the sub-spiracular row of hairs consists of three long ones on each segment, projecting laterally, each having a dark base; along the ventral surface are similar serrated hairs, and shorter ones on the claspers. The head is greenish-olive and black, and the body of a pale ochreous yellow in shadow and pale grey in high light; to the naked eye it appears whitish; the entire surface is sprinkled with black points. They are very active when first hatched, crawling rapidly for such small creatures, and feed on various parts of the plant. One was seen feeding with its anterior half buried into the end of a stem which had been cut off." - Frohawk (1924)

2nd Instar

"The first moult on August 3rd, the first stage only lasting four days. Shortly before first moult it measures only 1.6 mm. long. During the early stages these larvae, like the other Lycaenidae, require the greatest attention to distinguish their changes, on account of their very small size and similarity of stages, and unless most carefully watched under a lens it is practically impossible to detect their moults. After the first moult, six days old, it measures only 2.12 mm. long. The body is considerably humped dorsally from the second to ninth segments, the first, tenth, eleventh and twelfth being rather compressed. There is a decided lateral ridge. The surface is finely granulated, and studded all over with serrated hairs of various lengths; those along the dorsal and lateral regions are longest and curved. All are whitish (excepting those on the sub-dorsal surface, which are dusky) with bulbous bases, from which rise thorn-like spikes, each base forming a star; there are also numerous lenticles scattered over the body. The general colour is a pale yellow, with a medio-dorsal longitudinal brownish stripe, oblique brownish stripes, and a rust-coloured sub-spiracular line, bordered laterally by whitish; the head is shining black and beset with a few fine whitish hairs. Other forms occur, having a generally greenish ground colour with slightly darker markings. The larvae which subsequently hibernate are similar to the above when in the same stage, i.e., after the first moult." - Frohawk (1924)

"As the larvae that hibernate do not assume the green colouration during the last three stages, but acquire a generally ochreous-fulvous hue, resembling the brown withered foliage during hibernation, it is perhaps necessary to add the following description of the hibernating form: After the second moult the ground colour is pale ochreous-green; the medio-dorsal and lateral stripes are rich purple-brown and the oblique stripes are paler. The colouring remains similar until after the fourth and last moult, and when fully grown the ground colour is a very pale pinkish-ochreous, the medio-dorsal stripe is deep purplish-brown, the lateral stripe light chocolate-brown, and the oblique side stripes light rust-colour. They remain so coloured during hibernation. As the larva developed, all the green colouring gradually disappeared, and during the last stage no green form existed in any of those that entered into hibernation. No brown form occurred in the last stage of any of the larva reared from eggs laid July 24th, 1904, although when young (after the first moult) two distinct forms appeared, one being striped with brown, the other entirely green with very slightly darker green markings. After each subsequent moult the striped forms gradually lost the markings, and after the last moult all were entirely green, excepting a few which had the lateral ridge tinged below with pinkish-brown. Some of the larvae hibernated in the dead rolled-up leaves of Lotus corniculatus, and some low down on the stems of the plant, upon which they spun a fine layer of silk to rest upon. The larva in question entered into hibernation about the end of September, after the fourth and last moult, and fully grown." - Frohawk (1924)

3rd Instar

"The second moult on August 7th. After second moult, nine days old, it is 5 mm. in length, very similar to the previous stage, but on the tenth segment is a rudimentary honey gland or one of indistinct formation, surrounded by minute star-like processes, and a fringe of delicate white spines or bristles, each bearing a tuft of spine-like hairs, extremely fine, similar in construction to those bordering the gland of arion larva. Both forms now more closely resemble each other, the brownish marked form assuming a generally green colouring with only a faint pinkish lateral line. The hibernating larva: the stripes become deeper in colour and the ground colour less green. In this stage they greedily feed on the seeds of Medicago lupulina, eating through the capsule, and devouring the contents, but they appear to feed mostly at night." - Frohawk (1924)

4th Instar

"The third moult occurred on August 12th. After the third moult, eighteen days old, it is 6.3 mm. long. The ground colour is a beautiful clear green, with a darker green medio-dorsal furrow, and three longitudinal rows of oblique dull green side markings, and a waved dull green lateral band bordered below by a pale line, and faint dull brownish-pink streaks; the whole surface is thickly sprinkled with serrated hairs of different lengths; those bordering the dorsal furrow are the longest; they vary from white to ochreous brown, and have similar swollen star-like bases, which vary in form and colour: some are brownish, others white, resembling little glass petals. As in the previous stage, numerous lenticles are scattered over the surface; the spiracles are prominent and outlined with brown. In this stage they feed as much by day as by night, but are much slower between the moulting, occupying eleven days from the third to fourth moults. The gland on the tenth segment is now more distinct, but surrounded with similar processes and bristles. No green form exists in this stage in the hibernating larvae." - Frohawk (1924)

"Fourth and last moult, on August 23rd. After fourth moult and fully grown it measures 9.5 mm. long. It is of the usual onisciform shape, with slightly flattened sides, and with only a very shallow dorsal furrow, bordered each side by a fringe of spinous bristles, slightly serrated and varying in length; the whole surface is densely studded with shorter but similarly formed bristles, which vary much in length and colour from white to pale brown; each, including the longer dorsal ones, have wonderfully formed bases (similar but more pronounced than in the previous stage) composed of a bulb-centred star, the points rising from the base; some are wholly white, others olive-green; there are also numerous shining whitish-green lenticles outlined or set in black rings more or less starred, of various sizes, and scattered over the whole surface; the spiracles are whitish, outlined with brown, and the inner edge dentated. The gland on the tenth segment is similar to that in the previous stage, being a small elongated transverse fissure, and fringed with fine white bristles as described. Although so similar in formation to the gland of arion, the author has been unable to detect any liquid exuding from it when touched; also it appears less sensitive to irritation. On the eleventh segment is a sub-dorsal, partly retractile, whitish tubercle. The ground colour is pale green, with a darker green medio-dorsal stripe, and oblique side stripes of a fainter green; in some specimens the lateral ridge is tinged below with pinkish-brown; the head is black and shining, and is hidden under the overlapping first segment, except when extruded while feeding and crawling. The ground colour of the hibernating larva is pale pinkish-ochreous, striped with brown and rust-colour ... During the last stage the larva were supplied with both common white and red clover blossoms, which they greedily devoured. One larva completely ate up the whole of the petals of a red blossom in two days; it appeared to be feeding continually both day and night. They also readily feed on the flowers, seeds and leaves of Lotus corniculatus." - Frohawk (1924)

"The pupa is attached to the food plant by the cremastral hooks to a pad of silk and a cincture round the body; all were attached to the centre of the leaves; the general resemblance both in form and colour between a decaying lotus leaf and the pupa is very marked ... The pupa measures 8.5 mm. long, of fairly uniform thickness. The head is truncated in front, the thorax slightly swollen dorsally; the abdomen rises at the base, and falls away in a gentle curve to the anal extremity, and is bluntly terminated. The entire surface is a pale green, and very finely reticulated; the wings are rather whiter green than the rest of the body, with whitish neuration, and irregularly sprinkled with minute black specks; a medio-dorsal line composed of a series of black marks and specks runs the entire length, and forms a well-defined line over the head and thorax, but becomes broken up into a series of spots on a darker ground stripe along the abdomen; there is also a super-spiracular series of small black spots, one on each of the third, fourth, fifth and sixth segments, and a large and somewhat oval black blotch on the first abdominal segment; and two others, one at the base of the wing on the meso-thorax, another on the meta-thorax, also a small spot on the pro-thorax; all these and a few other tiny specks sparingly sprinkled over the body are black. The whole surface excepting the wings is sprinkled with slightly curved, moderately long, white serrated hairs, each with a swollen base; near the base of the wings are a few fine white bristles terminating in a cluster of much finer bristles. The spiracles are whitish and prominent. The honey gland of the larva is represented in the pupa by two short but rather deeply incised scars. It remains from about ten to fourteen days in the pupal state, according to temperature." - Frohawk (1924)