UK Butterflies
Building a Community of Responsible Butterfly Enthusiasts in Britain & Ireland
Building a Community of Responsible Butterfly Enthusiasts in Britain & Ireland
Wingspan
♂ 32 - 34 mm, ♀ 36 - 42 mm
Checklist Number
61.008
The Long-tailed Blue is an extremely rare migrant to the British Isles. It was first recorded from Brighton in East Sussex, and Christchurch in Hampshire, in August 1859. By 1939 a mere 36 sightings had been recorded - mostly of individuals. Between 1940 and 1988 another 85 sightings were recorded. The only major immigration was in 1945, a good year for migrants in general, when there were 38 sightings. A recent immigrant was observed in Hampshire in 2006.
However, the most noticeable influx occurred in 2013 when Long-tailed Blue were seen at 9 sites in Devon, Hampshire, Sussex, Kent and Suffolk. Mating pairs, eggs and larvae were also found, confirming that the species had successfully bred and, on 8th September 2013, the first of the offspring emerged in Wiltshire and Kent. Sightings from other counties followed, with sightings continuing into October.
On the continent, this butterfly is considered a pest of pea crops, one of the larval foodplants, where it can cause considerable damage. This butterfly is continuously-brooded on the continent but is unable to survive our winters. Although this species is a rare migrant to the British Isles, it is one of the most-widely distributed Lycaenids in the world. The vast majority of records in the British Isles are from the south of England and the Channel Islands.
| Family: | Lycaenidae | Leach, 1815 |
| Subfamily: | Polyommatinae | Swainson, 1827 |
| Tribe: | Polyommatini | Swainson, 1827 |
| Genus: | Lampides | Hübner, [1819] |
| Subgenus: | ||
| Species: | boeticus | (Linnaeus, 1767) |
Description to be completed.
This species is a rare migrant to Britain and/or Ireland.
| 1.2 Rare Migrant |
The adult butterfly is most-often seen flying around garden flowers, especially those which are potential foodplants. However, it may also be found on open downland.
No conservation action is relevant for this species.
The butterfly is rarely seen before the second half of July, with the peak of sightings being recorded at the end of August and into September.
The adult butterfly has a jerky and rapid flight that is very similar to a hairstreak, but flies closer to the ground. It is also a strong flyer, borne out by its ability to migrate over large expanses of land and water. This butterfly possesses a pair of "tails" that give this species its name, together with an eye spot where the tails meet the wings. These act to divert a predator, such as a bird, away from the essential body parts. When at rest, the butterfly will rotate the hindwings which causes the tails to move, diverting predators from the more-important parts of the body.
Description to be completed.
This butterfly is known to have bred in the British Isles and 26 eggs were first found near Dorking in Surrey on 12th July 1952 from the flowers of Broad-leaved Everlasting-pea. The eggs hatch after around a week.
"The first eggs laid, on August 9th, hatched on the 16th, remaining in the egg state seven days ... The eggs were laid singly on the basal parts of the flowers and buds ... The egg is very small, being only 0.50 mm. in diameter and much less in height, of a compressed spheroid form; the centre is rather concave and the micropyle finely granulated and sunken; the whole surface is covered with fine reticulations, which form an irregular pattern over the crown, and which gradually increase until, turning over the brim, where they spread out into a fine network pattern composed of knobs arranged at fairly equal distances, each one radiates six raised ribs, forming a beautiful hexagonal pattern; these on nearing the base again break up into irregular cells. The ground surface is very finely granulated. When first laid, the crown is not at all sunken, but after twenty-four hours a slight depression is formed. The colour at first is a clear bluish-green white, which gradually fades until just before hatching, when it is wholly whitish." - Frohawk (1924)
The woodlouse-shaped larva first feeds on the flowers of the foodplant, but eventually enters a pod where it feeds on the contents. This stage lasts between 3 and 4 weeks.
The primary larval foodplants are Bladder-senna (Colutea arborescens), Broad-leaved Everlasting-pea (Lathyrus latifolius) and Broom (Cytisus scoparius).
"Upon hatching, the larva rapidly eats away the crown, making a circular hole, and emerges; it at once becomes very active, crawling rapidly for so tiny an object. Directly after emergence, the larva is very small, being barely 0.80 mm. long. The body is almost cylindrical, showing no medio-dorsal furrow. On the first and last segment is a dorsal disc of a shining pale olive colour. From the second to eleventh segments inclusive, are two dorsal rows of rather short whitish finely serrated hairs with shining black bulbous bases, one pair only on each segment placed sub-dorsally and curving slightly backwards; below each are two lenticles; the anterior one is much the larger, with a clear ochreous disc, the other much smaller, black and shining; below the larger is another hair similar in structure to the dorsal one, but with a much smaller base; the spiracle is rather prominent, with a very small aperture; directly below the spiracle are two other similar hairs, both projecting laterally, and another on the lateral lobe; these are all very finely serrated and blunt-tipped; those on the claspers and ventral surface are white, simple and finely pointed. The head is shining olive, with black mouth parts and whitish eye spots. Both the first and last segments are beset with hairs, but they are rather longer than those on the rest of the body, especially those on the anal segment, which project backwards. The ground colour of the entire body and claspers is a pale citrine-yellow; the whole surface is densely covered with darker raised points. Soon after hatching, a few entered the calyces and fed on the base of the petals. Also one fed on the tender young leaf-spine of furze. Other young larva supplied with broom blossoms, quickly bored into the centre of the buds through the petals, leaving only a minute hole where they entered; the flower buds of Spartium junceum are eaten in a similar way." - Frohawk (1924)
"The first moult took place within a week after emergence. After the first moult it measures 2.5 mm. long. The whole surface is rather thickly sprinkled with finely serrated blackish hairs with whitish tips and pale bulbous bases, varying much in size; on the first segment is a dorsal fan-shaped dusky-olive disc; the head is olive and beset with hairs. The ground colour is pale olivaceous-yellow densely covered with minute dusky points; spiracles black. A few prominent lenticles are dotted over the dorsal surface chiefly above the spiracle. A rust-brown medio-dorsal band extends the entire length, and there are oblique side markings of the same colour. In this stage they are very active and great cannibals." - Frohawk (1924)
"After second moult, thirteen days old, it measures 8 mm. long, having increased in size enormously during this stage. They appear to be almost continuously feeding. One placed on a flower bud of everlasting pea within a few minutes bored into the centre and disappeared. They also bore into the pods and feed on the young peas; they also feed on various parts of the blossoms. The ground colour is a pearly whitish, somewhat inclined to a yellowish tinge. There is a medio-dorsal purple-brown band, broken up by the segmental divisions, and by the large honey-gland on the tenth segment, which is unicolourous with the rest of the body. The band begins on the anterior edge of the second segment, and is continuous over the last three segments from the edge of the gland. A double sub-dorsal series of oblique markings, two on each segment, checker the side; these and a broad spiracular band are of a lilac-brown; the black spiracles are encircled with white. A pearl-white lateral band is continuous round both the anterior and posterior segments; this is bordered below by a light brown stripe; the rest of the ventral surface, including the claspers, is pearl-white; the legs black; the head is shining black and small in proportion to the size of the larva before the third moult, and is set on a pale yellow retractile neck, capable of considerable protrusion, but while resting the head is withdrawn under the hood-like anterior segment. The whole of the dorsal surface is rather densely clothed with somewhat short black serrated bristles, slightly curved and sharply pointed, each mounted on a pedestal base bearing minute spines. The colouring of the larva varies in different specimens; some are more heavily marked than others. On the anterior segment is a diamond-shaped dorsal disc. The larva eats its cast skin after each moult, except the first." - Frohawk (1924)
"After third and last moult, fully grown, it measures from 15.9 mm. to 19 mm. when extended crawling. The body is less arched than in most Lycaena larvae, gradually decreasing posteriorly where it is compressed dorsally. The segments are moderately humped, but there is no central furrow. The first segment is projecting and rounded, the anal segment much flattened. The head is highly polished, of an amber-brown colour, with black clypeus and eye spots, and mottled black at base, lip white. The colour of the body varies from pale ochreous-green to grass-green; some are decidedly olive in hue. The markings agree in tone with the ground colour. A dark medio-dorsal band extends from the front of the second segment to the anal extremity, slightly narrowed over the eighth and ninth segments. Wavy oblique stripes cover the sub-dorsal surface, three on each segment, the last reaching the flesh-coloured spiracle; a pale yellowish lateral stripe extends down the sides and round both extremities; the legs brown, claspers pale. On the first segment is a sunken dorsal disc, and a well developed honey-gland. on the tenth segment and a retractile tubular tentacle on each side of the eleventh segment behind and below the spiracle. The whole of the dorsal surface is densely clothed with minute serrated spines, each rising from a starred base; the majority are ochreous with black bases, others are wholly white; the latter are more numerous on the paler coloured larvae; besides these, the body is sprinkled with lenticles. On the dorsal surface of the tenth and eleventh segments the spines are reduced into club-shaped processes; these again become developed into serrated spines on the anal segment, and into longer whitish hairs laterally. When fully grown and ready for pupation, the larva assumes a dull lilac-pink hue. One that fixed for third moult on June 26th moulted the next day and became fully grown July 5th, remaining in the last stage eight days; another which moulted on June 28th spun up for pupation on July 6th, also being eight days in the last stage. During the last stage they greedily feed on garden peas, boring through the pod, living in the interior and devouring the peas; if the pod is opened the larva spins a delicate but dense web over the aperture. The larva usually selects a curled-up withered leaf for a puparium, in which it spins a layer of silk as well as a covering of silk over the opening between the folding-up edges, also a girdle round its body; it then settles down for pupation, which occupies three days. One that spun up on July 7th pupated July 10th." - Frohawk (1924)
The pupa is attached to withered leaves by a girdle. This stage lasts around 10 days.
"The pupa measures from 10.5 mm. to 12.7 mm. long. The head rounded, the meso-thorax swollen dorsally, sunken at meta-thorax, the second abdominal segment swollen; the abdomen then runs in a slight curve to the fourth segment, then more abruptly curved, forming a conical point; the wings are slightly bulging near the apex; at the base of the wing is a slight angular projection; otherwise it is smooth and rounded generally. The entire surface is covered with very fine raised reticulations, and sprinkled with dark brown lenticles along the spiracular region and a very few minute bristles. The anal segment is without any hooks; the spiracles are the same colour as the body, therefore are very inconspicuous (not black as stated by authors). The abdomen is, however, spotted with deep purplish-brown forming a super-spiracular series; other dorsal spots and blotches are spread over the surface, especially on the thorax; the whole of the surface is more or less speckled with dark brown, and a medio-dorsal dusky stripe extends from the head. The ground colour at first is a pale flesh, gradually becoming paler, and when mature is a pale creamy-ochreous. They vary considerably in the amount of markings; some are only sparsely speckled, while others are heavily spotted and blotched. When the imago is developing prior to emergence, the eyes are the first to change colour by turning dark brown, the wings become opaque creamy-buff, and the thorax brown; the whole of the pupa except the ventral half of abdomen assumes a dull black with a slight iridescent greenish-blue tinge in the centre of the wing. The pupa is attached by a silken girdle and sometimes by a few loose strands of silk over it, but being without cremastral hooks it is not attached by the anal extremity. One that pupated on July 10th emerged on July 20th, 1912, remaining ten days in the pupal state." - Frohawk (1924)
The following links provide additional information on this butterfly.
