The Large blue (Phengaris arion) is a species of butterfly in the family Lycaenidae. The species was first defined in 1758 and first recorded in Britain in 1795. In 1979 the species became mostly extinct in Britain but has been successfully reintroduced with new conservation methods. The species is classified as "near threatened" on the IUCN Red List of Threatened Species. Today P. arion can be found in Europe, the Caucasus, Armenia, western Siberia, Altai, north-western Kazakhstan and Sichuan. The large blue can be distinguished by its unique speckled black dots on its wings with a blue background. The large blue butterfly is well known in behavioural ecology as it is a brood parasite of a single species of red ant, Myrmica sabuleti. The discovery was made by Captain Edward Bagwell Purefoy along with F. W. Frohawk and others.
Subspecies P. a. arion Mainland Europe, western Siberia, Altai, north-western Kazakhstan P. a. delphinatus (Fruhstorfer, 1910) P. a. zara (Jachontov, 1935) Caucasus, Armenia P. a. buholzeri (Rezbanyai, 1978) † P. a. eutyphron (Fruhstorfer, 1915) formerly southern Britain
Description Large blue caterpillars grow to about half an inch (13 millimetres) in length, and spend up to 9 months before they undergo metamorphosis to a chrysalis to become a butterfly. Large blue butterflies are one of the largest in the family Lycaenidae, known as the gossamer-winged butterfly, with a wingspan of up to 2 inches (51 millimetres), and live only for a few weeks. The wings of the large blue butterfly are speckled with black dots.
Description by Seitz
L. arion L. (83 c). Larger, above of a lighter and more shining blue [than arcas], with a row of black spots across both wings, the spots being sometimes obsolete only on the hindwing of the male. At once recognized by the large number of ocelli on the underside, especially on the hindwing, and by the bright blue dusting of the base beneath. Europe and Anterior Asia, from North Europe, the Baltic provinces, and England to the Mediterranean (Corsica), and from Spain to Armenia and South Siberia. In ab. unicolor Hormuz. the upperside is entirely blue, all the black spots with the exception of the discocellular one being absent. ab. Arthurus Melvill is without ocelli beneath. In ab. jasilkowskii Hornuz the ocelli are absent beneath in the cell as in euphemus, from which this aberration is at once distinguished by its blue-green basal scaling on the underside. In ab. coalescens Gillm. the black spots of the upperside are confluent. — Quite a number of local forms have been separated Northern specimens, which are feebly spotted, are named alconides by Aurivillius. — obscura Christ. (83 c) is an alpine form in which the whole outer half of the wings above is black or dark brown; it occurs typically in the High Alps, being locally very plentiful, e. g. at Bergun, Zermatt, Stilvio and at many places in the Alpes Maritimes. This darkened form occurs also in the Ural (= ruehli Krulik.) — In the South two aberrant forms have been found, namely ligurica Wagn., at the Eiviera between San Remo and Bordighera, with a conspicuous row of white marginal ocelli on the upperside of the hindwing, and aldrovandus S. L., from the Vesuvius, the underside darkened with brown. — cyanecula Stgr. [ now species Phengaris cyanecula (Eversmann, 1848)] (83 d) is an Asiatic form, from the Caucasus to Mongolia, with the metallic blue green dusting of the hindwing beneath being abundant, bright, and extending almost to the distal edge. — Egg very flat semiglobular, pale bluish white, deposited on Thymus which just begins to flower. Larva adult pale ochreous, with a pale lilac tinge at the sides; head ochreous, marked with black anteriorly; prothoracic plate black; feeds until the autumn on Thyme, then disappears and is found full grown the next June in the nests of ants. It is therefore suggested that the ants feed it up (Frohawk) and perhaps also protect the pupae. The chrysalis the colour of amber except for the wing-cases, smooth, somewhat elongate, without web. The butterflies occur usually singly, being locally frequent on open ground, on broad roads through shrubby woods, flying about 1 m above the ground. They rest with closed wings, particularly on Thymes and Scabious. On the wing from the end of June into August.
Distribution The large blue butterfly is found from coast to coast of the Palearctic realm, but is most concentrated in the areas from France to China.
Habitat
The habitat of the large blue butterfly is largely influenced by location of its food sources. The species requires a combination of abundant amounts of its larval food plant, Thymus drucei and the presence of Myrmica sabuleti ants in order to survive. It has also been found that an underlying key factor for the survival of the large blue is site heterogeneity. The butterfly is most abundant in pastures and abandoned areas of diverse vegetation and shrubbery. This preference can be explained by examining the result of a uniform landscape. A constant landscape synchronizes many biological activities including flowering of host plants, adult emergence dates, or larval pressures on the ant colonies. If important biological functions take place at the same times, the population becomes much more susceptible to random unfortunate events such as environmental disasters. Thus traditional farming acts to desynchronize the biological system, and allows for re-colonization of patches that are temporarily untouched. The presence of differing sites and varied ecological structures provides differing microclimates that can make a huge impact on the survival of the large blue butterfly.
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