Swallowtail butterfly

Swallowtail butterflies are large, colorful butterflies in the family Papilionidae, which includes over 550 species.[1] Though the majority are tropical, members of the family occur on every continent except Antarctica. The family includes the largest butterflies in the world, the birdwing butterflies of the genus Ornithoptera.[2] Swallowtails have a number of characteristic features; for example, on the prothorax a Papilionid caterpillar bears a repugnatorial organ called the osmeterium. The osmeterium normally is hidden, but when threatened, the larva everts it through a transverse dorsal groove[3] by inflating it with blood. It is a fleshy, forked structure and emits smelly secretions containing terpenes, which the larva typically tries to smear onto any attacker touching it. The adults of some species have conspicuous posteriad prolongations of the hind wings in the region of the M3 vein. The forked appearance of these features as seen in the butterfly when resting with its wings spread, gave rise to the common name swallowtail. As for the formal name, Linnaeus chose Papilio for the type genus, Papilio being the Latin for a butterfly. For the specific epithets of the genus, Linnaeus applied the names of Greek heroes to the swallowtails. The type species: Papilio machaon honoured Machaon, one of the sons of Asclepius, mentioned in the Iliad. As of 2005, 552 extant species have been identified[1] which are distributed across the tropical and temperate regions of all continents except Antarctica. Various species occur from sea level to high mountains, as in the case of most species of Parnassius. The majority of swallowtail species and greatest diversity in form and lifestyle are found in the tropics and subtropical regions between 20N and 20S,[5]: particularly Southeast Asia, and between 20N and 40N in East Asia. Only 12 species are found in Europe[6] and only one species, Papilio machaon is found in the British Isles.[7] North America records 40 species which include tropical species and Parnassius.[8] The northernmost swallowtail is the Arctic Apollo (Parnassius arcticus) which is found in the Arctic Circle in northeastern Yakutia, at an altitude of 1500 meters above sea level.[9] In the Himalayas, various Apollo species such as Parnassius epaphus, besides others, have been recorded to occur up to an altitude of 6,000 meters above sea level.[10]:221 [edit]Morphology The detailed descriptions of morphol

gical characteristics of the Papilionidae, as quoted in Bingham (1905) are as follows:[11]:1,2 Egg. "Dome-shaped, smooth or obscurely facetted, not as high as wide, somewhat leathery, opaque." (Doherty.) Larva. Stout, smooth or with a series of fleshy tubercles on the dorsum : sometimes with a raised fleshy protuberance (the so-called hood or crest) on the fourth segment which is also generally thickened above. The second segment has a transverse opening, out of which the larva can protrude at will an erect, forked, glandular fleshy organ that emits a strong, somewhat pleasant, but always penetrating odour. Pupa. Variable in form but superiorly most often curved backwards, sometimes very strongly so ; angulate, with the head truncate or rounded, often bifid ; back of abdomen smooth or tuberculate. Attached by the tail, normally in a perpendicular position, and further secured by a silken girth round the middle. In Parnassius strangely enough the pupa is placed in a loose silken web between leaves. Imago. Wings extraordinarily variable in shape. Hind wing very frequently with a tail, which may be slender, or broad and spatulate, but is always an extension of the termen at vein 4. In one genus, Armandia, the termen of the hind wing is prolonged into tails at the apices of veins 2 and 3 as well as at vein 4. Pore wing (except in the aberrant genera Parnassius and Hypermnestra) with all 12 veins present and in addition a short internal vein, vein 1 a,[12] that invariably terminates on the dorsal margin. There is also a short transverse vein present at base of wing between the median vein and vein 1a in all genera except Leptocircus, Armandia, Parnassius, and Hypermnestra. Hind wing : vein 1a absent; precostal vein and precostal cell both present; dorsal margin not excavated so as to receive the abdomen, but in the male frequently folded over and studded within the fold with specialized scales (androconia) or hairs that are often strongly scented. Antennae comparatively short, with generally a distinct club; "the distal joints mostly more expanded ventrally than dorsally, so that the club is curved dorsad" (Jordan). The scaling most extended in Leptocircus, but in Papilio confined to the basal joints. Body stout; claspers at apex of abdomen in the male generally well-developed, absent in a few forms. Six walking legs; the fore tibiae with a medial pad; claws simple except in one form of Leptocircus, which has them bifid.