Swallowtail butterfly

Swallowtail butterflies are large, colorful butterflies in the family Papilionidae, and include over 550 species. Though the majority are tropical, members of the family inhabit every continent except Antarctica. The family includes the largest butterflies in the world, the birdwing butterflies of the genus Ornithoptera. Swallowtails have a number of distinctive features; for example, the papilionid caterpillar bears a repugnatorial organ called the osmeterium on its prothorax. The osmeterium normally remains hidden, but when threatened, the larva turns it outward through a transverse dorsal groove by inflating it with fluid. The forked appearance of the swallowtails' hindwings, which can be seen when the butterfly is resting with its wings spread, gave rise to the common name swallowtail. As for its formal name, Linnaeus chose Papilio for the type genus, as papilio is Latin for 'butterfly'. For the specific epithets of the genus, Linnaeus applied the names of Greek figures to the swallowtails. The type species: Papilio machaon honored Machaon, one of the sons of Asclepius, mentioned in the Iliad. Further, the species Papilio homerus is named after the Greek poet, Homer. The genera of extant swallowtails are usually classified into three subfamilies, Baroniinae, Parnassiinae, and Papilioninae, the latter two being further divided into tribes. In swallowtails, besides morphological characteristics, the choice of food plants and ecological lifestyle reflect phylogeny and classification. The Baroniinae are a monotypic subfamily, restricted to a very small region in Mexico and are considered to be the most basal of the subfamilies. Baronia brevicornis is considered to be a relict species, and shares features with a fossil taxon Praepapilio. Baronia is unique among papilionids as having an Acacia species (family Leguminosae) as its food plant. Subfamily: Baroniinae. The Parnassiinae are a subfamily of essentially Holarctic butterflies. The vast majority of species, mostly Parnassius, can be found in mountain habitats. Parnassiinines can also be found in other habitats such as 'arid deserts (Hypermnestra), humid forests (Luehdorfia) and even lowland meadows (Zerynthia)'. The tribes recognized in the Parnassiinae are Parnassiini, Zerynthiini, and Luehdorfiini. Tribe Parnassiini contains two genera, Hypermnestra, largely confined to central Asia and the genus Parnassius (the Apollos), a distinctive group of many species, all of which are alpine and capable of living at high altitudes. Most Parnassius have two small reddish spots on their hindwings. The tribe Luehdorfiini contains the genera Archon of Asia minor and the genus Luehdorfia of China and Japan. These two tribes have evolved to change their food plants, while the third tribe, Zerynthiini, has retained the archetypical papilionid food plant, the lowland vine Aristolochia. Zerynthiini comprises four genera – Sericinus, Bhutanitis, Zerynthia and Allancastria.:13