Swallowtail butterfly 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
Serial comma to "The Oxford Companion to the English Language", "Commas are used to separate items in a list or sequence … Usage varies as to the inclusion of a comma before "and" in the last item … This practice is controversial and is known as the serial comma or Oxford comma, because it is part of the house style of Oxford University Press." Some use it only where necessary to avoid ambiguity, in contrast to such guides as "Garner's Modern American Usage", which advocate its routine use to avoid ambiguity. Common arguments "for" consistent use of the serial comma: Common arguments