Butterfly

Butterfly, the common name of a group of insects forming the sub-order of Lepidoptera known as the Rhopalocera. The term is, however, rather loosely applied to other insects of similar appearance, belonging to other orders, and the differences between the butterflies and moths are not constant. By restricting the name to those Lepidoptera which have club-shaped antennae or feelers, which fly by day, and in which the two pairs of wings are not linked together by a bristle, it can be used as synonymous with Rhopalocera. Except in the above characters and some habits, such as closing the wings when at rest, the butterflies are so much like the moths that the description of the anatomy of the Hawk-moth (q.v.) suffices for the structure of this sub-order. There are only about seventy British species, and none are more than about two and a half inches broad. The group is essentially tropical: some of the largest, as some of the Ornithoptera(q.v.), are over nine inches in expanse of wing. The main character upon which the sub-order is divided is the condition of the anterior pair of legs; thus in the Nymphalidae (q.v.) they are rudimentary, e.g. the Fritillaries, Purple Emperor, etc.; in the Papilionidae (q.v.) all the legs are perfect, e.g. the Cabbage-butterfly, Swallow-tail, etc., while in the Lycaenidae, such as the Coppers and Blues, those of the male may only be slightly imperfect. The oldest known butterflies occur in the Oolitic rocks.