LEPIDOPTERA, the name used in zoological classification for that order of insects which comprises the butterflies and moths. The term (Gr. Xeris, a scale, and rrEp6P, a wing) was first used by Linnaeus (1735) and has been retained by all naturalists after him. Lepidoptera are among the most familiar and easily recognizable of insects and have long been popular objects for study and collecting, largely on account of the great beauty of coloration exhibited by so many of the species, together with the interest that is afforded by following their transformations. Their most easily observable characteristic is the scaly covering of the wings, body and appendages, which comes off on the fingers as a dust when these insects are handled, and, if examined under a microscope, this "dust" is seen to be composed of minute scales of definite forms. Most Lepidoptera also possess a coiled "tongue" or haustellum in front of the head. Metamorphosis is complete and the larvae are caterpillars which carry up to a maximum of eight pairs of feet; the pupae generally have their appendages more or less glued down to the body and are said to be obtected and are usually enclosed in a silken cocoon or in an earthen cell. At least 8o,000 species have been described and of these over 2,000 inhabit the British isles and more than 9,000 occur in America, north of Mexico.
The Head.—The head is small and sub-globular in shape with the compound eyes exceedingly well developed and a pair of simple eyes or ocelli often present on the vertex (fig. 3). The antennae are many-jointed : in numerous moths they are thread like, in others they bear comb-like processes and are said to be pectinate (fig. 1), a development that is most pronounced in the males; among butterflies the antennae terminate in a club or knob. The mouth-parts (fig. 2) are nearly always adapted for sucking, with the mandibles reduced to vestiges or entirely want ing. The maxillae have their two galeae greatly elongated and interlocked to form a sucking tube, through which the food is imbibed ; it is coiled up in a watch-spring-like manner when at rest, but extended straight out when sucking nectar from flowers.
Maxillary palpi are generally re duced or wanting and the labium is represented by a small plate generally bearing prominent three-jointed palpi. In some Le pidoptera the mouth-parts are aborted and no food is taken in the adult stage, while at the other extreme in certain hawk-moths the haustellum is over 6in. long
and adapted for probing the deeply-seated nectaries of tubular flowers. In a few cases the haus tellum bears toothed spines at its apex, and those moths which possess this feature are able to lacerate the rind of fruits and suck the juices within.