The Imago.— When the period of pupation is ended the butterfly or moth breaks through the pupal shell and emerges a four-winged, six footed insect, known as the imago. The females of some species of moths are apterous, or pro vided with wings so poorly developed that they cannot be used in flight.
Classification.— The classification of the Lepidoptera has afforded opportunity for much divergence of opinion among naturalists, hut the division into two great suborders, the Rhopalo cera, or butterflies, and the Heterocera, or moths, is well established in usage.
The Rhopalocera contains six families: I. ("Brush-footed Butterflies'). —The front pair of legs greatly reduced in size, tarsi of the male with but one joint, of the female with five, but without claws, the pupa suspended by the cremaster. There are eight subfamilies in this group, more than 250 genera and about 5,000 species known at the present time. Among these are some of the largest and most splendidly colored butterflies, which are known, as well as some of the smallest and most obscurely colored forms. The family is repre sented in all parts of the globe.
II. Erycinidw ("Metal-marks') .— The fe male has the first pair of legs weakly, though perfectly developed. The coxa of the foreleg of the males is spined, and the tarsi are unjointed and without claws. There are over 60 genera and fully 1,000 species in this group. The but terflies composing it are generally small, but gaily and curiously colored. The metropolis of the family is found in the hot lands of the New World, though it is also represented in the Eastern Hemisphere.
III. Lycamidce ("Blues,)' "Coppers' and fore legs of the male are aborted, the tarsus having but a single joint terminated by a single claw. There are over 2,000 species known. The butterflies are gen erally small. The upper sides of the wings are prevalently some shade of blue, bronzy green or copper, though there are some species, especially in Africa, yellow, red or white.
IV. Pieridee ("Whites,' and 'Orange-tips').—The six legs are well devel oped in both sexes and the feet have two hooks or claws at the end. There are about 1,200 species known to science. The "cabbage butter and the "common sulphur)) of the clover fields are fair representatives.
V. Papilionide ( °Swallow-tai led Bu tter flieso).— The six legs are well developed. The claws are simple. About 1,000 species belong to this family, among them some of the largest and most splendid tropical insects.
VI. Hesperiida. ("Skippers))).— The six lep are perfect. The claws are short and thick The bodies are relatively robust. In flight the insects are very quick and powerful, hence the common name. The butterflies are generally small, though there are some quite large species.
There are about 13,000 species of butterflies which have been named and described. It is probable that when we shall have explored the entire earth the total number of existing species may be found to be 18,000.
The Heterocera, or moths, may be divided into about 60 families, of which 43 are repre sented in North America. The families which have the largest number of species in North America are the Noctuidce, or 'owlet-moths," the Geometrida", or °measuring-worm moths,)) the Saturniidie, or ewild silk-moths,° the Arc tiidce, or "tiger-moths," the Sphingidce, or lhawk-moths," the Tortricidcs, or "leaf-rollers,Th and the Pyralichr. More than 7,000 species of moths are known to occur in the United States and Canada, and probably more than 100,000 species at present exist upon the globe.
The most important of all the Lepidoptera from a commercial standpoint is the silk-moth (Bombyx mori), which was introduced into Europe from China by way of India, and at an early date was brought to the New World.
Beutenmiiller, of Sesiida of North America' (Memoirs American Museum of Natural History) ; Dick inson, 'Moths and Butterflies' (Boston 1905); Dyar, 'A List of North American Lepidoptera' (Bulletin, United States Natural Museum, No. 52) ; Edwards, 'The Butterflies of North Amer ica' ; Felt, E. P., 'Gypsy and Brown Tail Moth' (Bulletin, New York State Museum, No. 103, Albany 1906) ; Hampson, 'Catalogue of the Lepidoptera Phalanx in the Collection of the British Museum' ; Holland, 'The Butterfly Book' (1898; 2d ed., 1904) ; id., 'The Moth Book' (1905) ; Packard, 'Monograph of Geo metridz' (Hayden's Survey, Vol. X); id., 'Monograph of Notodontidz' (Memoirs Na tional Academy of Science, Vol. VII) ; Roths child and Jordan, 'A Revision of the Lepidop terous Family Sphingidx); Scudder, 'Butterflies of New England' (1889) ; Smith, 'Catalogue of the NoctuidaP (Bulletin, United States Natural Museum, No. 44) ; Transactions of the Amer ican Entomological Society (published quarterly since 1867) ; Entomological News (published monthly since 1890) ; Psyche (published bi monthly since 1877).