The Nymphalidae (figs. 29, 3o) are the largest family of butter flies, and number over 5,000 species, which have the fore legs in both sexes reduced and useless for walking. Among the various subfamilies, the Nymphalinae include the peacock, tortoiseshells, admirals, fritillaries and emperors; as a rule they have spiny caterpillars (fig. 34) and the pupae hang head downwards, only supported by a cremaster (fig. 38). The Satyrinae include the heaths, graylings, meadow browns ; they are mostly sombre coloured and their larvae are smooth, feeding usually upon grasses. The Danainae are only numerous in warm countries, but one of the best known species is the monarch (Danais archippus) of North America. Several of the other subfamilies are mainly found in South America, including the splendid metallic blue Morphinae.
The Pieridae include the whites, yellows and orange tips; the fore legs are fully developed in both sexes and these insects differ from the Papilionidae in having two anal veins to the hind wings. The cabbage white (Pieris rapae), common in many parts of the world, is one of the few injurious butterflies, its larvae being destructive to various Brassica vegetables. The larvae in this family are hairy and the pupae have a single "horn" to the head and are suspended upright by a girdle of silk and a cremaster.
The Lycaenidae comprise the blues, coppers and hair-streaks, which have the fore legs normal in the female but the tarsi are shortened in the male, with one or both the claws absent ; the antennae are nearly always ringed with white and a white rim encircles each eye. They are mostly rather small butterflies, often with metallic colours above and spotted beneath. Their larvae are very short and almost slug-like and the pupae are devoid of spiny processes. The Nemeobiidae, or Lemoniidae, are closely related to the Lycaenidae and have the fore legs in the male use less for walking, but they are normally developed in the female. The family is essentially a South American one : only a few spe cies occur in the United States, while the Duke of Burgundy fritillary (Nemeobius lucina) is the sole European representative.
The eggs of Lepidoptera are generally of one of two types. They may be ovoid or flattened with the long axis hori zontal; or upright, spherical, or hemispherical with the axes either equal or the vertical axis longest. Both types may have the shell or chorion sculptured in various ways, and in the upright eggs of many butterflies the shell exhibits a beautiful cell-like structure divided by longitudinal ribs (fig. 31). The number of eggs laid is variable and a single female may deposit up to a thousand or more. Some of the swift moths and the antler moth (Charaeas
graminis) merely drop their eggs at random among the herbage upon which the future caterpillars feed. The lackey moth (Mala cosoma neustria) lays its eggs in necklace-like rings around twigs, while the garden white butterflies (Pieris) place them singly or in small groups on the undersides of leaves, and the brown tail (Euproctis chrysorrhaea) lays them in masses covered with hair derived from the anal tuft at the extremity of the body.
The larvae are known as caterpillars, which are characterized by the presence of three pairs of jointed, clawed legs on the thorax and a variable number of abdominal feet, which are short, fleshy outgrowths provided with a series of hooks or crochets on their grasping surface. These abdominal feet consist typically of five pairs, but in the geometer (fig. 23) or looper caterpillars they are only present on the 6th and loth segments. The head in caterpillars is a firmly chitinized capsule which carries six simple eyes on either side and a pair of very short antennae. The mandibles are large and strong, while the maxillae are small and inconspicuous; the labium bears a median tube or spinneret which receives the ducts of the spinning glands (fig. 32). The latter are the modified salivary glands and they produce the silk used in forming the cocoon ; in many cases these glands are very long and, in the silkworm about five times as long as the whole caterpillar. Along the sides of the body nine pairs of spiracles are found and they appear as small dots, often easily seen (fig. 24). Caterpillars are armed or protected in various ways either in virtue of their structure or of their behaviour. Some, such as those of tiger moths, are densely hairy, and in the vapourer moths (Orgyia) these hairs are grouped into conspicuous tufts and brushes (fig. 33). Certain caterpillars are efficiently pro tected by so-called urticating hairs which are very fragile and bristle with needle-like lateral points. Whether their irritating properties are due to mechanical action alone or to a poisonous secretion is uncertain, but most people who have handled hairy caterpillars of various types have experienced the effects of such hairs on the skin. In North America and also in the tropics there are caterpillars armed with true poison spines, which are tubes fed with the secretion of special glands in the skin. Such spines are capable of inflicting nasty "stings" and evidently secure for their possessors considerable immunity from attack.