Page:EB1911 - Volume 16.djvu/493

Rh exceptional condition—and are protected by a cocoon of silk mixed with some of the larval hairs, while the female sheds some hairs from her own abdomen to cover the eggs. The family is widely distributed, its headquarters being the eastern tropics. To that part of the world is restricted the allied family of the Hypsidae, distinguished from the “tussocks” by the slender upturned terminal segment of the labial palps and by the development of the maxillae.

The Noctuidae are the largest and most dominant family of the Lepidoptera, comprising some 10,000 known species. They are mostly moths of dull coloration, flying at dusk or by night. The maxillae are well developed, the hindwing has a frenulum, and its sub-costal nervure touches the radial near the base. The larvae of the Noctuidae (fig. 34, c) are rarely hairy and the pupa (fig. 34, d) usually rests in an earthen cell, being often the wintering stage for the species; sometimes the pupa is enclosed in a loose cocoon of silk and leaves. In some Noctuidae (fig. 32) the hindwings are brightly coloured, but these are concealed beneath the dull, inconspicuous forewings when the insect rests (fig. 34, f). Nearly allied to the Noctuidae, but very different in appearance, are the gaily-coloured Agaristidae, a family of day-flying moths (figs. 35, 36), confined to the warmer regions of the globe and distinguished by their thickened feelers, those of the Noctuids being thread-like or slightly pectinate.

The Arctiidae (tiger moths, footmen, &c.) are allied to the Noctuidae, but their wing-neuration is more specialized, the sub-costal nervure of the hindwing being confluent with the radial for the basal part of its course. These moths (fig. 37) have gaily coloured wings, and the caterpillars are often densely covered with long smooth hairs. The pupae are enclosed in silken cocoons (fig. 38). The highest specialization of structure in this group of the Lepidoptera is reached by the Syntomidae, a family nearly allied to the Arctiidae, but with the sub-costal nervure in the hindwing absent. The Syntomidae have elongate narrow forewings and short hindwings, usually dark in colour with clear spots and dashes destitute of scales (fig. 40). The body, on the other hand, is often brilliantly adorned. The family, abundant in the tropics of the Old World, has only two European species.

This group includes a series of families which agree with the Noctuides in most points, but are distinguished by the origin of the second median nervure of the forewing close to the first, or from the discocellular nervure midway between the first and third medians (see fig. 5). These neurational characters may appear somewhat insignificant, but such slight though constant distinctions in structures of no adaptational value may be safely regarded as truly significant of relationship. Several of the families in this group have lost the frenulum. In larval and pupal characters the Sphingides generally resemble the Noctuides, but in some families there is a reduction in the number of the larval prolegs. The egg is spherical or flat, upright only in the Notodontidae.

The Notodontidae are stout, hairy moths (figs. 5, 41, 42 a) with maxillae and frenulum developed. In the larva the prolegs on the hindmost segment are sometimes modified into pointed outgrowths which are carried erect when the caterpillar moves about. From these structures whip-like, coloured processes are protruded by the caterpillar (fig. 42 b) of the puss moth (Cerura) when alarmed; these processes are believed to help in “terrifying” the caterpillar’s enemies. Allied to the Notodontidae are the Cymatophoridae—a family of moths agreeing with the Noctuidae in appearance and habits—and the large and important family of the Geometridae. 