The caterpillar is greenish, light olive green, or dark olive green above, and yellowish beneath; a line along the middle of the back is paler, and on each side there is a row of black spots and finely black-edged white dots; a line above the brownish outlined spiracles is yellowish: the head is yellow brown with blackish jaws and black mark on each cheek. It feeds in June and July on birch, preferring the foliage of bushes. During the daytime it resides in a leaf neatly folded in half; when quite young, the caterpillar then being blackish, a small leaf or just the turned-over edge of a large one answers its purpose. The chrysalis is reddish, enclosed in a flimsy cocoon among leaves, moss, or roots of grass, etc., sometimes just under the surface of the soil. The early stages are figured on Plate 38, Figs. 2-2c. The moth emerges in March or April of the year following pupation, as a rule, but it may remain in the chrysalis for two winters. It is often obtained in birch woods, or wherever there {93} is a good growth of birch, by jarring the twigs and branches of birch upon which it rests during the day, or it may be found by searching the low bushes and underwood. Soon after dusk it is on the wing, and will then visit sugar and sallow bloom. Generally distributed throughout Great Britain. In Ireland it appears to be very rare. Its range abroad, in the typical form, extends over Northern and Central Europe to North Italy and to South-east Russia. THE FROSTED GREEN (_Polyploca ridens_). This moth (Plate 39, Figs. 9, 10) is also on the wing early in the year, but although it is sometimes found on tree trunks in April or perhaps as late as the first week in May, it seems to be rarely obtained otherwise in the perfect state. It does not "come to sugar" often, if at all, and so far as is known, does not visit any of the usual natural attractions. The ground colour of the fore wings varies from whitish to green, but in some specimens the general hue is olive or blackish green, and the markings then appear to be wavy whitish lines crossing the wings, one near the base, and the other before the outer margin. The caterpillar (Plate 38, Fig. 1) is yellow above and rather greenish beneath; a greenish grey double stripe along the back is interrupted at the ring divisions; there are also white dots with black or blackish edges on the back and the sides; a yellow line along the spiracle area is shaded above and below with greenish grey; the head, which is notched on the crown, is yellowish, with a black mark on each cheek. It feeds, at night, on oak, from May to July; hiding by day on the underside of a leaf, a portion of which is folded over and secured with silk, to form a suitable retreat. These caterpillars respond more readily to the persuasive beating-stick than others of the group.