The eggs are greenish white, and the full-grown caterpillar is purplish brown on the back merging into violet on the sides; there is a broad yellow stripe along the spiracle area; the head is violet, faintly marked with black. A noticeable feature of this caterpillar is its varnished appearance. It feeds on birch in June and July, and sometimes in September and October. The early stages are figured on Plate [29], Figs. 3, 3a, and 3b.
The species has a somewhat similar distribution to that mentioned for the preceding, but it seems to be commoner in the North of England and in Scotland than elsewhere in the British Isles.
The Pebble Prominent (Notodonta ziczac).
This moth varies in the colour of the fore wings from pale ochreous brown to a darker brown tinged with reddish; the usual pale greyish patch in the middle of the costal area is
sometimes obliterated by a suffusion of the darker colour; the dark-brown first and second lines are often only visible towards the front edge of the wings; a blackish lunule or crescent forms, in conjunction with the strongly curved outer line, the outline of the characteristic pebble-like mark on the apical area of the wings; a pale saw-edged line, which is inwardly shaded with dusky and intersected by black streaks on the veins, traverses the pebble mark, but in the lighter coloured specimens this line is not traceable. The female has browner hind wings than the male. The moth is depicted on Plate [31], Fig. 2; and the early stages on Plate [30], Figs. 1, 1a, and 1b.
The caterpillar, when full grown, is pale ochreous grey, sometimes tinged with pink or purplish brown, or with yellowish, and especially on the hind rings; a yellow stripe along the back is edged here and there with brownish; the diffuse dusky line along the area of the black margined spiracles is edged with yellowish. It is occasionally found on poplar, but sallows and willow are the more usual food plants, and it feeds upon these in June and July and again in August and September. The reddish brown chrysalis is enclosed in an earthen cocoon just under the surface of the ground at the roots of tree or bush upon which the caterpillar fed. The moth emerges in May and June from chrysalides of the previous year, and in August as a second generation. Three broods in the year have been obtained in confinement, but this is probably exceptional.
Widely distributed throughout the British Isles, but seems to have a preference for fens and marshy ground. It occurs all over Central and Northern Europe, its range extends through France to Spain, Italy, and Corsica, and it has been recorded from Armenia and Amurland.
The Iron Prominent (Notodonta dromedarius).
The specimen shown on Plate [31] is from Surrey, and represents the form most frequently obtained in the south of England. Northwards the species becomes darker in colour, and the reddish and yellow marking much reduced. The form perfusca, as figured by Stephens, has the fore wings dark purplish grey, streaked with dark brown; a pale patch at the base is russet marked, the line before the middle of the wing is russet, and a dash of the same colour lies at the lower extremity of the line beyond the middle; the hind wings are brownish grey with a broad whitish cross line. The specimen, which is of the female sex, was from Dublin, and the form was not then supposed to occur in any other part of the British Isles. It is now, however, well known in Scotland and the North of England, and also in Ireland. Some examples that I have seen from Scotland are much larger and darker than the figure referred to. In his description of this form Stephens states that the fore wings are fuscous mixed with chestnut, with darker clouds. The caterpillar, which is figured on Plate [30], is green, becoming yellowish on the back; a rather broad stripe on the back of the front rings and the markings on the humps and on other parts of the body are purplish brown. It feeds on birch, alder, and sometimes hazel, usually on the former, in June, July, and August. In some seasons, and localities, the moth appears twice in the year: the caterpillar may then be found in September and October. The chrysalis is blackish-brown and rather glossy, enclosed in a cocoon composed of silk and sand or other soil, and may be obtained by lightly digging up the earth and sods at the roots of trees.