The fore wings are grey, and marked with longitudinal dark lines, the principal of which is a line from the middle of the base to about the centre of the wing. The wing rays are also darker than the ground colour. The hind wings are greyish white or brownish grey.
The caterpillar is very dark brown, with orange spots on the back and along the spiracles. It feeds on sow-thistles (Sonchus oleraceus, S. palustris, and S. arvensis) and sleepwort (Lactuca virosa) at night from July to September, and hides during the daytime among the leaves that lie close against the ground. When disturbed it does not roll into a ring or feign death like many others of its kind, but wriggles about most vigorously as if to repel its foe.
Family—Gonopteridæ
The Herald Moth (Gonoptera Libatrix)
The above-mentioned family is so called on account of the angular margins of the wings, especially the fore pair. It contains only one British species, the Herald ([Plate XII], fig. 1), a moth that is common everywhere in August and September. It hybernates in the perfect state, and the hybernated specimens may be seen in the spring time, from March up to the end of May or the beginning of June.
Its fore wings are reddish grey, thickly spotted and streaked with brown. Transverse whitish lines divide the base into three parts of nearly equal widths. The basal and central divisions are tinged with orange; and there is a small white spot in the base close to the thorax, also another near the centre of the wing. The hind wings are brownish grey.
The caterpillar is green and velvety, with a whitish stripe on the side, and yellow spiracles. It feeds on willow (Salix alba) and sallow (Salix caprea); and when full grown, about the end of June, it spins a white silken cocoon between leaves of its tree, and changes to a very dark chrysalis.
Family—Plusiidæ
The most peculiar feature of the moths of this family is the tufts of hair that stand up perpendicularly on the top of the thorax. The abdomen also is crested, and the fore wings of several species have smooth patches that display a brilliant metallic lustre.