Richard South, The Moths of the British Isles…
“ In the spring, when it awakens, the green colour increases in extent as the buds open and the leaves unfold; when they are fully expanded, the caterpillar sits among the foliage towards the tip of a twig, and is then almost entirely green, the reddish brown only showing on the head, slightly on the warts, and more distinctly on the hinder parts which are in touch with the twig. The chrysalis, enclosed in a flimsy silken web among the dead leaves, usually on the ground, is of a delicate green colour, dotted with buff on the back, and shaded with buff on the wing cases. ”
