The caterpillar (Plate [47], Fig. 2; from coloured drawing by Mr. Sich) is much wrinkled, rather thickened behind, and tapers gradually towards the small, black-flecked head; the general colour is brownish, merging into ochreous on the hinder rings; a darker brown shade along the back, interrupted on the middle rings by V-shaped marks, encloses a slender whitish line, and there is a whitish spot on ring eight; a wavy pale ochreous line low down along the sides. (Adapted from Fenn.) It feeds on dandelion, dock, primrose, bedstraw, knotgrass, and many other low-growing plants; after hibernation, from April to May, it will thrive on the young growth of sallow, birch, hawthorn, etc. It will sometimes feed up and reach the moth state in August or September.
The moth flies in June and July, and is generally distributed; but in Scotland does not seem to have been observed north of Moray.
Small Fan-footed Wave (Acidalia (Ptychopoda) bisetata).
One form (Plate [46], Fig. 10) has whitish wings, with a deep, dark-grey border on the outer area of all the wings; this border is traversed by a whitish, wavy line (ab. fimbriolata, Stephens). Another form (Plate [46], Fig. 7) is more or less typical, and in this it will be noted that the marginal borders are much paler, and are broken up into bandlets. Between these two forms there are modifications, and sometimes a greyish shade spreads over all the wings.
The caterpillar is long and slender, with a somewhat flattened appearance, and gradually tapered towards the notched head; the general colour of the roughened body is greyish brown, the middle ring divisions, and V-shaped marks on the back, are blackish or dark brown; there is also a double dark-brown line along the back, not always distinct. It feeds, from August to May, on a variety of low-growing plants, and is partial to withered leaves, especially those of bramble and dandelion. The moth is out in June and July, and is often common, and pretty generally distributed throughout our islands, except that it seems not to have been noted north of Moray, in Scotland.
Abroad, the range extends to East Siberia and Amurland.
The Single Dotted Wave (Acidalia (Ptychopoda) dimidiata).
The most noticeable feature in this whity brown moth (Plate [47], Figs. 9 and 12), sometimes known as scutulata, are the larger dots at the costal end of the dotted cross lines, and the blackish or dark-brown chain-like mark on the lower part of the outer marginal area of the fore wings; the latter is sometimes obscured in a cloud of its own colour.