The Lesser Cream Wave (Acidalia (Leptomeris) immutata).
White, more or less tinged with ochreous or ochreous grey in the male, is the general colour of this moth; the wings are crossed by several ochreous lines, the third line of the fore wings and the second line of the hind wings rather wavy. All the wings with central black dots, most distinct on the hind pair, occasionally absent from fore wings. (Plate [49], Figs. 3 ♂, 4 ♀.)
The long caterpillar is pale greyish-brown, with three dusky lines on the back; the black spiracles are set in a pale stripe, and below this is a dusky line; head small and round (Barrett). August to May. The natural food appears to be Valeriana officinalis, and Spiræa, but it has been reared from the egg on groundsel, knotgrass, etc., also hawthorn, and moths obtained the same year, about September.
In the open the moth is to be found in fens, bogs, and marshy places in fields and woods, during June and July. It is not uncommon, in suitable spots, in most of the southern and eastern counties of England. In the west, including Wales, and through the Midlands, it is local to Yorkshire, but is widely distributed in the south of the latter county; it occurs, rarely, in Durham. In Scotland it has only been definitely noted from Arran. Widely distributed, and common, in many parts of Ireland.
Abroad, the range extends to Amurland.
The Mullein Wave (Acidalia (Leptomeris) marginepunctata).
This species exhibits more variation than is usual in this group. Typically, the moth is greyish white, but in some specimens the grey is most in evidence, and in others the white. A practically black form, with white fringes, has been noted from North Cornwall, and at Eastbourne and Portland many of the specimens have a clear, bone-coloured ground, with fine but very distinct cross-markings; these seem to be referable to ab. pastoraria, Joannis. The cross lines in both dark and light forms are sometimes very indistinct, but occasionally the first and second of the fore wings are united, and so form an irregular dusky band; the greyish clouding on the outer marginal area is also variable. Three
specimens are shown on Plate [49]; two from Eastbourne, Figs. 5 ♀, 6 ♂, and one from Essex, Fig. 7 ♀.
The long caterpillar is very pale slaty-olive, with three paler lines along the back, the central one edged on each side with olive, darkest on the last three rings; spiracles black, and under surface of the body pale slate blue (adapted from Porritt). It feeds on various low-growing plants, among which, yarrow, mugwort, chickweed, cinquefoil, and knotgrass have been mentioned; also, it is said, on sallow. There are certainly two broods in the south, one feeding up in the summer, and the other hatching in September, and after hibernation attaining full growth in May or June. Moths of the first generation are on the wing in June and July, and of the second in August and September. Although sometimes found inland, the species is more especially attached to the coast, and is found in nearly all the seaboard counties of England, Wales, and Ireland. In Scotland, it occurs in Wigtownshire, and very dark specimens have been obtained on rocks in dry pastures at Ardrossan; June to end of July.