Silky Wave (Acidalia (Ptychopoda) holosericata).
Somewhat similar to A. interjectaria, but tinged with pale brown, and even more glossy; the front edge of the fore wings is of the general coloration, and the only markings on the wings are darker cross lines, the third on the fore wings, and the second on the hind wings, being the most distinct. (Plate [45], Fig. 13.)
The rough and rather stumpy caterpillar tapers towards the small notched head; general colour dusky reddish-brown, a pale line along the middle of the back, finely edged with black. It feeds from August to May on rock rose (Helianthemum), eating the withered and even mouldy leaves. Will eat knotgrass, and, no doubt, dandelion also.
Here, again, we have an ancient name brought forward to supplant that which the species has borne for years, and by which it is well known to entomologists. As I am not quite certain that Hübner's (Fig. 100) dilataria does represent this species, Duponchel's name is here retained.
As a British insect, it has only been known since 1851, when the capture of a specimen in the neighbourhood of Bristol was recorded in The Zoologist. Subsequently it transpired that the scene of capture was Durdham Down, Gloucestershire, and here it has been found annually, and in some plenty, among the bushes and low vegetation covering the ground in that rugged locality. Specimens have also been noted from Berkshire (Newbury), Bucks (Chalfont St. Peter), Dorset (Halstock),
and Norfolk (Thetford). Possibly there are other localities in England, more especially in the west, where this species may be awaiting discovery.
The Satin Wave (Acidalia (Ptychopoda) subsericeata).
The wings of this species (Plate [45], Fig. 17) are glossy whitish, with a faint greyish, or sometimes yellow greyish, tinge; the cross lines are grey, oblique and straight on the fore wings, but the outer two on the hind wings are curved or bent.
Var. mancuniata, Knaggs, a local form found in Lancashire and Yorkshire, is rather more tinged with yellowish, the lines being distinct, and some more or less distinct dusky dots on the outer margin of the fore wings.
A blackish form, with white fringes, has been recorded from North Cornwall, where the species, in its usual form, has been noted as abundant.