The caterpillar (Plate [145], Fig. 5) is whitish, inclining to green, yellow, or pinkish, on the back, and the sides are pinkish brown; the hairy warts are brown or pinkish brown, and the small head is glossy black. It feeds on sorrel (Rumex acetosa), and it attains full growth, after hibernation, about the end of April. On leaving the egg-shell in the summer, the young caterpillar bores into a leaf, and eats the tissue between the upper and lower skins; later on it attacks the foliage from the underside, but leaves the upper skin intact; or the process may be reversed, and the under skin left.
The moth is on the wing in June, sometimes late May. It occurs, locally, in meadows, frequently damp ones, where there is plenty of ragged-robin (Lychnis flos-cuculi), the blossoms of which plant it seems to prefer to all others.
Widely distributed over England, but in Wales only recorded from Capel Curig and Barmouth, in the north of that country (1900). In Scotland its range extends to Moray; and in Ireland it is found in counties Wicklow, Cork, Clare, Westmeath, Monaghan, Sligo, and Galway.
Cistus Forester (Ino (Adscita) geryon).
This species is much smaller than the last; the fore wings, the outer margins of which are somewhat rounded, are bronze green, but, in the male, rather dull in tint, sometimes tinged with golden towards the base. The antennae are more stumpy than those of statices, but in other respects they are similar in appearance. The female is not much smaller than the male. (Plate [147], Figs. 10 ♂, 11 ♀.)
The caterpillar is yellowish white, with bristle-bearing warts of pretty much the same colour; three lines on the back, the central one whitish, edged on each side with purplish, the others waved and of a claret colour; a reddish-brown stripe low down
along the sides; head and plate on first ring of the body black, the latter edged in front with yellowish. It feeds on rock rose (Helianthemum chamæcistus). At first it attacks the leaf from the upper side, and partly burrows therein; when older it clears away patches from the under surface, leaving the upper skin of the leaf more or less transparent; as it approaches full growth it likes to take its meals in the sunshine, and then eats the top skin as well as other parts of the leaf, and also tender shoots: July to May. The moth is out in June and July, as a rule, but is sometimes observed in May. Its haunts are on warm slopes of chalk downs and limestone hills, where it flies in the sunshine.
This species was first noted as British in March, 1860, when specimens from Worcestershire were recorded as Procris tenuicornis. It seems, however, to have been considered doubtfully distinct from statices until 1863, when the caterpillar was found, and the occurrence of the species in several other English counties recorded. At the present time I. geryon is known to inhabit Sussex (Brighton and Lewes districts), Kent (Canterbury and Shorncliffe), Bucks (Aylesbury and Tring), Oxfordshire (Chinor), Gloucestershire (Cotswolds), Worcestershire (Malvern Hills), Derbyshire and North Staffordshire (Bakewell and Dovedale), Yorkshire (Richmond, Barnsley, Sheffield, etc.), and Durham (banks on the coast). In Wales, it is sometimes common on Great Orme's Head, Carnarvonshire.