The caterpillar, which feeds in July and August on the leaves of oak, beech, sloe, and apple, etc., is reddish, inclining to yellow on the back, which is traversed by black lines, the central double and interrupted on rings seven to nine by rusty V-shaped marks.
The moth flies in May and June.
This species appears to have a wider distribution than either of the others. It is the only one known with certainty to occur in Ireland, and it is widely spread in that country. In Scotland it is found in Perthshire and Ayrshire, and probably is present in other parts. In England it is obtained in most counties, except perhaps the northern, although it has been recorded from various parts of Yorkshire.
Kent Black Arches (Nola albula).
Fore wings white, largely light brown between the obscure cross lines; outer marginal area clouded, and front margin dotted with light brown; three tufts of raised scales placed as in previous species; hind wings of the male, greyish white, browner on the outer margin; of female, brownish grey. Varies in the amount of light brown, and sometimes this is much reduced; more rarely it disappears entirely (Plate [73]).
The caterpillar varies in colour from ochreous with pink tinge to bone white; the warts are set with pale hairs and those along the back and at each extremity are longest; a double greyish line along the middle of the back, and a series of black marks on each side; these marks unite across the back on rings six and ten. After hibernation, it feeds in Spring until June, on the young growth of bramble, raspberry, strawberry, and cinquefoil (Potentilla reptans), and is stated to also eat hemp agrimony (Eupatorium cannabinum). The brownish cocoon is constructed on a stem of grass and in appearance looks not unlike a swelling of the stem.
This species was first observed in England in the year 1859, when four specimens were taken in July at Chattenden Roughs, a large hilly wood in North-east Kent. It still occurs, no doubt, in the Kentish locality referred to, but is now very scarce there compared with what it must have been some twenty-five years ago. Barrett notes a specimen from the Isle of Wight. Mr. G. T. Porritt states that he has seen one of two examples captured in South Devon in 1901; and another, a male, has been recorded as taken at light in a house near Weymouth, Dorset, in August, 1904, and from Lewes in 1906.
At the time the first specimens were met with in England the species seems to have been rare, or little known on the Continent. Since then knowledge of its distribution has vastly increased, and it has now been found not only in many parts of Central Europe, but also in Finland, Italy, Dalmatia; Asia Minor, Persia, and extending into Amurland and Japan.