The typical form of this species has the fore wings of a pale slaty grey colour; this, however, does not seem to occur in Britain. Our form, var. suffusa, Tutt (shown on Plate [13], Figs. 1 and 2), is much darker grey with blackish mottling, a yellowish mark at the base and a reddish cloud in the reniform stigma; the outer area is more or less tinged with violet, and this tint sometimes spreads over the whole of the fore wings;
the inner margin is tinged with reddish orange at the base, or along the basal half, and there are some clouds of the same colour on the black submarginal line. This is conformis of British authors.
The caterpillar (drawn from a skin, Plate [8], Fig. 1) is olive brown, tinged with green above, and paler brown, tinged with pink beneath; the dots are yellowish in black circles, and there is a dark olive-brown mark on ring 1; there are three yellow lines along the back, the central one interrupted by darker brown freckles, clustered so as to form a series of diamond-shaped patches, and the others are edged above with dark olive. It feeds on alder, from April to June.
The moth is out in September and October, and, after hibernation, in March and April. Ivy bloom and sugar attract it in the autumn, and it has been taken at sallow catkins as well as at sugar in the spring.
Since 1861, when its occurrence in Wales was first announced, it has been found more or less regularly in Glamorganshire, South Wales, or the adjoining English county of Monmouth. The latest record is that by Mr. P. J. Barraud, who took a male specimen at sallow bloom in the Wye Valley on March 31, 1907. The capture of a specimen at sugar, near Brighton, September 13, 1898, has been reported. One specimen has been recorded from Yorks., another from Westmoreland; and in 1902, two from near Lancaster. Wales, however, appears to be the home of this species in the British Isles.
The Nonconformist (Graptolitha (Xylina) lamda).
The example of this species shown on Plate [13], Fig. 3, is of the typical form, and hails from the Continent. Of the six specimens observed in England the majority have been recorded as zinckenii, Treitschke, a form having the fore wings more variegated with white. Another form, ab. somniculosa, Hering,
has most of the typical markings, especially on the outer area, absent.
The earliest occurrence of this species in Britain appears to have been that of a specimen on the trunk of a poplar tree in the northern environs of London, October, 1865. Then on September 30, 1866, one was detected on the bole of a willow tree in a locality not indicated more definitely than "near New Cross"; another specimen was taken in the same year in the Guildford district, at sugar. On October 3, 1870, a fourth was found on the reverse side of a tree that had been sugared, at Dartford, Kent; and a specimen, labelled Erith, September, 1875, was in the collection of the late Mr. Bond. Lastly, a specimen came to sugar at Copdock, Ipswich, in late September, 1895.
The range of this species abroad extends through Scandinavia, Belgium, North Germany, and North Russia, to East Siberia, and Amurland. It is found in North America, where it is known as thaxteri, Grote.