About seventy-two species, referred to this family, are known to occur in various parts of the Palæarctic region; ten of these are found in our islands. The Black V-moth (Leucoma v-nigrum or Arctornis l-album) has been reported as British, but if the few examples that have been recorded were natives, the species has long since disappeared from this country.
Some of the caterpillars, as, for example, those of the Brown and Yellow-tails, are not altogether pleasant to handle, as the hairs with which they are covered have a disagreeable trick of transferring themselves to our hands, whence they find their way to our face, and when there are apt to set up most unpleasant irritation and swelling of the parts affected. These urticating hairs are more troublesome when received from the caterpillar or cocoon, but those from the moth itself communicate a very respectable simulation of the skin trouble known to the doctor as Urticaria.
The Scarce Vapourer (Orgyia gonostigma).
The male of this species, and also of the next, flies in the sunshine, but the female of each is wingless, or nearly so, and has to remain at home on the cocoon from which she emerged. Here she lays a large number of eggs, from four to five hundred, upon the exterior. The eggs of this species are whitish and rather glossy when first laid; the top is sunken. Apart from
the deeper brown colour of the fore wings and the blacker hind wings, the male of this species has a white mark near the tip of each fore wing, and this character will distinguish it from the same sex of the Common Vapourer.
The caterpillar is blackish with star-like tufts of hair, white on the back and greyish on the sides; on rings four to seven are brushes of brown hairs; a pencil of black hair on side of the first ring pointing forward, and a thicker one on the back of ring eleven directed backward; the interrupted stripes along the back and sides are reddish orange, approaching vermilion; those along the back are united in front of the pencil on ring eleven, and those of the sides unite behind the pencil. Head glossy, black. The foliage of sallow, willow, and oak, is perhaps the more usual food, but it has been known to eat beech, elm, hawthorn, sloe, and nut, and has been found on meadow-sweet. The chrysalis is brown, inclining to yellowish between the rings, and the back is hairy; enclosed in a cocoon spun up among leaves or in any suitable cranny. The male and female moths are figured on Plate [40] (Fig. 3, 5), and the caterpillar and chrysalis on Plate [41].
The moths emerge in June, and from their eggs caterpillars result in July. These, feeding up quickly, attain the perfect state in late July or early August. Caterpillars from this second generation usually go into hibernation when quite small, and feed up in the following April and May; in confinement they may, however, get through their metamorphosis and reach the moth state in September or October. Sometimes it happens that a part of the summer brood of caterpillars will feed up straight away and produce moths in August; others, feeding and growing more slowly, assume the winged state in November; whilst a third portion will remain small and go into hibernation.
This very local species used to be obtained in the Wimbledon district, but it has not been seen there for some years past.
Other localities for it are the Norfolk and Cambridge fens, Bewdley Forest in Shropshire, and Wyre Forest, Worcestershire; it is also found in some parts of Devonshire, Suffolk, Essex, and Yorks. Its range abroad extends through Northern and Central Europe, southward to North Spain, Piedmont, and Corsica, and eastward to Amurland, Corea, and Japan.