Some thirteen or fourteen species occurring in Europe are referred by Staudinger to this family. Only five of these occur in the British Isles. The moths are of rather small size, less, in fact, than some of the so-called "Micros," among which they have been placed. Probably they may, for this reason, be overlooked. They mostly sit head downwards on the trunks, branches, or leaves of trees, sometimes on palings, but the rarer ones hide themselves among the thick, low herbage. The time of flight is after dark, and the moths occasionally visit the sugar patch. The caterpillar has only eight false legs (prolegs), the first pair being the absent ones; the body is clothed with tufts of hair, the hairs of the front and rear tufts longer than the others. When full grown it spins a more or less spindle-shaped, toughish cocoon of silk mixed with the larval hairs, which is usually coated with particles scraped from the surface of twig or stem upon which it is spun up.
The fore wings are whitish or greyish, with a dark, almost black, patch at the base; this patch is marked with whitish, and is limited by the first cross line, which is black and curved; the second line, also black, is wavy and curved inwards towards the front margin; between these lines is a dusky central shade, commencing in a blackish spot on the front margin, and sometimes forming an inward border to the second line; a raised tuft of white, grey-capped scales on the basal patch, and two other tufts beyond it and in a line with the front margin; hind wings dark grey, paler towards the base (Plate 73).
The caterpillar is reddish brown, clothed with short greyish hairs; the spots and central line on the back are whitish. It hatches from the egg early in August, and after feeding for a while, retires to winter quarters, selecting some sheltered cranny, such as a chink in the tree bark, where it spins over itself a few strands of silk. Feeding is resumed in May and June, after hibernation, usually on the upperside of leaves of sloe and whitethorn, and also of fruit trees, such as apple and plum, and sometimes pear (Plate 72).
The moth is out in June and July. It flies at dusk.
Widely distributed and generally common in the south of England; somewhat rare in Scotland—perhaps overlooked. It has been reported from Ireland, but is not mentioned by Kane in his catalogue of Irish Lepidoptera.
Fore wings greyish white, freckled and dusted with grey brown at the base and on the front and outer margins; two black wavy and toothed cross lines; between the base of the wing and the second line are three raised tufts of grey brown tipped whitish scales: hind wings dark grey, paler towards the base (Plate 73).
The caterpillar feeds, probably after hibernation, from April to June, on the undersides of oak leaves. It is pale ochreous in colour, with pale reddish brown warts and star-like tufts of hair; a blackish bar on the back of ring six; head blackish.
The moth emerges from the chrysalis in July. It occurs in oak woods in Kent, Surrey, Sussex, Hants, Somerset and Gloucestershire; also in Berks, Norfolk, Suffolk, and Essex, but it is very local and seems to be restricted to a more or less limited area in all its known haunts, among which the most favoured are perhaps the New Forest in Hampshire and Abbots Wood in Sussex. In some years it may be fairly common, or even plentiful, and then becomes quite scarce during several seasons in the same place.
Very similar to the last species, but whiter; the first line is curved towards the second tuft of raised scales, thence gently curved to the inner margin, above which there is a slight inward angle or elbow; the second line is less wavy; hind wings whitish grey with a black central dot, and in the male whiter along the inner area. The head and palpi of this species are white, but strigula has a greyish white head and dark palpi. Again, the antennæ in the male of the present species are ciliated, but in male strigula they are bipectinated (Plate 73).
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.