Generally distributed over the southern half of England; plentiful in some years in the Southern and Eastern Counties. Northwards and in Scotland it is local and less frequent. Kane states that in Ireland it is very locally abundant. The range abroad is through Central and Northern Europe to Southern Lapland, and eastward to Siberia and Amurland.
The three moths, one male and two females, shown on Plate 52, were reared from caterpillars obtained in Kent, and they { 116} represent the more or less ordinary South English forms of the species. Sometimes the ground colour of the male is more distinctly reddish, or rust tinted, and the yellowish bands narrower on all the wings. Or the bands may be much broader than in the male figured, and the widening is effected by extension in the form of rays towards the outer margins of the wings. A form that has been referred to, in error, as var. _roboris_, Shrank (= _marginata_, Tutt), has the outer margins of all the wings broadly yellow. I have not seen an English example of this form, but I have a reddish specimen in which the yellow band on the fore wings is broader than usual, and the whole of the outer third of the hind wings yellow, with a slight brownish shade on the external margin; this is _semimarginata_, Tutt, and is also identical with var. _roboris_ of other British authors. The white spot usually present on the fore wings varies somewhat in size and shape; it is often seen on the under as well as the upper surface of the wings, except in the lighter coloured forms.
Var. _callunæ_ (The Northern Eggar), is shown on Plate 54. The chief features of this form are the generally darker coloration in both sexes, the yellow patch at the base of the fore wings of the male, and the outward turn of the lower ends of the yellow bands. All these characters are subject to modification; the yellow bands may be very narrow at one extreme, or greatly widened at the other, and the hind wings may occasionally be bandless; the basal patch is often of large size, but in some examples it is entirely absent. Sometimes the bands are greenish in colour (var. _olivaceo-fasciata_, Cockerell), and more rarely, perhaps, the greenish tinge extends over the whole of the wings (ab. _olivacea_, Tutt). It should be noted here that the var. _olivaceo-fasciata_ has occurred once or twice in South England, but this phase of aberration seems to be more connected with _callunæ_ than with _quercus_.