[...] in Durham it is widespread through out the county, though nowhere to be found in great numbers. We have the distinct impression that it is becoming less plentiful (probably as the result of improved methods of pest control) and certainly can no longer be regarded as 'an abundant species everywhere. - .' as it was in Robson's time. With us, the autumn generation (late August -mid-October) is scarcer than the early emergence (mid-June - mid-July), and it may be that spells of unseasonably cold weather in late spring during recent years are also taking their toll. Dark specimens in which the forewing markings are vestigial (ab. subatnatus Haworth) occur commonly with the type.