[...] The first notes of the species in any strength came in 1934 when J. B. Nicholson found an imago in July near Darlington, and a larva on a garden lawn a month later (Vasc. 20, 153): C. W. Murray had a moth in his greenhouse, also in Darlington, in the same year (Vasc. 21, 114). Then in 1935 J. E. Nowers reported large numbers of larvae (c. 20) in and around Darlington in August and September (Vasc. 21, 153). This was followed by a quite rapid spread throughout [...] spreading westwards to Hamsterley village [...] in 1943 [...] it was spreading over most of the lowland areas of Durham [...] It has never done so well in the west, however, although it has been seen in Teesdale at Eggleston (TCD) [...] but not in the Hamsterley Forest trap in recent times [...]. The rapid spread in the 1940's paralleled the extension of range of the Rose-bay Willowherb, the principal foodplant. Initially this became established along railway embankments where the normally wind-dispersed seed is believed to have been swept along on the slipstream of passing trains. The plant is a lover of dry slopes [...] especially where there has been disturbance of surface vegetation by public works or grass fires, creating open spaces for colonisation, and has now reached moorland verge habitats. The moth flies from mid-June to mid-July, and a second brood has been reared in captivity.