Grey chi

A. chi L. (33 i, 34 a). Forewing chalk white, grey-speckled; the lines double, grey; median area darker, the stigmata pale grey and conspicuous; the claviform at extremity edged with black and joined by a black dash to the inner blacker arm of outer line; submarginal line formed of whitish spots preceded by black wedge shaped marks; hindwing of male white with interrupted grey submarginal band; of female blackish grey, with darker cellspot, veins, and outer line; the females are always darker grey than the males; — olivacea Stph. (34 a) from Scotland is suffused throughout with olive grey; — subcaerulea Graes., from N. E. Amurland, is dark bluish grey in the forewing;- suitusa Robson is a dark grey form from the North of England, of which the males are equally dark with the females an extreme local development of this form from the neighbourhood of Huddersfield, Yorkshire, ab. nigrescens Tutt is nearly black; ab. langei Harrison (34 a) is like olivacea but the submarginal line is absent, and the black marks preceding it wholly or nearly obsolete. Larva green, finely dotted with yellow; dorsal and subdorsal lines whitish; spiracular line yellowish white, diffusely dark green above . ==Biology==