Distribution
It is found in northern and central Europe; further south and east it seems to be confined to the mountains Pyrenees, Alps, Urals.Description
The wingspan is 24–29 mm. The ground colour of the forewings is generally pale or dark grey. There are two dark stains near the apex and the costa of the forewing. The wavy crosslines delimit a darker mid field and a darker marginal field. It is very variable in colour, with the male considerably darker than the female; in some districts the sexual dimorphism is quite striking. This sex is also appreciably smaller and narrower-winged than the male and has a much stouter abdomen. - ab. ''ochroleucata'' Auriv. is unicolorous grey yellow or yellow brown without markings except the light subterminal line. - In ab. ''nigrofasciata'' Rbl. The ground colour is darkened and the median band narrow, almost black. - ab. ''nigra'' Prout has uniform blackish brown wings. In ''hethlandica'' Rbl. the male is more or less bright orange brown, the female lighter ochreous brown or fawn colour. Prout, L. B. (1912–16). Geometridae. In A. Seitz (ed.) ''The Macrolepidoptera of the World''. The Palaearctic Geometridae, 4. 479 pp. Alfred Kernen, Stuttgart. The larva is long and slender and differs so from most species of the genus ''Biology
Adults are on wing from June to August. There is one generation per year. The larvae feed on various plants, including ''Subspecies
*''Mesotype didymata didymata'' *''Mesotype didymata hethlandica'' (Shetland Isles)References
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