About Orthosia opima Hübner
Technical description and variation: The wingspan of Orthosia opima Hübner measures 34–40 mm. The forewing is a dull lilac grey color, speckled with darker markings; the inner and outer lines are purplish brown. The median area is either filled with brown, or has a broad brown median shade; the submarginal line is broadly pale, with a dark line running before it, and is nearly straight; the upper stigmata are large and outlined with pale color. The hindwing is a dull brownish grey. It can be distinguished from Orthosia incerta by the straighter costa and more produced apex of the forewing. Continental forms of this moth are darker than the forms found in Britain. The most common British form is ab. grisea Tutt, which has a pale ochreous-grey ground color, with strongly marked pale edges to the stigmata and a broad submarginal line. The form brunnea Tutt has the entire forewing brownish, but the edges of the stigmata and the submarginal line remain pale. In the form unicolor Tutt, the whole forewing is brown.
