About Apamea zeta (Treitschke, 1825)
Technical description and variation of Apamea zeta (originally referenced as C. zeta Tr. (41 e)). The forewing is dull grey-green, covered in hoary grey scales. The inner and outer lines are black, conversely edged with hoary grey, and are lunulate-dentate; the outer line is sinuate, and not indented below the middle. The stigmata are grey and edged with black; the two upper stigmata are separated by a clearly marked blackish median shade. The submarginal line is pale, often broken up, indented on the folds, and preceded by black wedge-shaped marks. The hindwing is fuscous, and paler toward the base. The entire forewing has a mealy appearance; in paler specimens, the markings are often much obscured.
The aberrations and forms of this species are as follows: ab. pernix Hbn.-C. (= clandestina Bsd.) (41 e) is the darkest form, with the clearest, most visible markings. curoi Calb. (41 e), found in Italy, is chalk grey and glossy, more similar to very pale examples of Apamea platinea. Its lines and the outlines of its stigmata are finely blackish grey; the median shade and submarginal line are faintly marked in grey; the orbicular stigma is absent, and the reniform stigma is smaller. The head, thorax, and abdomen match the pale color of the forewings, and have no grey dusting. The hindwing is pale dirty grey with a dark cell spot, dark veins, and black marginal lunules. ab. zetina Stgr., now classified as the full species Haderonia zetina (Staudinger, 1900) from the Thian-Shan Mts., is described as smaller, with greenish grey forewings and distinct markings.
A form from Silvaplana, Engadine, Switzerland has a uniformly grey entire forewing with no markings except the pale reniform, extending as far as the subterminal line which is conspicuously pale and preceded by a dark shade, and has a fully pale terminal area beyond; this is classified as ab. marginata ab. nov. (41 e). In transversata ab.nov. (41 e), the forewing has the median shade crossing it as a prominent blackish band. In rivalis Guen. (? Friv.) (41 e), the forewing has extensive mixed yellow scales; the recorded locality is mountains near the Sea of Marmora. The wingspan of Apamea zeta is 43–50 mm.
