The wingspan is 30–35 mm. Its forewings are purplish fuscous, more or less greenish tinged, with a paler patch beyond the cell; prothorax conspicuously whitish. — ab. sundevalli Lampa is a form in which both forewing and thorax are entirely dark olive green. ab. nigra Tutt has the forewing black throughout, without any green tinge, and has only been taken in the North of England; lastly, in ab. coronula Haw. the white apex is suffused with grey brown instead of green, with a white lunule on its inner edge.[1] The white patch distal to the reniform appears to resemble a crown, hence the name coronet. Wing coloration and size is dependent on the environmental factor in which they grow as well as it is expected to be shown through physical differences and morphology.[2][3]
^Seitz, A. Ed., 1914 Die Großschmetterlinge der Erde, Verlag Alfred Kernen, Stuttgart Band 3: Abt. 1, Die Großschmetterlinge des palaearktischen Faunengebietes, Die palaearktischen eulenartigen Nachtfalter, 1914
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