The wingspan is 32 to 40 millimetres (1.3 to 1.6 in). Forewing pale ochreous with slight dark dusting and a faint reddish tinge; veins finely defined by brown streaks, which are also distinct in the intervals; a diffuse brown shade below median vein; outer dots on veins 2 and 5 only; hindwing whitish ochreous, grey tinged along middle from base, with a postmedian line of dark grey dashes on veins. Three distinct aberrations are mentioned by Tutt, all apparently British; obsoleta Tutt, a very rare pale form, with all the dots of forewing absent, the median nervure pure white, and the hindwing white without dots; in rufolinea Tutt the colouration is bright rufous, so that the forewing appears to consist of alternate fine lines of red and white; lastly in nigrostriata Tutt the colouration is blackish, the wing appearing to be a succession of black and white lines; the shade beneath median vein is almost black, and the hindwing is much darker; the majority of these darker forms are males.[1]
Similar species
Mythimna straminea is difficult to certainly distinguish from its congeners. See Townsend et al.[2] for genitalia images and an identification key.
The moth flies from June to August depending on the location.
Larva ochreous with grey freckles; lines paler edged with dark grey; subspiracular line paler. The larvae feed on Phragmites and Phalaris.[3]
References
^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
