The Dark Arches is quite variable in ground colour, ranging from pale greyish, brown to blackish. It has conspicuous oval and kidney marks, dark V-shapes either side of the thorax, and a W-mark near the outer edge. All these are distinguishing features and remain fairly constant even if there is a difference in colour. Wingspan up to 55mm.
The caterpillars feed on various grasses. The adults fly June to August, sometimes September to November in the south. Fairly attracted to light, and often comes in large numbers. Found in all types of habitats, including gardens, woodland, hedgerows, marshes, and arable land. Common and widespread throughout.
Photographs of Dark Arches (Apamea monoglypha) taken in July 2015, rear garden, Staffordshire. © Pete Hillman 2015. Camera used Nikon D3200, with Sigma 105mm macro lens.