(Linnaeus, 1758)Wingspan 18 mm.
The scientific name of this moth is derived from the rhomboid-shaped brownish blotch on the forewing.
At rest, the wings are closely folded at the tip, giving a tapered appearance.
It flies at night between late July and September, and can be attracted by light.
The larval foodplants are birch (Betula) and hazel (Corylus avellana).