Knot Grass Acronicta rumicis
Wingspan 30-35 mm.
A variable species, some examples of which can resemble other Acronicta species, but this moth usually shows a curved white mark near the rear edge of the forewing, even in melanic specimens.
It is widely distributed and quite common in most of Britain, except Scotland where it is less frequent.
On the wing in May to July, there is a second brood in southern England, appearing in August and September.
The larvae feed on a range of herbaceous plants. The example shown was found on garden mint.