Lesser Swallow Prominent Pheosia gnoma
Wingspan 45-50 mm.
A fairly common moth throughout most of Britain, this species is very similar to Swallow Prominent (P. tremula), but can be identified with care. Compared to that species, gnoma has a more distinct white wedge at the tornus of the forewing, and lacks the wavy white line in the blackish area of the hindwing.
Northern forms can show a chocolate brown head and thorax, in contrast to the typically paler-headed forms further south.
There are two generations, on the wing in May and June, and later in August. The larvae feed on birch (Betula).