Mother of Pearl

The wingspan is 26–40 millimetres (1.0–1.6 in). The forewings are pale whitish-ochreous, yellowish-tinged; a grey subcostal suffusion and connected orbicular dot; lines rather dark grey, first straight, second serrate, curved, strongly broken inwards beneath middle; a dark grey discal mark, nearly followed by a grey blotch; a grey terminal band, edge parallel to second line. Hindwings with colour, discal mark, and posterior markings as in forewings. The caterpillar larva is whitish green, sides greener; dorsal line darker; head green. The larvae feed mainly on stinging nettle (Urtica dioica), as well as small nettle (U.urens). Less often they have been found on hops (Humulus lupulus), another member of the urticalean (nettle) clade of the Rosales. From the Caryophyllales, goosefoot (Chenopodium) and orache (Atriplex) have been recorded as occasional foodplants. They are notable for their rolling locomotion; the rolling behaviour of the caterpillar has been used as a model to create next-generation robots that roll.