Illustration from John Curtis's British Entomology Volume 6 Depicted in William BucklerThe larvæ of the British butterflies and moths 1901 Fig. 7 larva after final moult 7a pupa
The wingspan is 20–25 millimetres (0.79–0.98 in). Adults are on wing from July to September depending on the location.[2]
The difficult to see larvae feed on black horehound (Ballota nigra) and white horehound.