The adult moths are greyish/brown with a distinctive silver coloured Y mark easily visible in the centre of both of the 'roof' shaped forewings. The hind wings are lighter in colour with a dark border giving a total wingspan of 30-40mm. The moths are active during the day feeding on nectar and can fly very rapidly. The caterpillars are 30 mm long, bright green with a white longitudinal stripe. Unusually the caterpillars have 3 pairs of prolegs (compared to the more normal number of 5) and consequently move with a distinct looping gait.