Wingspan 23-26 mm.
This pretty species is very local and almost entirely confined to the county of Kent, although recent light trap records may suggest that it is less scarce than some textbooks would indicate.
It inhabits grassland and chalk quarries where the food plant occurs, mainly on the North Downs. It flies in the second half of July and early August at dusk and later comes to light. On warm nights it has been recorded well away from its normal habitats.
The larvae feed on marjoram (Origanum vulgare) and spin the leaves of the terminal shoots together when fully grown.