Wingspan 11 to 14.5 mm. The adult moth has yellowish ochre veins.

Around its preferred food plants, black horehound and hedge woundwort but it is occasionally found on other Labiates.

The adult flight period is from late June to August, sometimes coming to light.

The species is quite easily identified at the larval stage by its distinctive case made of rings of mined leaf, fully developed in May. The mines are large and obvious on the upper side of the leaf, betraying the larva or larvae on the lower side. Cased larvae occur from September to May, but are small until March, after the winter diapause.

Found mostly in southern England and Wales, but it becomes scarce and local in Cheshire and from south Yorkshire to the northern limit of England. In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as local.

It appears to be uncommon in Leicestershire and Rutland, where there are few records. L&R Moth Group status = D (rare or rarely recorded).