Wingspan c.7 mm.
This rather local species is distributed in the south and south-east of England, and is generally uncommon. The tiny white adult moths are at large in two generations, in July and from September through to April. The overwintering adults are sometimes found in thatch or haystacks.
The larva feeds on willow, particularly on purple willow (Salix purpurea), sometimes on other smooth-leaved willows, such as crack willow (S. fragilis). The larva mines in the lower epidermis, forming a translucent mine, then moves into the twig via the petiole, eventually returning to a second leaf.
Larval mines are best looked for in June, or in August/September.