Wingspan 10-13 mm.
A springtime species, flying in April and May in the north; in the south a later second generation also occurs.
The moths fly low over the foodplants in sunshine and have conspicuously white hindwings.
The larvae feed on bitter vetch (Lathyrus linifolius) and bush vetch (Vicia sepium), spinning the leaves together or living inside the seed pods.
It is a reasonably common species over much of the British Isles.