Wingspan 12-14 mm.
A local and scarce species, occurring in a few wetland localities in East Anglia. It formerly was also found in Northumberland.
The adults are rather similar to A. badiana but have a white outer edge to the median fascia, and three or four blackish dots below the apex of the forewing.
The moth has two generations, and is on the wing in May and June and subsequently late July to August.
The larvae feed on marsh pea (Lathyrus palustris), spinning two leaves together.