Common in damp pastures, damp heathland and mosses throughout the British Isles, except for the far north. Wingspan 9-12 mm. Smaller than
A. reaumurella. Day-flying in bright sunshine, sometimes in small, loose, low-flying swarms when conditions are favourable, but never in such large swarms as
A. reaumurella; widely distributed across Hampshire and the Isle of Wight. Larva feeds within seedpods of Cuckoo-flower and Garlic Mustard, subsequently feeding on the leaves, living within a movable case, and over-wintering as a pupa.