Wingspan 10–12 mm.

Head slender, blackish brown to black wit posterior, triangular, membranous, yellow area; prothoracic plate dark brown, bisected; abdomen long, orange-yellow with distinct constrictions between segments; anal plate concolorous with abdomen. The thoracic feet are reduced to stumps (Gregersen & Karsholt 2022).

Yellowish, upper-surface, in the end strongly inflated blotch.

The larva makes a linear mine, normally starting half way up the leaf and going upwards, about 10 cm in lenght. It hibernates in a silk covered chamber in the mine where it pupates with the head upwards. Tenanted mines can be found in September/October, they are invisible and impossible to find after hibernation.
The adults come to light.

The monophagous larva lives on Ammophila arenaria.

It inhabits coastal areas and dunes.