Wingspan 36 to 44 mm. A very dull brown moth sometimes with rather inconspicuous markings, but with very white underwings.

Formerly there were thought to be two species, referred to Deep-brown Dart (A. lutulenta) and Northern Deep-brown Dart (A. luenebergensis), though at times luenebergensis was considered a subspecies or a form. A DNA review in 2024 established that all UK records are actually referable to A. luenebergensis, and that whilst A. lutulenta is a different species it is found exclusively in southern and eastern Europe. The vernacular name Deep-brown Dart is retained for all UK records, and the name Northern Deep-brown Dart is deleted.

Various habitats.

The adults are on the wing between September and October, and come to light.

The larvae feed on grasses and bushes such as Hawthorn.

Occasional in Leicestershire and Rutland. L&R Moth Group status = C (very scarce resident or rare migrant).