Wingspan 14-17 mm.
With its blackish ground colour and creamy spots and cross-lines, this is quite a distinctive species, which flies in the daytime.
It occurs on chalky downland in the south of England and the limestone pavements of Cumbria and Westmorland.
The adults are on the wing in two overlapping generations from late April to about October.
The larvae feed on wild herbs, particularly thyme (Thymus) and marjoram (Origanum).