Wingspan 17 to 20 mm. One of the more distinctive Agonopterix species, with its combination of well-marked purplish-brown forewings and buffish thorax and head.

Areas where the larval foodplant is common.

The normal flight period for the adults is July to August, when the species is attracted to light.

The larva feeds on St. Johns-wort spinning together the shoots and feeding within.

Locally scattered in England and Wales, becoming less frequent into Scotland. In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as local.

It appears to be uncommon in Leicestershire and Rutland, where there are few records. L&R Moth Group status = D (rare or rarely recorded).