Wingspan 13 to 19 mm. When well-marked this species is fairly distinctive, poorly-marked specimens are difficult to separate from other Bactra species.

This species occupies damp marshy habitats.

The adult moths fly in June and July.

The larvae feed in the stems of rushes such as Common Club-rush and Compact Rush hollowing out the stem.

Fairly frequent locally over much of the British Isles. 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).