Length 14 to 20 mm. This is a mainly black species. The female has a broad pale band across the otherwise dark antennae; there is also a pale spot on the scutellum and at the tip of the abdomen.

Various well vegetated habitats.

Adult from June until August.

The larvae of Coelichneumon deliratorius are parasitic on various moth larvae.

Poorly recorded in Britain but probably fairly frequent.

Status in Leicestershire and Rutland not known.