Wingspan 15-20 mm.
An adventitious species, this moth was introduced into Britain, and is now well established throughout. Formerly known as B. lignea, this in fact was a misidentification of 873a B. vittata, for which lignea is now a junior synonym.
Occurring mainly in August and into September, and nocturnal, it is a common visitor to the light-trap in many areas.
The larvae feed on a variety of foodstuffs, including decaying vegetable matter.
Larva: (description Ian F. Smith)
Foodplant: In and on soft damp Dipsacus fullonum seedheads. January. (Emmet states 873 feeds on live and decaying conifer foliage, bird droppings and other dead or live organic matter, Sept.-June)
Length: 5 mm to 9 mm in January.
Head: Shiny dark chestnut brown. Frons slightly paler, with dark adfrontal border. Clypeus and labrum pale. Mandibles reddish brown with darker teeth.
Prothorax (T1): Large oval pitchy brown subspiracular and subventral pinacula.
Prothoracic shield: Large, covering all T1 dorsally and laterally down to the spiracle. Pitchy brown, darker than head. Divided by fine pale brown medial line.
Thoracic legs: Coxa concolorous with venter. Femur and tibia dark brown. Tarsus and claw brown.
Body: 9 mm larva described, 5 mm larva has paler abdomen. Dorsally brown, with a purplish tint in some light. Ventrally paler with prominent black spots on segments A1,2,7 and 8.
Spiracles: Unobtrusive, small, concolorous.
Pinacula: Large, shiny, pitchy brown.
Setae: Translucent. Basally pale brown, fading distally.
Anal plate: Shiny yellowish brown with a broad dark brown transverse band anteriorally.
Prolegs: Concolorous with venter. Crochets brown.