Wingspan 12-15 mm.
Known as 'bagworms' or 'case-bearers', the larvae of the Psychidae construct cases from fragments of plant material, in this instance, pieces of grass. The case is attached to a tree trunk or foliage, or quite often to a wooden fence or gate.
The larvae feed on grasses, lichens and decaying vegetable matter.
The adult males are plain, dull brownish moths. The females are wingless and grub-like in appearance. Both sexes emerge between May and July.
The species is fairly common throughout the British Isles, but becoming less so further north.