Wingspan c. 13 mm.
Rather larger than similar-looking Glyphipterix species, G. haworthana is locally distributed throughout Britain in suitable habitat where the foodplant, cotton-grass (Eriophorum) grows. In northern Britain it is regular on wet moorland.
The larva feeds on the seeds of the foodplant, spinning the cotton heads together or to nearby vegetation, making them noticeable in late winter or early spring.
The adults fly during May.