Wingspan 22-28 mm. Markings are fairly consistent in southern specimens, with the 'blue border' along the trailing edge of the wings giving rise to the name. There is a northern UK sub-species, plumbata, that does not have the distinctive white markings.

It inhabits woodland, damp areas and gardens and feeds on a range of trees and bushes, including Alder and Blackthorn.

June to August.

One generation per year. It overwinters as an egg and the larvae begin to hatch from April.

Fairly widespread and moderately common throughout much of Britain. In a recent survey to determine the status of all macro moths in Britain this species was classified as common.

Fairly frequent but not common in Leicestershire & Rutland. L&R Moth Group status = B (scarce resident or restricted distribution or regular migrant)