Wingspan about 15 mm. A number of the British Ancylis species are rather similar in appearance, whereas laetana displays an unusually whitish (for the genus) forewing ground colour.

Where the foodplants occur.

Flying in May and June in a single generation, the adults appear from dusk onwards and later come to light.

The foodplants are Aspen and occasionally Black Poplar.

The species is distributed most commonly in the south-east and south of England, but occurs in scattered locations northwards to Scotland. In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as local.

It appears to be uncommon in Leicestershire and Rutland, where there are few records. L&R Moth Group status = D (rare or rarely recorded).