Wingspan 7 to 8 mm. A tiny whitish moth with some yellowish suffusion and a distinct black spot near the wing apex. The larva mines the leaves of Lombardy Poplar,  hybrid Black Poplar and other poplars, producing a winding, thin, silvery, translucent gallery resembling a 'snail trail' in the upper epidermis of the leaves which leads towards the leaf edge. It then folds the leaf edge over and pupates in a cocoon in the fold.

Phyllocnistis xenia makes similar mines on Grey or White Poplar

Adult Leafmine

Where the larval foodplants occur.

The adults fly in July and from September onwards, overwintering sometimes in haystacks.

It is fairly common in most of England, becoming scarcer further north. In the Butterfly Conservation's Microlepidoptera Report 2011 this species was classified as common.

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

http://www.leafmines.co.uk/html/Lepidoptera/P.unipunctella.htm

https://bladmineerders.nl/parasites/animalia/arthropoda/insecta/lepidoptera/ditrysia/gracillarioidea/gracillariidae/phyllocnistinae/phyllocnistis/phyllocnistis-unipunctella/