Phyllocnistis unipunctella is a moth of the family Gracillariidae. It is known from all of Europe.
The wingspan is 7–8 mm. A whitish moth with yellowish suffusion and a distinct black spot near the wing apex. The forewings are shining white, posteriorly more or less ochreous-tinged; often a suffused spot on dorsum near base and a larger one in middle of disc dark fuscous; a transverse dark fuscous line at 2/3, preceded by one and followed by two dark fuscous streaks from costa; a round black apical dot; three dark fuscous diverging bars in apical cilia. Hindwings are light grey. The larva is pale green.[1] Adults are on wing in July and from September onwards, sometimes overwintering in haystacks.[2]
The larvae feed on Populus balsmifera, Populus x canadensis, Populus candicans, Populus deltoides, Populus euphratica, Populus gileadensis, Populus nigra, Populus simonii, Populus suaveolens and Populus trichocarpa. They mine the leaves of their host plant.[3]