Stigmella trimaculella is a moth of the family Nepticulidae. It is found in most of Europe, east to the eastern part of Palearctic realm.
The wingspan is . The thick erect hairs on the head vertex are ochreous-yellowish. The collar is white. Antennal eyecaps are whitish. The forewings are dark fuscous; a broad median longitudinal patch extending from base to near middle, and large opposite sometimes confluent triangular costal and dorsal spots beyond middle whitish-yellowish. Hindwings are grey. Abdomen of male yellowish, crimson-tinged. External image
Adults are on wing in May and again in August.
The larvae feed on Populus alba, Populus angustifolia, Populus x canadensis, Populus candicans, Populus canescens, Populus deltoides, Populus nigra, Populus simonii, Populus suaveolens, Populus tremula and Populus trichocarpa. They mine the leaves of their host plant.