Stigmella alnetella is a moth of the family Nepticulidae. It is found in all of Europe, except the Balkan Peninsula.
The wingspan is 3.9-4.8 mm. The head is orange, the collar deep bronze-fuscous. The antennal eyecaps are white. The forewings are golden brown, becoming lighter golden towards the dorsum anteriorly. A bright shining silvery fascia beyond middle is preceded by a dark purplish-fuscous suffusion,the apical area beyond this is dark purplish fuscous. The hindwings are grey.[1] [2] [3]
The larvae feed on Alnus cordata and Alnus glutinosa. They mine the leaves of their host plant. There is usually only one mine in a leaf. Pupation takes place outside of the mine.