Elachista imatrella is a moth of the Elachistidae family which is endemic to Finland. The length of the forewings is 3.2–3.7 millimetres (0.13–0.15 in) for males and 3.4 millimetres (0.13 in) for females. The forewing ground colour of the females is mottled greyish/brownish from the base to the fascia and blackish beyond. For males, the ground colour of the forewings is greyish brown, with whitish scales basally, resulting in a mottled appearance. The larvae possibly feed on Carex species, probably Carex vaginata. They mine the leaves of their host plant.