Elachista trapeziella is a moth of the family Elachistidae found in Europe.
The wingspan is 8–.The head is grey, face white.Forewings are blackish ; a spot on fold towards base, one on middle of costa and another beneath it on fold, in female larger and sometimes confluent, a fourth on tornus, and a fifth at apex shining white. Hindwings are dark fuscous. The larva is greenish-grey, faintly reddish tinged.[1]
Adults are on wing from June to August.[2]
The larvae feed on white wood-rush (Luzula luzuloides), hairy wood-rush (Luzula pilosa) and greater wood-rush (Luzula sylvatica). They mine the leaves of their host plant. Pupation takes place outside of the mine.[3] They are pink with three cream-coloured length lines and a black head. Larvae can be found from autumn to April or June of the following year.[4]
It is found from Fennoscandia to the Pyrenees and Italy and from Ireland to Slovakia.