Cosmopterix turbidella is a moth of the family Cosmopterigidae. It is known from the Canary Islands. The wingspan is 7-8 mm. The larvae feed on Forsskalea angustifolia, Gesnouinia arborea, Parietaria debilis and Parietaria officinalis. They mine the leaves of their host plant. The mine starts as a corridor that runs from the midrib in the direction of the leaf margin, following a lateral vein. Later, the corridor widens into an irregular blotch. Most frass is ejected through a hole in the first section of the mine. Much of the frass grains are captured by spinning under the leaf. A single larva makes several mines.