Caloptilia alchimiella (commonly known as yellow-triangle slender)[1] is a moth of the family Gracillariidae. It is found in Europe and the Near East.[2]
The wingspan is 10-. Forewings purplish - ferruginous ; dorsum suffused with yellow towards base ; a large triangular yellow median costal blotch, apex often rounded. Hindwings dark grey. .[3]
The moth flies from May to July depending on the location.
The larvae feed on Quercus species, Castanea sativa and Fagus sylvatica.