Caloptilia alchimiella (commonly known as yellow-triangle slender)[1] is a moth of the family Gracillariidae.

Forewings purplish - ferruginous; dorsum suffused with yellow towards base; a large triangular yellow median costal blotch, apex often rounded.

[3][4] [5] The moth flies from May to July depending on the location.

The larvae feed on Quercus species, Castanea sativa and Fagus sylvatica.

This article relating to moths in the genus Caloptilia is a stub.