Agonopterix triallactis is a moth in the Depressariidae family. It was described by Meyrick in 1935. It is found in Morocco. The wingspan is about 20 mm. The forewings are pale greyish-ochreous with very faint pinkish tinge and a small indistinct blackish dot at the base of the dorsum. The stigmata are black, the first discal minute or obsolete but additional dot obliquely above and before it well-marked and rather obliquely before the plical. There are five small indistinctblackish marginal dots on the apex and termen. The hindwings are light grey, the veins and terminal edge darker.