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Head cream-coloured, antennae banded with brown on each segment, labial palpi porrect, dorsally cream, ventrally brown. Thorax of a cream colour, tegulae and metathorax yellowish-brown. Forewings strongly hooked, a characteristic shared by many species in the genus Ypsolopha. Dorsal surface of forewings brown, with pale yellow scales on the basal one third of the wing, extending lengthwise and proximally, near the thoracic junction. Hindwings uniformly light grey, somewhat translucent proximally and basally. Ventral wing surfaces uniformly light grey. Legs and abdomen light grey. This species can be distinguished from the similarly looking Ypsolopha canariella by its mostly brown forewings, whereas canariella has mostly yellow forewings, with brown scales restricted to a triangular area in the middle of forewing. Ypsolopha dentella, another similar species, has a whitish band on the basal one third of the forewings, which does not extend to the lateral wing margin. There is also a well-defined, whitish "spine" pointing upwards and away from the wing base.

Throughout North America, becoming scarcer in the east due to the diminishing presence of its host plant (Idis and Grafius 2001). In Canada it occurs in most provinces, being most frequently collected in B.C. (Scudder and Cannings 2007) and Alberta (Bowman 1951). It is not known from Ontario, but Profant (1991) collected it in Michigan.

According to Greg Pohl (pers. comm.) Ypsolopha dentiferella and frustella are conspecific. The differences are clearly not morphological. Like most microlepidoptera genera, Ypsolopha is in need of a major revision, especially given the doubtful autapomorphy of a phallic caecum. The present work treats frustella as a synonym of dentiferella.