A large crambid (23-31 mm wingspan). Antennae of males unipectinate, actually serrate with fine ciliations. Forewing ashy gray to whitish brown with median white streak, the white streak bounded above by a thicker dark brown line which eventually runs into the apex; seven dark dots in terminal row. The male genitalia are illustrated by Landry (1995). Alberta material belongs to the subspecies nortella Kft. Similar to T. pexella coloradella, but the latter has the oblique line darker, males have bipectinate antennae, and pexella tends to fly later.