Pupa: Pupation occurs inside the case. The larva walks up a vertical surface and attaches the case at both ends with silk. One end of the case is then modified. The larva cuts a short slit along both edges to make that end flatter, which acts as a valve. Before eclosion the pupa pulls itself halfway through the valve. The new moth emerges around noon, leaving the pupal case exposed on the outer case.
Adult: Adult females have a wing span 10 to 13 mm long. They are gray with up to four spots on the fore wings, and a brush of long, lighter gray hair-like scales along the posterior margin of the hind wings. Males are smaller (wing span: 7 to 9 mm) and thinner than the female, with a less distinctive wing pattern.