Wing expanse 9-15 mm. Forewing uniformly pale to medium brown. Hindwings usually somewhat lighter, sparsely scaled.

Lectotype in USNM.

Prodoxus aenescens, which coexists with it, is very similar especially in the zone of overlap (where aenescens is lighter than farther north). They can be reliably told apart through inspection of the genitalia. In the male, the valva of cinereus is of about even width throughout and it has a relatively straight outer edge. In the female, the ovipositor has a modest, non-arched dorsal ridge that tapers off at the ovipositor shaft. The larva is distinctive because of two prominent ventral hooks on the tip of the abdomen. When the two species are found together, cinereus tends to emerge somewhat earlier than aenescens.

Known from a northern limit in the transverse ranges near Los Angeles south to the US-Mexico border.

Wing expanse 9-15 mm. Forewing uniformly pale to medium brown. Hindwings usually somewhat lighter, sparsely scaled.

In coastal chaparral and montane dry shrubby grassland with Yucca whipplei (Agavaceae).

In coastal chaparral and montane dry shrubby grassland with Yucca whipplei (Agavaceae).

The species occurs throughout the southern range of its exclusive host, Yucca whipplei (Agavaceae), basically coinciding with the monocarpic varieties of the host. It feeds primarily in the basal portion of the inflorescence stalk, and usually well below cinereus where they coexist.