Aseptis fumosa is a moth of the Noctuidae family. It is widespread in western North America and is known from western Canada, Washington, Nebraska, Colorado, Utah, Arizona, Nevada and California. It occurs in a variety of diverse habitats including coast chaparral, dry conifer forest, and shrub steppe. The larvae feed on Purshia (including Purshia tridentata), Cercocarpus and Ceanothus (including Ceanothus integerrimus) species, as well as Adenostoma fasciculatum. The larva is smooth green with a white subdorsal stripe and broad red and white lateral stripe.