H. humuli is a fairly large moth having a wingspan of 40–70 mm. This species shows a very notable sexual dimorphism: the forewings of the male are silvery white with buff fringes while the highly variable female has yellowish forewings with inconstant orange to brown markings. In general, the female is also considerably larger than the male. The antennae are strikingly short and the moths lack functioning mouth parts so they cannot feed.

The caterpillar is pale yellow with some scattered implanted dark-coloured hairs. The head is brown and the lateral sides carry distinctive blackish stigmata.

Females of this species scatter their eggs over plants as they fly over them in a suitable biotope. The larva lives on the roots of grasses and small herbaceous plants. It hibernates as a larva once or twice and pupates in a cocoon in the ground. The adults are active from dusk onwards and, later on, come to light.

Roots of Gramineae and small herbaceous plants like Humulus lupulus and Rumex spp.

This species can be found on roughs, along field edges and roadsides and in gardens.