Adult : 16mm (with wings spread), pale-grey wings, with outer two-third of front wings reddish-brown with coppery shine; Larvae : 9-19mm long, dirty white to pinkish/greenish/brownish body (depending on food), with yellowish-brown to reddish-brown head, 5 pairs of well developed pro-legs on abdomen.

Eggs (up to 500 per female) laid on surface of produce or dropped between sack fibres. Entire life cycle takes between 25-135 days, depending on conditions.

Adults do not feed and are short-lived. Larvae are serious pest of cereals (prefer broken grain) and processed food. They are surface feeders and produce a lot of webbing and frass throughout the infested part of the material, thus also contaminating it. In heavy infestations, webbing can completely cover the surface of the produce.