Adults: This moth has a wingspread of up to 20 mm. The distal half of the forewings are copper or reddish brown in colour, and the proximal half are a pale grey. The hind wings are also light coloured.
Larva: The whitish to pinkish coloured caterpillar has a brown head and thoracic shield, it attains an average length of 18 mm, has three pair of thoracic legs and four pair of prolegs. Unlike the very similar
Mediterranean flour moth, the larva does not possess a hardened (sclerotized) ring around the base of the hairs found above each abdominal spiracle.
The larva produces a strand of silk which it uses to make a feeding tunnel of frass and webbing to hide in. Heavy infestations can produce highly visible sheets of webbing over the surface of infested material, Only the larvae cause damage, they are general feeders, eating broken grains, processed foods, such as corn meal, dried fruits, seeds, nuts, chocolate, dog food, cookies, and powdered milk. The larvae prefer coarser grades of flour than the Mediterranean flour moth, The female moth will lay 200-400 eggs during an 18-day period, Larvae hatch in a couple of days and enter crevices of food, eventually feeding from within the silken tunnel, Larval development may take from 18-288 days whereupon they may travel some distance from the site of infestation to pupate in cracks and crevices or corners of ceilings and walls. The average life cycle is completed within 6-8 weeks. This moth is found flying most often at night after dusk. This moth is the most common and economically significant food infesting pest found in Ontario.