Adults have a wingspan that is about 5/8-3/4 inches wide, wing tip to wing tip. Wings pale gray but 2/3 is reddish brown with a coppery luster.
Mature larva usually about 1/2 inches long. They can be white and very to a greenish, pinkish, or a brownish hue depending on its food. The head is prothoracic plate/shield yellowish brown to reddish brown. They have 5 pairs of well-developed prolegs on abdomen and each bearing crochets.
The cause no damage except the nuisance that they are when they reach high numbers. The larvae are surface feeders and generally produce a lot of webbing throughout the infested parts of materials. They are general feeders and attack grain and and most dried foods. They prefer the coarser grades of flour such as whole wheat, graham flour, and cornmeal, but they can breed in shelled or ear corn.
These moths and their larvae are commonly mistaken for cloth moths. Adults are attracted to light.
At night the female lays 100-400 eggs, singly or in small groups, on the larval food material during the period of 1-18 days. Upon hatching, the larva establishes itself in a crevice of the food material. It feeds in or near a tunnel like case it has webbed together of frass and silk. the larval period lasts 13-288 days, depending primarily on temperature and food availability. When the last instar larva is ready to pupate, it leaves the food and wanders about until a suitable pupation site is found. There are usually 4-6 generations per year. The life cycle typically is 25-135 days days.
Plodia interpunctella Hubner