Both species are about 1/8 inch long, cylindrical, and reddish brown in color. They have clubbed antennae. Differences between the 2 are very minor except that the confused flour beetle is primarily found in northern U.S. states, while the red flour beetle is usually found in southern states. The larvae are wiry and 1/8 to 1/4 inch long. They are light in color but darker around the edges (like other wireworms).

These are the most important beetle pests of flour and other stored products in homes and retail stores. Females deposit hundreds of eggs in crevices or openings in sacks of food or flour. Larvae go through many (up to 17) instars and the life cycle is greatly enhanced by warmth in heated buildings.

Flour beetles, like their name suggests, primarily infest milled grains. They will also infest ground and dried products, such as nuts, legumes, spices, and herbs, and rodent baits. They damage large amounts of flour and milled grains because they create a bad flavor in products they infest.