Adult beetle length 3 – 4.5 mm
The shape is elongated; the antennae have a gradual five segmented club. Easily mistaken for the rust-red flour beetle, which has distinct three clubbed antennae. The cylindrical wiry larva is 4 to 5 mm long when fully grown and is white tinged with yellow. It has a pair of immovable projections, urogomphi, on the final abdominal segment.