Larvae:
Larvae are a white, “straight”, elongated and worm-like with a dark head. Up to 6.0 mm long.
Adults:
The adults of both species are a slim beetle, 3.0-4.0 mm long. Both are a reddish brown colour.
The red-rust flour beetle antennae end in a 3-segmented club whereas the confused flour beetle has an antennae that thickens gradually towards the tip.