One bug that looks like a flax seed is the adult weevil. This little brown beetle has a long snout, and its body is shaped somewhat like a kidney bean. The weevil typically measures about 1/8 inch in length. Another type of bug that resembles a flax seed is the rove beetle. This black or dark brown beetle also has a long body, but its shape is more oval-shaped than the weevil's. Rove beetles typically grow to be about 1/4 inch in length.