The flour beetle is a common pest insect known for attacking and infesting stored flour and grain. They are small, about 1/8 to 1/4 inch in length, and reddish-brown in color. "They are one of the most common and most destructive insect pests for grain and other food products stored in silos, warehouses, grocery stores, and the home."[1] While flour beetles cannot feed on whole, undamaged grain, they are often found feeding off of broken grain, grain dust, and other household food items like flour, rice, dried fruit, nuts, and beans.

[1] Wikipedia