The term GRAIN PEST can be summarized as a pest that affects grains, and the most common of these pests is the WEEVIL, which has six letters. Weevils are small beetles that feed on stored grains, such as wheat, rice, and corn, and can cause significant damage to crops. They lay their eggs inside the grain kernels, and the larvae then feed on the grain, leaving behind empty shells. Weevils can also spread diseases and contaminate food supplies, making them a major agricultural pest.