Weevils are small beetles that feed on plants, especially grains. Their larvae are often found in packaged food, such as flour, cornmeal and cereals, and can appear in dog food. These young weevils don't make their way into sealed packages; they are already in the food as eggs.
Weevils, whether in larval or adult stage, are not harmful to humans or animals. Although it may seem unsavory to you, they can be eaten along with any food they have infested without causing any ill effects. The biggest problem weevils pose is to food producers, who sometimes have to take action to keep them out of crops and processes. In some cases, weevils benefit humans by serving as test subjects to determine whether residue from pesticides remain in harvested grains. If weevils eat the grains and die, observers know pesticides are present.