The weevils include approximately 40,000 described species, and this is therefore one of the largest groups of insects known to man. Weevils have mouth parts that are located on the tip of a proboscis-like protrusion. The nut weevil is a commonly known beetle, which is responsible for the wormholes you see in ripe hazelnuts. The nut weevil larvae live inside the nut before it is ripe and it does not infest ripe nuts. Weevils of the genus Apion are associated with different kinds of seeds prior to harvesting. They are often dragged into warehouses with peas or beans, but this is often irrelevant, because they do not thrive in mature dry seeds in a warehouse.
Among the many weevils only three species are able to breed in stored foods: the granary weevil, the rice weevil and the corn weevil. They belong to the genus Sitophilus, but are often described under their old name: Calandra.