Adults are 1/8 to 1/4 inch long with a reddish-brown coloring, though they can be darker or mottled (as with rice weevils). They can be difficult to tell apart. These weevils have snouts containing elbowed antennae and chewing mouthparts. Larvae are white, legless, and wedge shaped.

Females bore into whole seeds or grains to create a cavity in which to lay an egg, and then seal the hole with a gel secretion. The egg hatches in a few days to feed and develop within the seed or grain. The life cycle can be 1 to 5 months depending on temperature. Adults can live up to 8 months and females lay 200 or more eggs. Adult granary weevils do not fly, but rice and maize weevils can fly.

Rice weevils are considered to be among the most important stored product pests. They do not tolerate the temperate cold of the northern states but persist outdoors in southern fields. They are present in stored grain year-round. Granary weevils can do extensive damage over time to whole seeds and grains kept in storage for periods of time. They tend to be contained to infested areas due to a lack of mobility. Both are world- wide pests spread by human activity. Maize weevils will attack standing grains, ornamental corn, and similar products in storage. They will feed on whole kernels and processed grains, including pasta. Maize weevils have also been found to attack stored apples.