Grain Weevils

Grain weevils are in the family Curculionidae and contain three highly changing pest species: Sitophilous oryzae (L.) rice weevils, S. granaries (L.) granary weevils and S. zeamais Motschulsky (maize weevils).

Adults are 0.3-0.6 cm in length and have an elongated snout containing the mouth parts that are typical of all weevils.

Grain weevils have a worldwide distribution but none thrive in tropical and subtropical regions.

They attack primarily whole grain and seeds and typically do not reproduce on fine products such as flour, but can infest formed cereal products such as pasta.

Female deposits eggs singly in holes excavated into seeds and then cover the eggs with a mucilaginous egg plug.

Adults live a long time and females can lay a large number of eggs over their lifetime.

Larvae develop and pupate within the seed and after eclosion adults chew out of the seed. Because larvae pupae and adults can occur inside whole kernels, these species can be more difficult to detect and this contribute to fragment counts in processed grain products.
Grain Weevils