Larger grain borer and the grain weevils

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(Prostephanus truncatus) (Sitophylus spp.)

Credits:Biovision-infonet

Adult beetles of Maize weevil (Sitophilus zeamais) in maize. Adult emergence holes with irregular edges are apparent some weeks after the initial attack.
(c) University of Georgia Archives, University of Georgia, Bugwood.org
Larger grain borer (Prostephanus truncatus). The adult beetle is 3-4.5 mm long.
(c) NRI/MAFF. Reproduced from the Crop Protection Compendium, 2004 Edition. (c) CAB International, Wallingford, UK, 2004
The maize weevil (Sitophilus zeamais) adult. It is possible to confuse the maize weevil with other storage insect pests such as the larger grain borer – LGB (Prostephanus truncatus). The end of the body of the maize weevil is more rounded than that of the LGB.
(c) USDA, ARS (Public Domain

They attack stored maize grains. Both the adults and the larvae (grubs) of these beetles feed in the grains. Adults come from infested cobs in the field or from an infested maize store and lay eggs in the grains. They attack maize both in the field and after harvest. Attacked maize grains lose all their contents and are not fit to eat. These pests become a serious problem in short time if no control measures are applied. The larger grain borer also attacks dried cassava roots and even the wooden structures of the stores.

What to do:

  • Conserve natural enemies. An imported predatory beetle Teretrius (formerly Teretriosoma) nigrensis has been released in several African countries in an attempt to control the larger grain borer.

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