Grain weevils

Sitophilus zeamais, maize grain weevil
Sitophilus oryzae, rice weevil
Sitophilus granarius, granary weevil

Nature of damage

  • Infest stored grain or maize ears before harvest.
  • The larvae develop into pupae inside the kernel.


  • Removal of husks in the field will reveal weevils and the irregular punctures they make in kernels during feeding or egg laying (Sitophilus zeamais).
    - The rice weevil, smallest of the three species, rarely flies but is otherwise similar to the maize weevil, which is a strong flier.
    - The granary weevil also resembles the maize weevil, but cannot fly and lacks its four reddish spots on the wing covers.
  • In kernels dislodged from the cob, one can readily observe thread-like galleries made by the legless, stout, whitish grubs as they feed inside the kernels.

Geographic distribution

  • Worldwide distribution