Sitophilus oryzae (L.)
Primary pest; grain feeder
- Adult is small (2.5 to 4 mm), dark brown with 4 distinct reddish to reddish yellow patches on the elytra.
- Adult is identical in external appearance to the maize weevil (Sitophilus zeamais); dissection required to distinguish between the species.
- Larvae are white, legless grubs that develop within the kernel and will not be detected in sieve samples or Berlese funnel samples.
- Rice, wheat, barley, occasionally peas
- Raw processed cereals such as pasta
Signs of infestation
- Increased moisture levels and heating on the surface
- Seeds with round holes formed by exiting adults
- Adults feed on whole seeds or flour.
- Larvae develop in seeds or pieces of seeds or cereal products large enough to house larvae but will not develop in flour unless it has been compacted.
- Feeding contributes to heating and infested grain is often damp due to moisture added by the insects’ respiration.
How to control
- Is distributed worldwide and across Canada
- Prefers tropical or subtropical environment but can survive temperate regions in protected situations
- Adults are able to fly.
- Adults live 4 to 5 months.
- Females generally lay eggs within a kernel but they may lay multiple eggs per kernel and more than 1 larvae can develop within a single kernel.
- Adults make a small, circular emergence hole , compared to large, oblong emergence hole made by the granary weevil.
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