Pacific Pests, Pathogens and Weeds - Online edition

Pacific Pests, Pathogens, Weeds & Pesticides

Rice (lesser grain) weevil (338)

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  • Worldwide distribution. On rice, maize, sorghum, wheat, cassava, and other stored products. Important weevil.
  • Destructive: attacks sound grains, leaving large cavities, allowing secondary invasions by insects, mites, and fungi.
  • Eggs laid into holes chewed in grain, and then plugged. Larvae feed inside the grain, and pupate there. Adults, up to 4 mm, reddish-brown to black with four light-reddish to yellowish spots on the wings.
  • Spread with movement of stored grain; the weevil is not a strong flyer.
  • Cultural control: harvest at maturity; dry to 12%; keep storage rooms and areas clean; spray bins, and use new sacks; if infestations occurs, locate and treat: if small - sieve, freeze or wrap in plastic and bury; if large, fumigate. Store small amounts of grain in plastic containers.
  • Chemical control: consult full fact sheet for details; always check whether the product is for treating equipment, bins and buildings or for treating grain for human use and animal feed. READ THE INSTRUCTIONS. 
Common Name

Rice weevil, lesser grain weevil, small snout weevil

Scientific Name

Sitophilus oryzae; a similar species (Sitophilus zeamais) attacks maize (see Fact Sheet no. 339).

AUTHOR Grahame Jackson
1Information from Swaine G (1971) Agricultural Zoology in Fiji. Her Majesty's Stationery Office. London; and CABI (2015) Sitophilus oryzae (lesser grain weevil). Crop Protection Compendium (; and Rickman J, Gummert M (undated) Pest management in storage. IRRI. (; and from DPI&RD (2019) Insect pests of stored grain. Agriculture and Food. Government of Western Australia. ( Photos 1&2 Clemson University - USDA Cooperative Extension Slide Series,; Photos 3&4 Walker K (2006) rice weevil (Sitophilus oryzae): PaDIL - (

Produced with support from the Australian Centre for International Agricultural Research under project PC/2010/090: Strengthening integrated crop management research in the Pacific Islands in support of sustainable intensification of high-value crop production, implemented by the University of Queensland and the Secretariat of the Pacific Community.

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