hymenopus coronata

Conrad Bérubé
island crop management
email: uc779(at)freenet.victoria.bc.ca

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Granary Weevil

Information on this page is derived from public domain documents published by the federal government of canada, the provincial government of British Columbia and information contributed on electronic discussion groups. Please bear in mind that any pesticides mentioned in these pages may no longer be recommended or registered for the indicated use — check with your local pesticide officer or regional agrologist for current info (you can use the provincial directory on the internet to search for those job titles or call Enquiry bc at 1 800 663-7867 for assistance). It is recommended that you use a search engine using the common name and/or scientific name of the organism(s) below, together with the name of your province, to find biology and management information relevant to your local conditions.

If you choose to use chemical controls remember to
always follow pesticide label instructions!

insects of economic importance in Canada and British Columbia

family: curculionidae
species: sitophilus granarius
common names: granary weevil
natural enemies: grains, nuts


Granary Weevil       Granary Weevil

Agriculture and Agri-Food Canada Insect Identification Sheet No. 80 March 1981

Granary Weevil

Sitophilus granarius (L.)

The granary weevil, which is found throughout the world, attacks all small grains and hard cereal products such as macaroni. In Canada, it is somearial found in prairie grain elevators, but is more common in farm storage areas in southern Ontario.


The insects feed on the kernels, leaving only the hulls, and a severe infestation can reduce stored grain to a mass of hulls and frass. They often prepare the way for other insect species that feed on damaged kernels but are unable to penetrate sound grain. In addition, the feeding weevils contribute to grain heating and further damage.

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Life History:

The adult is a polished chestnut brown or blackish beetle about 5 mm long, with a head that is prolonged into a long, slender snout. The adults, which are unable to fly, live for 7 to 8 months and during this period each female lays about 150 eggs. In egg-laying, the female drills a small hole in the kernel, deposits an egg in the cavity and seals the hole with a gelatinous secretion. There is only one larva in each infested kernel. The white, legless grub completes its growth, pupates and develops into an adult weevil within the kernel. After reaching the adult stage, it eats its way out of the kernel. In summer, the life cycle may be completed in 4 weeks. Infestation can start at temperatures as low as 15 degrees but optimum development takes place at about 30 degrees and at a relative humidity of 70%.


Granary weevils can spread in grain residues. Because most of the insect's life cycle occurs inside the kernel, an initial infestation is difficult to detect. A heavy infestation can be treated with an approved fumigant or, in winter by cooling the grain to a temperature of -7 degrees and holding this temperature for at least 6 weeks. Consult your provincial agricultural representative for full details on controlling the pest.

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Copyright © 2007 Conrad Bérubé, site design, concept and scripting. All rights reserved worldwide.
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