Rice Weevil and Granary Weevils

Last updatedLast updated: July 12, 2022
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The rice weevil and granary weevil are pests of stored grain and seeds. They develop inside whole grain kernels as small, white, wrinkled, grub-like larvae. There is generally no external evidence that the larvae have been eating and growing inside the seed until after about one month when the adult weevil chews through the seed coat and emerges. The adult weevils are 1/8th inch long and have slender, hard-shelled bodies that appear pitted or scarred with tiny holes. They are brown to reddish brown in color. The rice weevil has four faint yellowish spots on the back of the abdomen. The granary weevil is uniformly colored with no spots.

Presence of rice or granary weevils inside the home usually indicates there is infested whole grain or seeds. This may be food seeds or beans in the cupboards, popcorn, saved garden seeds, dried seed decorations, decorative Indian corn, “bean bags,” old grain-based mouse bait, or other stored seeds.

Rice and granary weevils are harmless to people, houses, furniture, clothing and pets. They cannot bite or sting and they do not carry diseases. They will not feed on furniture, the house structure or other items. The harm they do is destruction of the seeds they infest and the annoyance of being in the wrong place.

Control requires locating and eliminating the infested whole grain. Small quantities of grain can be “saved” by controlling the weevils with heat or cold. Heating grain to 140 degrees F for 15 minutes or freezing at O degrees F for 3 days will kill all stages of weevils in the grain. Larger quantities may require disposal or professional fumigation.

Cupboards or shelves holding infested items should be emptied and thoroughly vacuum cleaned, paying special attention to cracks and corners. A light spray of household insecticide can be applied to cracks of empty shelves but spraying without locating and eliminating the infestation will not eradicate the problem.  AirDevil is a low odor, crack and crevice aerosol which works well when eliminating weevils.  For large infestations, use Suspend SC to kill the weevil population.

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