Granary Weevils

How to identify Granary Weevils

Adult granary weevils are easily recognizable for their uniform reddish-brown colouration. They have a cylindrical shape and average between 3 and 5 mm in length. While granary weevils possess wings, they are unable to fly. Larvae appear as white, legless grubs.

Signs of an infestation

Perhaps the most detrimental aspect of granary weevil infestations is their ability to go undetected until substantial damage is already inflicted. Since larvae mature inside kernels of grains and adults also spend much of their time inside infested product packages, humans rarely see the insects. To detect granary weevil infestation, homeowners should monitor stores of the pest’s favourite products. Affected grains will appear wet and individual kernels will be riddled with holes.

Granary Weevils Removal

The best way to remove granary weevils is to throw away infested products. Individuals dealing with large numbers of the pest should contact a professional pest removal service. Orkin Canada pest specialists have the tools to completely eradicate populations of granary weevils and sanitise affected areas of homes.

How to prevent Granary Weevils from invading

The prevention of granary weevil infestation hinges on proper storage of grains and sanitation of storage bins. Airtight containers prevent the pests from infiltrating products. Homeowners should also be mindful of the temperature at which grains are stored. Freezing grains can kill off small infestations and stop the spread of granary weevils. Finally, storage bins should be thoroughly rinsed and dried before and after use.

Habitat, Diet, and Life Cycle

Habitat

Uniquely, granary weevils thrive in cool, temperate regions, which makes them prominent in the Northern United States and Canada. The pests are common nuisances in British Columbia, Alberta, Saskatchewan, Manitoba, and southern parts of Ontario. Granary weevils are worldwide in distribution.

Diet

Granary weevils eat the same grains in which they breed. They prefer whole grains and seeds like corn, rye, oats, barley, sunflower seeds, bird seeds, and popcorn. Adults may also be found in cereals and pastas.

Life Cycle/Reproduction

A single adult female is able to produce approximately 150 eggs during her lifespan. Granary weevils use their powerful mandibles to drill holes in grain kernels, deposit a single egg, and then fill the hole with a gelatinous material before moving on to the next kernel. The eggs hatch in about three days, and, depending on the temperature, larvae may need anywhere from 30 to 40 days to mature. Adults live between seven and eight months.

Commonly Asked Questions

General Facts

Thousands of species of weevils exist throughout North America, and granary weevils are among the most aggravating. As stored product pests, these weevils deposit their eggs into grain kernels and can render products unfit for human consumption. Since both adults and larvae feed on grains to survive, infestations of the pest are able to cause widespread damage.

Problems Caused by Granary Weevils

Granary weevils do not bite people, spread disease, or cause structural damage to homes or furniture. The damage they cause is almost exclusive to pantries and other stores of grains. The development of granary weevil larvae causes infested grains to heat, which in turn encourages the growth of fungi and sprouts. Infestations can lead to significant financial losses, especially in warehouses and food processing plants.