Grain Weevils
Latin Name: Sitophilus granarius
What are grain weevils?
Grain weevils are stored product pests that infest whole grains and kernel-based foods. They have long, narrow bodies and range in color from reddish-brown to black.
These pests develop inside whole grains such as wheat, corn, barley, rice, and other kernels. Female grain weevils chew a small opening into a grain, lay an egg inside, and then seal the hole. Once the larva hatches, it feeds inside the grain until it becomes an adult. The adult then chews its way out, leaving behind small exit holes. These tiny holes are often one of the first signs of a grain weevil infestation.
Where will I find grain weevils?
Grain weevils can be found anywhere whole grains are grown, stored, processed, sold, or prepared. They may live in crop fields, grain storage facilities, food processing plants, grocery stores, restaurants, and homes.
Inside homes, grain weevils are usually found in kitchens, pantries, cabinets, and other areas where dry goods are stored. They are most often associated with whole grains and kernel foods.
Why do I have a grain weevil problem?
Most grain weevil problems begin when infested food products are brought into the home. Whole grains or stored products may already contain weevil larvae before they are purchased. In many cases, the infestation begins in storage or processing facilities and continues through packaging.
Adult grain weevils may also enter homes from outside. Some species are attracted to outdoor lights and can find their way inside through cracks in exterior walls, gaps around windows and doors, or other small openings.
Are grain weevils dangerous?
Grain weevils are not directly dangerous to people and are not known for biting or stinging. However, they are damaging pests because they contaminate stored food products.
In homes, they can ruin pantry items and cause food waste. In agricultural and commercial settings, grain weevils can infest large amounts of stored grain and create significant product loss.
How can I tell if I have grain weevils?
Signs of grain weevils may include small reddish-brown or black beetles in pantry areas, tiny holes in whole grains, damaged kernels, or adult weevils crawling near stored dry goods.
Because larvae develop inside the grain, an infestation may not be obvious right away. Carefully inspecting stored grains and pantry products can help identify the source.
How can I help prevent grain weevils?
To help prevent grain weevils, inspect food packaging for holes, rips, or damage before buying it. When possible, avoid purchasing grains from bulk containers, since these products may be more exposed to stored product pests.
At home, remove grains from their original packaging and store them in airtight glass or plastic containers. Rotate pantry items regularly and throw away old or expired dry goods.
To help keep adult weevils from entering, add weatherstripping around windows and doors, repair cracks in exterior walls, and replace white outdoor bulbs with yellow or LED lights that are less attractive to insects.
If grain weevils are found, inspect all stored grain products, discard infested items in sealed bags, and clean pantry shelves thoroughly to remove loose kernels, dust, and food debris.
Similar Pests: Cigarette beetle, Confused flour beetle