Weevil Bug: How to Get Rid of This Pest

A member of the family Curculionidae, the weevil bug is like a beetle with some interesting upgrades. "Weevils that infest food items are tiny, but you can see their distinctive 'beak-like' snout jutting out from the head," says David Lofquist, region technical training manager at Arrow Exterminators in an email interview. In fact, the weevil's mouthparts are located at the very end of this trademark snout.

However, with more than 3,000 species in North America alone, weevil size and appearance can vary pretty widely. They range in size from 0.10 inch (3 millimeters) to 0.25 inch (10 millimeters).

To tackle a weevil infestation, you must first correctly identify the specific type of weevil in your home. The most common types of weevils include:

Rice Weevil (Sitophilus oryzae)

A major pest of stored grain, the rice weevil is known for its ability to damage stored grains like rice, wheat, and corn. They are small, dark-colored beetles with a long snout and four light-colored spots on their backs.

Granary Weevil (Sitophilus granarius)

Similar to rice weevils, granary weevils also infest grains. They differ in that they cannot fly and are slightly larger. These pests are particularly harmful to stored dry food products like wheat, oats, rye, barley, rice, and corn.

Maize Weevil (Sitophilus zeamais)

Very similar to rice weevils, maize weevils are slightly larger and predominantly infest stored corn. They are also known to infest other grains and have a worldwide distribution.

Bean Weevil (Acanthoscelides obtectus)

Despite its name, the bean weevil is not a true weevil but a member of the leaf beetle family. It primarily infests dried beans and other legumes, causing significant damage.

Black Vine Weevil (Otiorhynchus sulcatus)

Similar to vine weevils, these pests are known for attacking ornamental plants as well as fruits like blueberries.

There are other common types, including the wheat weevil and the rose weevil. Each type has its unique characteristics and preferred habitat, but they all share the common trait of being potentially damaging to crops, stored foods, and garden plants.

If you find insects inside stored cereal grains, beans or seeds, then weevils are the likely culprits. "Commonly infested items are bird seed, pet food, or wildlife feed containing seeds or corn," says Lofquist. "Oftentimes, the infestation begins in the garage or basement and then spreads to a pantry."

Typically, weevils are found in a product that has been stored for six months or longer, he adds. Although it's possible to find adult beetles feasting on flour, it's not likely, as they can't use the flour to continue their life cycle. "That's why identification is important because flour beetles or other scavenging type pantry pests may be the issue [instead]," he says.

Unfortunately for people who appreciate insect-free pantries, these little buggers like to infiltrate the area, but not in the way you might think. We already mentioned that infestation can start in the garage or basement, but that's not the most likely cause.

"These pests usually come indoors via packaged foods or bulk products," says Ben Hottel, technical services manager for pest-control service Orkin. So, the odds of a weevil flying into the pantry are low, thankfully. It's much more common to bring them home with you from the store.

Once weevils infiltrate the pantry, they can go undetected for quite a while. "Weevils lay eggs inside the kernels of grains or other starch products that are large enough for the larva to develop inside," Hottel explains. "Because the larva develops inside the kernels of grains, weevils can remain hidden in the pantry for a long time."

The weevil life cycle is pretty interesting, if also disgusting (considering food products are involved). First, female weevils lay eggs on the surface of a grain, usually corn, rice, wheat, beans or peas.

"When the larva hatches from the egg it will crawl over the grain until it finds a suitable opening and then burrow into the middle of the grain," says Terminix entomologist Angela M. Tucker in an email.

"Once inside the grain, the larva will feed on the inside, develop and pupate (similar to a butterfly cocoon and not made of silk). The adult will emerge from the pupa stage, exit the grain, look for an adult of the opposite sex and the process starts again."

Now for the million-dollar question: Are weevils dangerous to humans? Fortunately, the answer is no. "They are not known for carrying pathogens which can result in illness," says Tucker.

Even if you use products laden with weevil eggs, feces, or molted skins, they won't hurt you. "The cooking process takes care of any food-borne illness risk but most people will throw out infested items," says Hottel.

The first step is throwing out the dry pantry products that they favor. Weevil larvae and eggs are super-tiny and usually hidden inside the grains, so don't try to sift through and remove adult weevils. You'll definitely miss some growing young weevils, and the cycle will perpetuate. Next, Lofquist says to thoroughly clean the pantry area, then store weevil-preferred foods in pest-proof containers. He suggests glass jars with tight-fitting lids.

Tucker cautions against relying solely on a bug spray to kill weevils. "There are products which are labeled for application to cabinets. I would not recommend using a residual liquid application as the adults can be physically removed and the immature stages will not be targeted as they are not moving in the cabinet space."

She adds that it's important to inspect product packaging for signs of damage, such as holes, tears and webbing. Use your grain products sooner, rather than later, and store them in the refrigerator or freezer for best results.

Sometimes, weevils can extend their reign of terror outside the pantry. "Weevils are especially long lived in their adult stage so it is common to see them wandering around the house for several months after the proper steps have been taken," Lofquist explains. "A vacuum cleaner is the best way to deal with these wayward adults."

If they persist, turn to the professionals. "Contacting a pest management professional can give homeowners peace of mind and confidence," Hottel says. "A technician will be able to identify the type of weevil present and create a specific treatment plan to rid the home of weevils."

This article was updated in conjunction with AI technology, then fact-checked and edited by a HowStuffWorks editor.