What Are These Bugs Doing in My Dry Goods and How Do I Get Rid of Them?
Learn why the weevil is the scourge of every kitchen.
So you followed pandemic advice and outfitted your pantry for the long haul. Or maybe you belong to a warehouse club, have a big family to feed, or appreciate BOGO deals. At any rate, you stocked up on flour for baking. You purchased a good amount of pasta or rice, figuring that starches never really go bad anyway. Then you might have also invested in big-bulk cereals, pancake mixes, oatmeal, and instant mashed potatoes.
And now, you have 8- to 10-millimeter-long, black- or brown-bodied bugs with elongated, bent snouts crawling through all of it. Elsewhere, you're finding piles of them in the corners of your cabinets, some dead, some barely alive. They seem to be everywhere, even in unopened boxes of mac-and-cheese. What are they? How did they get there? And most importantly, how can you get rid of them?
Meet the Weevil
Get to know rice and maize weevils, two of more than 60,000 species of herbivorous beetle. They're the scourge of pantries everywhere. Entomologists with Ehrlich Pest Control say that, in particular, "rice weevils have been reported infesting rye, barley, buckwheat, table beans, stored cotton, grapes, cashew nuts, cereals, wheat products, pasta, and bird seeds."
Meanwhile, Dave Lofquist, technical training manager for Arrow Exterminators, notes that adults of both kinds of weevils "can live for many months and are capable of wandering a good distance from the original infested item. Their chewing mouthparts can penetrate plastic and cardboard packaging, which will enable them to spread the infestation."
In other words, as pests, weevils are really high up there on the scale, given that they don't seem to discriminate in their food sources much and easily burrow into closed packaging—or escape from it. In fact, Lofquist says, "Some will also damage vegetable gardens and ornamental plants."
Scott Svenheim, director of training services for Truly Nolen Pest Control, says weevils also eat "furniture, clothing and other fabrics, and decorative items." This is why he recommends complete eradication of any infested food products plus a solid cleaning and vacuuming of cupboards.
How They Arrive
According to all the aforementioned experts, weevils frequently enter your home in the product itself, some of which is imported from other countries in foods such as rice, sunflower seeds, and feed corn. And, Lofquist emphasizes, weevils "are pests of whole grain. The egg, larvae, and pupal stages all occur within the grain which makes detection difficult."
Yes, that means the rice weevil is small enough to burrow inside a single grain of rice, where it's often invisible to humans—or machines, of course—sifting and packaging a lot of product at one time. Bug Lord's Wesley Wheeler confirms, "While this may be tough to hear, weevils are not after the rice simply for a food source like most pests; weevils actually lay their eggs inside a grain of rice. The larvae then hatch and eventually eat their way out of the grain of rice and begin the mating cycle again." A single adult female can lay up to 300 eggs during its lifespan, which ranges from 32 days to six months.
Unopened, sealed bags of products that are already infested are usually like that "due to a lack of quality control," Wheeler says. If you purchase and open such an item, discard it immediately to an outdoor trash can.
How to Control the Infestation
The mass-market food chain is not the only way weevils can get into your home. "Rodents and other wildlife may also bring seeds and nuts into a home that could become infested with weevils or other potential pantry pests," Lofquist says. That means the weevils you throw out could become your neighbors' weevils if you aren't careful and, for example, raccoons dump your garbage.
The pest experts are all unanimous about using the freezing method—wrapping the product in a heavy duty plastic bag and sticking it in the freezer for a several days—whenever you bring in a potential risky source of weevils, such as rice or birdseed. Fantastic Pest Control's Jordan Foster says, "The rule of thumb is that you should freeze packets of flour, oats, cookies, cornmeal, and spices for four days after purchase."
They also agree about using barrier perimeter methods to control potential weevil infestations. In addition, according to Wheeler, you should "seal any cracks and crevices near foundations and windows, and put all grains, pasta, oatmeal, cereal, [and] breadcrumbs, in tight-sealing containers."
Should it be too late, however, don't listen to advice on the internet, which may tell you it's safe to sift through your grains, chips, crackers, and pasta, discard the visible bugs, and still eat the products. While they generally don't harm you, Foster says, "Weevils are much like mosquitoes; they can sting but seldom cause death. But when they do, it's usually from an allergic reaction or ingestion of their eggs."
Regardless, you won't get rid of them unless you dispose of both the adults, the eggs—which are, as mentioned, actually inside the material—and the food source.
But the last little piece of advice is something that no warehouse shopper wants to hear. "To prevent the appearance of weevils in your pantry, consider storing small amounts of grain at any given time, just the right amount that you would estimate to consume for a certain period," says Thomas Jepsen, founder of Passion Plans, an online service connecting architects and home builders. "Weevils are tricky. They can stay inside grains for a while before literally eating their way out into the stored grain. Thus they appear to infiltrate containers made of glass."
How to Prevent Weevils
If you just can't bring yourself to break the bulk-buying habit, consider Jepsen's other solutions, which he says "are a mix of logical architecture and interior design." First, find and fix—or at least be aware of—what he calls "hidden crevices inside your pantry." That's where weevils can find and feed on errant grains that have fallen. Just one grain of rice can make your kitchen susceptible to infestation.
Second, ascertain the average temperature of your kitchen. "Despite seeming invulnerable, weevils aren't fans of extreme temperatures," he says. This is why a relatively low oven temperature can destroy them.
Finally, take note of how humid your environment feels and take measures to reduce moisture. While weevils don't like heat, they do like tropical climates. "Think of how this factors into your pest control," Jepsen, who frequently counsels first-time homebuyers, says.
On that note, he also offers a reminder: "Never, ever consider pesticides in the kitchen."
To that end, depending on how bad your weevil problem is, throwing out all their food sources and vacuuming the closets, shelves, and baseboards might not be enough. "Weevils are persistent," say entomologists at Ehrlich Pest Control. "If you are concerned about an infestation, it may be important to call a pest management professional to inspect the area, ensure that all of the weevils and eggs have been removed, and develop a plan to ensure the weevils do not re-infest the areas."
But you can also always try some natural remedies that you might have on hand. "Cloves and bay leaves can act as natural repellents to weevils. Place a few bay leaves around your pantry and kitchen to ward off these pests, and position several [fresh] cloves of garlic near your food storage supplies," Foster says. "Also, mix one tablespoon of white vinegar with one cup of water. This solution will keep bugs out of your pantry and basement spaces for up to six months."