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Grain Weevils: How to Get Rid of the Pest

Grain Weevil: A Close-Up of a Grain Weevil
Reddish to dark brown and up to 5 millimeters long, the globally widespread grain weevil has a sharp mouthpart. Photo: Getty Images
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October 17, 2022, 1:11 pm | Read time: 3 minutes

Once the grain weevil has settled in, it’s hard to get rid of. myHOMEBOOK explains how to evict the unwanted guest.

A feared pest found worldwide: The brownish snout beetle has sharp mouthparts that bite holes in grain husks. Female grain weevils lay their eggs in the nibbled grain. The offspring consume almost the entire grain kernel until pupation, causing significant damage.

Can a grain weevil cause damage in my home?

Grain weevils often become a serious problem in grain silos. The infestation is not immediately noticeable. From the grain storage, it’s just a short trip to the kitchen or pantry. Thus, the beetles also spread in homes, as experts from the German Environment Agency write. Entry points include grain products and spoiled pet food.

Are grain weevils harmful to humans?

Grain weevils infest many types of grain. Rye, wheat, barley, or oats are a feast for the pests. The beetles also target rice, legumes, or pasta.

According to the German Environment Agency, food contaminated by grain weevils is harmful to health. The kernels gnawed by larvae may contain excrement. As a result, the food is colonized by bacteria, mites, and mold. The grain then smells musty and must be discarded.

Also interesting: 7 home remedies to effectively combat aphids

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Can I protect myself from grain weevils?

Since the beetles cannot fly, an infestation is initially difficult to detect. Those who store large quantities of grain should regularly check for infestation. “Depending on environmental and food conditions, grain weevils can live between six months and two and a half years,” write experts from the German Environment Agency.

To make the environment as uncomfortable as possible for the pests, you should heat things up. Their lifespan is shorter in heat and high humidity than at a low temperature of around 10 degrees Celsius.

You can also prevent an infestation by transferring open food into sealable containers and storing them as cool as possible. This effectively protects grain products from the pesky grain weevils. You should regularly clean pantry cabinets.

By the way: A cause of grain weevil infestation could be bird nests located on or even in the house. According to the German Environment Agency, such nests should be removed. Infested food should also be stored in the freezer at minus 18 degrees Celsius for three days. The pests perish from the cold.

Also worth reading: Is milk a natural miracle weapon against aphids?

How do I combat grain weevils?

Dispose of infested food immediately in the household trash. Use the parasitic wasp Lariophagus distinguendus to biologically tackle the pest. These beneficial insects can be purchased from specialty stores or ordered online. myHOMEBOOK explains here how to use them.

Commercial insecticides, however, are of little help against a grain weevil infestation. The insects show a pronounced resistance to chemical control agents. In the case of a very severe infestation, you should contact a pest control professional.

This article is a machine translation of the original German version of MYHOMEBOOK and has been reviewed for accuracy and quality by a native speaker. For feedback, please contact us at info@myhomebook.de.

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