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What are Flour Beetles?

Susan Grindstaff
Susan Grindstaff

Flour beetles, also referred to as flour weevils, are beetles that commonly lay their eggs in flour, rice, and other milled grains. They are tiny insects, averaging only .125 of an inch (3.17 mm) in length. These bugs are thick bodied and brownish red in color, and are one of the most frequent pests that plague household cupboards.

Female flour beetles usually lay more than 500 eggs during their life cycle, which usually lasts about a year. The eggs hatch into larvae that resemble tiny whitish gray worms. It takes a couple of months for the larvae to become adult beetles.

A person sifting flour.
A person sifting flour.

Though many types of beetles have been known to infest grain products, two species in particular are the most commonly found in household cupboards. These are the flour beetle and the red flour beetle. These two types of flour beetles are almost identical except for the shape of their antennae. The flour beetle has antennae that curve inward toward each other, while the red flour beetle’s antennae have very little curvature at all.


Many people believe that a flour beetle infestation is caused by unsanitary conditions, however, this is often not the case. In many instances, products purchased at groceries are already contaminated with weevils before they are even opened. Contamination of grains can occur in any stage of the milling process, and even if flour beetles are found during processing, it is often near impossible to get rid of the eggs. This is because the eggs are so miniscule they cannot easily be distinguished from the grains.

Often referred to as flour weevils, flour beetles lay eggs in flour, rice, and other grain products.
Often referred to as flour weevils, flour beetles lay eggs in flour, rice, and other grain products.

There are some obvious ways to help ensure that grains purchased at grocery stores do not contain flour beetles. Shoppers should avoid purchasing products with packaging that is torn or damaged. If the glued tabs on the edges of boxes seem loose, these packages should also be avoided. It may also be a good idea to check the "sell by" date on the packages. The longer a package stays on shelves, the more likely it is to become infested with pests.

Once milled products are purchased, home storage can play an important role in keeping the grains safe from beetle infestation. Flours or grains that come in paper bags should be put into containers that can be sealed. This includes containers made of glass or tin, as long as they have openings that can be tightly sealed against pests. Many people prefer the use of plastic vacuum type seals, as they also help preserve food freshness while protecting the foods from infestation.

Frequently Asked Questions

What exactly are flour beetles?

Flour beetles are small, reddish-brown insects that belong to the family Tenebrionidae. They are commonly found infesting stored grain products and are considered pests in both homes and commercial facilities. There are two primary species: the red flour beetle and the confused flour beetle, which are often found in flour, rice, and other dried foods.

How do flour beetles get into our food?

Flour beetles can enter homes through purchased infested food products or by slipping through tiny cracks and openings. They are attracted to a variety of dried, starchy foods and can lay eggs directly in food products. Once inside, they can quickly multiply, leading to a significant infestation if not promptly addressed.

Are flour beetles harmful to humans?

While flour beetles are not known to transmit diseases, their presence in food can cause contamination. They can spoil food products by leaving behind shed skins, feces, and dead individuals, which can lead to an unpleasant odor and taste. Consuming infested food is not recommended due to potential allergic reactions and the degradation of nutritional value.

What are the signs of a flour beetle infestation?

Signs of a flour beetle infestation include the presence of small, crawling beetles in pantry areas or in food products, as well as finding larvae, pupae, or shed skins. Infested food may also clump together due to the secretions from the beetles, and there may be a noticeable musty or moldy smell.

How can we prevent flour beetle infestations?

To prevent flour beetle infestations, store food in airtight containers, regularly clean pantry shelves, and discard any infested products. Purchasing food in smaller quantities to ensure quick turnover and inspecting food items before bringing them into your home can also help reduce the risk of bringing these pests inside.

What are the most effective methods to control flour beetles?

Effective control of flour beetles involves a combination of sanitation, proper storage, and, if necessary, chemical treatments. Infested food should be discarded, and the storage area thoroughly cleaned. Pesticides should be used as a last resort and applied according to label instructions. Consulting with a pest management professional may be beneficial for severe infestations.

Discussion Comments


I *hate* flour beetles, or weevils, or whatever you want to call them! They're nasty!

The one time I found them in my flour, I also found them in my cornmeal and in my pancake mix and baking mix. Had to throw it *all* out and scrub my cabinets.

The other thing I've found is that they tend to dislike flour stored in metal, whether it's a metal canister or a metal cabinet. They like wooden cabinets. I don't know why that is, but since I've had a house with metal kitchen cabinets, I have yet to see a weevil in my flour. But I'll keep it in the fridge, just in case one decides to show up. Don't want to give them any help in setting up housekeeping!


There's an easy fix for this: put your flour into a zip-top bag (still in the flour bag) and keep it in the fridge or freezer. The little devils can't breed in the cold.

If you want to know if your flour has any weevils in it, get about a third of a cup from the middle of the bag and stir it into very warm water. It sounds gross, but if there are weevils in it, they will die and float to the top of the liquid. If you find weevils in your flour, if it's a new bag, take it back to the grocery store. If not, throw it away outside and scrub out your cabinets. Store new flour in the fridge. That's the best way to get rid of them: keep them from breeding and hatching in the first place!

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    • A person sifting flour.
      A person sifting flour.
    • Flour.
      By: airborne77
    • Often referred to as flour weevils, flour beetles lay eggs in flour, rice, and other grain products.
      By: food pictures studio
      Often referred to as flour weevils, flour beetles lay eggs in flour, rice, and other grain products.