How to Prevent And Eradicate Flour Weevils And Mites


I finally decided to try a recipe since I had the extra time to stay at home. I grabbed the new bag of flour that’s been sitting on the corner shelf for more than a week and got an unpleasant surprise.

Lo and behold, when I opened the bag of flour, I saw flour weevils squirming in the white powdery contents. At times like this, you may wonder whether you should throw the whole thing out, or can you still use it?

A Flour Weevil is sluggish beetle that will feed and breed on flour.  Freezing the flour for seven days will eradicate weevils and their eggs.  Storing flour in airtight and hard-cased containers will prevent an infestation from Weevils and Mites.

If you find yourself in the same situation of opening a bag of flour with weevils, there’s no need to panic. This happens a lot in many households and is considered a common occurrence.

But you can avoid this from getting out of hand and preventing any infestation that will affect the rest of your dry goods in the pantry.

What is a Flour Weevil? 

With so many bugs crawling out of your pantry, how can you identify if the ones you see in the cupboard are flour weevils?

Do they come from the flour or another cardboard packed item in the pantry? 

At this point,  trying to analyze how the weevil came into the house is a futile effort.  It could have arrived with the cardboard boxes of pasta or cereal, or it could have been in the bag of flour all along.

A flour weevil is a beetle and called an insect pest because it can damage crops or stored flour.

The flour weevil is under the family of seed, grain, or maize weevils that have a short lifespan but can actively lay eggs in their year of life.

They thrive in dark, warm, and humid conditions but cannot survive in frozen cold temperatures. 

Weevils enjoy a diet of household products like flour, cornstarch, cake mixes, pancake mixes, cereals, and powdered milk. They are internal feeders and will thrive on its breeding ground, and will scrounge for powder, dust, or broken kernels on the surface.

The spill that happens when we grab the bag of flour or the bag left unopened is a sure invitation for the weevil or dust mite to flock to the pantry and begin its destructive purpose.

Preventing the weevil from getting into the pantry and other items has now become a battle of totally eradicating the insects and keeping them out of the pantry. 

What do Weevils Eat? 

There are many kinds of weevils, but home and garden species have three categories.  The maize or grain weevils eat dry products in the house.  

The second is the fruit and nut weevils that get their food from the gardens and orchards.  The last is the root weevils feed on the root of a strawberry, raspberry, evergreens, and many other plants.  

Maize or Seed Weevils enjoy a diet of household products like flour, cornstarch, cake mixes, pancake mixes, cereals, and powdered milk

This is the bug that you most likely have in your pantry.  They stay clear of whole wheat or whole grain, but they will scrounge for the powder, dust, or broken kernels left on the surface. 

Do Weevils Fly?

Both the maize and rice weevil are capable of flying. The red flour beetle is a ready flier and actively drawn to light. The red palm weevil can fly more than half a mile a day to feed or mate. Because of their tiny size, you won’t see them but they get around and land in the ideal place for their food source and to lay their eggs.

How About Those Tiny Bugs in Flour?

Aside from the flour weevil, the other bug present in flour is the grain mites.

They coexist with the weevil in the same breeding and feeding ground. Like the weevil, they live in flours, grains, and cereals stored in a dark and humid area in the house. 

The bugs present in flour are two different insect pests. The flour weevil and the flour mites have similar habits but look very different. They are both insect pests that eat into your flour and leave a sticky substance when the infestation has started.

Weevils and Mites seem to prefer cooking flour with high amounts of wheat at room temperature and lay eggs within the eight weeks of experimental observation.

They attack every dried food except whole wheat flour, which they tend to avoid like the plague. 

Difference Between a Weevil and a Mite

Flour mites are tiny insects that have white bodies with brown legs. They are almost invisible to the naked eye. Mites spread fungal spores and cause molds that make it a high allergen. 

You can get an allergic reaction ranging from itchy skin to respiratory problems such as difficulty in breathing or swelling of the throat.

Flour weevils are more visible with their less than 10mm body size and their dark brown color.  Weevils do not bring any allergies to humans but are destructive to plants and grains.  The worse damage they do is give an unpleasant taste when adult weevils die.

Are Weevils and Mites Harmful to Eat?

Thinking about accidentally ingesting a weevil brings a cringing experience for any homemaker or kitchen crew member.  It’s something you want to avoid to happen on your watch, much less accept that the people you want to keep healthy have eaten it.  

Weevils or Mites do not bite, sting, or poison human beings.  Except for mites that release a fungal spore that causes an allergic reaction to humans, the most damage it can do.  

Mites give out fungal spores and cause us an allergic reaction.  A person starts to feel an itch on the arms or face, swelling in the eyes, or difficulty in breathing, which are signs of mite reaction.

Digested Weevils do not have any adverse effects. If you unknowingly baked a batch of flour then discovered weevils at the bottom of the box, take it in stride.  You can think that both adults and larvae got baked along with the cookie. 

Flour Weevils and flour mites are simply pests you want to crush and terminate, not have seen them crawl in the white powdered flour you are about to use for a cookie or cake.   

Weevils are visible compared to mites that tend to look like sand.  Here are some reminders that you can keep in mind before you go through with baking or cooking.

How Do Weevils Get Into Flour?

Do you wonder how these tiny bugs get into the flour? There are many ways a weevil could have gotten into the bag of flour, but we’ll focus on their migrating behavior to understand the weevil’s movements.

Flour weevils begin their journey with the female beetle depositing the eggs into the crevices of food packages.

When the larvae hatch, they feed on the flour product. Within a month, the larvae or wormlike creatures develop into adults and live for 1-3 years, depending on the humidity conditions. 

The flour mills ensure the strict practice of food safety and sanitation standards, as well as control of pests. While they try their best to keep any insects out of production, there will still be some sneaky critters that can get through.

If the female weevil chooses to lay eggs in a box of flour in the packaging area, then the cycle begins for the larvae hiding out in the flour.

A few weeks have passed, and the flour is transported and sold on the grocery shelves. When it’s finally time for you to buy a bag of flour, another few weeks have passed.  

At this point, some larvae have turned into adults while others have lain more eggs in the same bag of flour.

How To Tell If Flour Has Weevils or Mites

  1. Before using the flour, you can place it on a wire strainer to see the presence of squirming weevils. The mites are harder to spot, but you will see white movements in the flour. They tend to look like sand in a background of white powder.
  1. Place flour evenly on a flat and even tray. Inspect the flour after 15 minutes and see if the tray or plate has some uneven portions. If you see a small lump grouping of flour, which is from the movement of a mite or a tiny weevil. 
  1. Try rubbing your fingers with flour and check for a smell. This is a bit tricky because of the differing scent. When mites are crushed in your fingers, it will smell like a minty odor, while weevils have an unpleasant odor.
  1. Watch out for a slimy or sticky feel to the flour that should always be dry. This means there has been an infestation with some carcasses or adult weevils that have died. There is also a strong possibility that larvae are ready to hatch.
  1. Examine the glue strip closely on the lid of cardboard boxes that contains flour or dry goods. You may see some insects stuck in the glue strip that attempted to get into the box.  
  1. Using a strip of scotch tape, apply the tape on the surface and edge of the shelf. The flour or dry goods will have bugs gathered around. Aside from the powder residue, you will likely see some white insect trapped in the tape. 
  1. Check out the cardboard containers of dry goods or plastic bag casing for any holes. If you find any, chances are, the weevils have gained entry into your flour, or cereal, or oatmeal.  
  1. In times of doubt, bring out the flour in sunlight, and you will see the weevil and mites crawl out of the flour. They do not like direct sunlight or heat but prefer dark, shaded, and humid places.

Seven Ways To Prevent Weevils in Flour

Preventing Weevils in Flour from entering the home is all about being aware of the weevil’s behavior and taking practical steps to avoid breeding in flour and affect the other items in the pantry. Simple steps to follow for a weevil-free and mite-free pantry.

It’s imperative to recognize the potential damage and harm a bag of flour can bring into the home.

Though unintentional, prevention is always better than trying to solve the problem. But the suggestions below are practical steps to prevent Weevils in Flour.

You can always improvise, but the easy guide is listed below for you to decide which steps fit your lifestyle.

Buy smaller packs of flour instead of the big bags

A recipe of five persons will need a few cups of flour.  Buying a big bag that will sit in the pantry for a few days or weeks can cause it to get rancid. 

Smaller packs will eliminate the chance of weevils and mites to breed in the unused flour that’s sitting in the pantry. 

Keep Flour In Freezer For 5-7 Days To Kill Weevils

Transfer the newly bought flour to a freezer bag and keep it in the freezer for five to seven days to kill any adult weevils and their eggs.

These insects cannot survive in a cold environment as they only thrive in warm and humid temperatures. This may be a tedious process when you arrive from the grocery and deal with frozen and fresh items.

But if you’ve conditioned your mind that you need to do this to avoid a bigger problem, then it is part of your after-grocery routine to do chores.

Store Flour In Airtight Containers

Transfer the flour into airtight containers such as glass, metal, or sturdy plastic cases. Weevils have elongated snouts that can bite through cardboard boxes and plastic bags of packed flour.

By transferring the items in hard-body containers, you protect the contents from being disturbed by the pests but also prevent them from laying their eggs.

Related Post: Best Leak-Proof Food Storage Containers

Add Bay Leaf Or Garlic to Repel Flour Weevils

Add a piece of fresh bay leaf in the airtight flour container because weevils do not like the smell of bay leaf.

You will have to replace the bay leaf in the airtight container once it dries up on the remaining flour.  This practice is an old farmer’s trick to keep the bugs away from grains.

Add a clove of garlic in the airtight container as garlic is a potent spice that weevils cannot tolerate. The downside of adding garlic is the taste and smell that lingers in the flour and has a garlicky flavor.

The advantage is you have a natural tasting garlic flour and can use this for recipes on coating chicken wings or garlic bread.

Keep Tea Tree Oil Next to Dry Goods

Using a cotton ball, you can apply some essential oil of tea tree and leave it on the shelf of flour and dry goods since weevils and mites cannot stand the scent. 

You’ll have to keep changing this whenever the cotton ball dries out or when you no longer smell anything.

Use Eucalyptus, Neem, and Pine Essential Oils

Use a natural antibacterial, antiviral, and antifungal Weevil Spray of water mixed with essential oils such as Eucalyptus, Neem, Pine needles. 

Spray in the dry goods area with sealed containers. You’ll not only enjoy the pleasant smell of these essential oils but will benefit from the antibacterial and anti-allergy properties of these natural cold-pressed oils.

Periodically Check Flour For Insect Presence

Continuously check every week for any new presence of weevil or mites every time you bring in a new bag of dry goods, in particular flour.

You might as well accept that this is an ongoing process that you have to repeat every time you buy a new package of dry goods since weevils and mites like other products aside from flour. 

How to Get Rid of Weevils and Mites

As soon as you see a weevil or a flour mite, it’s time to get into action to get rid of it.  Procrastinating or worse, ignoring the problem can be a pending problem not only for your pantry goods but all over your house. 

But the problem doesn’t stop in your food or parts of your home. It affects the people living there, your family members, and their health. 

To eradicate the Weevils and mites requires a plan of action that ranges from home remedies to hiring professional pest control to prevent any infestation. 

Getting rid of weevils and mites at an early stage is a preventive measure on the infestation. Left attended, it becomes a huge problem that will continue to grow.

Why?

As long as the pests are left to breed, they will keep laying eggs while the cycle goes on.

Find the source of weevils and mites

This is the first step if you want to get down to eradicating those pesky insects.

Start with the cartons of flour, cereals, oats, rice, quinoa, bran, crackers, spices, herbs, dried pasta, dried fruit, chocolate, dried peas, and beans.

These items in your cupboard or pantry are the favorite dry foods that weevils and mites like to feed and breed on.

Discard any food item that has weevils

When you see tiny insects in the contents of flour or oats, that is the signal of weevil presence. There are adults and larvae about to hatch.

You might hesitate to throw out the unused portion and think that it wasted money or wasted food.

But consider that these items may have carcass or feces, or larvae about to hatch in the same flour, and that should take out any question of throwing it out the garbage pronto.

Block weevils from getting out of infested flour

You have to seal the trash bag to avoid any bugs from crawling out of the dry goods and make their way back to your house or your neighbors.

Sanitize by boiling glass containers or wash well plastic containers with a little quantity of bleach mixed with water to kill any bacterial build-up or molds.

Buy weevil traps with pheromones

Weevil traps with pheromones are known to attract weevils, mites, and pantry moths. It looks like flypaper with a sticky space that traps pantry pests.

The set-up traps will stop the adult weevil from traveling into other boxes of your pantry and laying its eggs on other breeding grounds.

Use DIY Weevil and Mite Spray

What is your reaction when you see bugs at home? 

You would likely get to a directory or scroll through your smartphone for a pest control service.  You would think of calling a friend who knows the number of a neighborhood pest control service or home pest service.

But before you grab the phone, there are easy homemade solutions you can mix that are safe, non-toxic, and not harmful to the family.  It’s a choice between commercially made or homemade. 

Should you use the commercial insecticide made of toxic chemicals that have a long-term effect on our health and may poison pets, or the other option is to use a natural solution that is safe and non-toxic for humans and pets.

Following are two easy to make flour weevil sprays. They provide effective deterrents to keep the insects away from the whole area and pleasant scents for your family members.

Essential Oil and Water

Use two teaspoons of Essential Oils such as Tea Tree, Peppermint, Neem, Eucalyptus.

Then add 2 cups of water and transfer to a dark-colored sprayer bottle. Essential oils are cold-pressed natural oils that need only a few drops to get the scent.

This solution acts as a double purpose to repel the weevils and mites, as well as give a pleasant scent lingering in the home. 

Citrus Spray

Use the squeezed lemon or orange or lime peelings or used fruit rind that you can soak in water for two days.

Then drain before transferring to a spray bottle made of glass.

This solution is not as potent as the essential oil mixture but acts like a repellent for weevils, mites, and even ats.

Use this solution to spray the shelf or cupboard, or even the doors of the pantry.

Vacuum the shelves, crevices, and cracks in pantry

With a mop dipped in a mixture of water and a little bleach, clean the floors of any powder residue.

By eliminating any powder that has accidentally spilled out or an unnoticed hole done by a scavenging insect, a pantry area is a clean place that any insect will keep its distance.

Keep dry foods in airtight hard-body containers

Keep dry food in containers made of glass, hard plastic, or aluminum that weevils cannot bite through an opening like cardboard boxes and plastic bags.

The pasta noodles, the rice grains, the oatmeal, and the cereal all have to be transferred to hard-body containers before the weevils detect a carton that they can chew their way inside.

This requires an acceptance of added chore requirements for after-grocery work. 

Use Diatomaceous Earth and/or Tannic Acid

These natural fossilized diatoms of hard-shelled algae stick to the body of flour weevil or flour mite and have the effect of dehydrating the insect.

You can leave it on the shelf of dry goods, and while it may be a bit messy, at least it is not harmful to pets or anyone in the house.

The tannic acid in powder form is a preparation of plant tannins composed of gallic acid with glucose.

Tannic Acid powder mixed with benzyl alcohol becomes a plant-based insecticide. This solution will probably be a strong spray for the adult weevil and mites. 

Contact a pest control professional

With a pest control professional you can discuss your concerns about eradicating the weevils and mites.

Pest control will have choices of pesticides they offer, from the very strongest to the minimum toxicity.

You’ll have to agree to a scheduled plan from aggressive to a quarterly or bi-monthly visit from them. Point out that you will opt for a non-toxic and non-harmful solution used near your food area.

How Do Weevils Invade the Home

Aside from the flour weevil, there are the garden weevils that live outdoors and eat the leaves of plants, trees, and shrubs. 

They go on their merry way until winter where they seek shelter.  The species of weevil able to fly, are attracted to the light, will hang out in the door or window of the house.

Another way is to creep their way through broken screens, attic vents, or crawlspace vents.  An obvious entry point is the cracked part of a window or a damaged door because of weather stripping.

Home weevils looking for heated insulation will spend winter behind the walls.  But some will crawl in a pipe or crack in a baseboard. 

They can even pass through a light fixture to crawl down and attack the fruits on the table. If not, the weevil will wait for a vegetable that will be cleaned and sliced, and near a chopping board.

These weevils can go anywhere in the house, set up in any room that has windows. They are crawling on the walls, ceilings, or window sills then drop to the floor. 

The outdoor weevil living in the warm temperature of the house, makes them want to go out. 

This explains why the window is their favorite hangout area.

Photo credit: ©canva.com/TRAVELARIUM, ©canva.com/Tetiana Kolubai, Clemson University – USDA Cooperative Extension Slide Series (Bugwood.org)

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