There are high chances your flour or rice is infested by flour-eating bugs if it has clumps and if it tastes sweet.
Many types of bugs are known for favoring flour and rice over other foods.
Dry flour is the main food for multiple bugs such as the Indian Meal Moth or the Biscuit Beetle.
These bugs are among those that can cause health problems through infested food.
Gastrointestinal problems are common with bug-infested flour.
A reduced market value is also a result of bug invasions in facilities that process flour.
How Do Bugs Get Into Flour and Rice?
Various species of bugs can be found in flour and rice. There are a few common signs flour might be infested with bugs such as the following.
- Old flour
- Poor sanitation
- Nearby food infestation
But bugs can get even in fresh flour and in places with good sanitation at times. Here’s how they do it.
Infestation from other infested foods
The most common route for bugs to your flour is by infested food. You can buy bug-infested dry foods from stores.
Bugs that eat dry foods of a vegetable nature eat flour.
They can infest all other dry foods in the pantry.
You can also buy flour that’s already infested from stores.
Some bugs fly into your flour. They can also spread by flying.
Some flour-eating weevils are known for flying and spreading infestation either to other packs of flour or throughout flour mills or flour-processing facilities.
Some flour bugs cannot fly. They crawl and make their way to flour as any other type of bug.
Eating through packaging
A good percentage of flour bugs can eat plastic and cardboard.
This means they can eat through plastic packaging or plastic bags flour is stored in at home.
They can chew cardboard in a matter of hours as many of these bugs have snouts or elongated mouthparts adapted for chewing.
17 Types of Bugs in Flour and Rice
The following bugs are the most common in flour and rice. Some have a clear origin and most have spread around the world.
1. Indian Meal Moths
Indian Meal moths (Plodia interpunctella) are large insects that feed on flour. They grow up to 10mm and have long wings that extend up to 20mm.
These long wingspan bugs are known for eating flour.
They also eat all types of dry foods made from vegetable sources such as nuts, bread, pasta, and rice.
Other dry food also attracts these bugs. Dry dog food and dry fruits are also go-to meals for the species.
Indian Meal Moths are a common bug in flour.
However, the common nature of the species doesn’t make it easy to eliminate. This species also eats through plastic and cardboard.
This means many pantries can be very infested long before you notice them.
The bugs are known for their negative impact on the packaging which they don’t eat but which they can cross.
Even plastic bag-packaged flour can be affected by the species.
There aren’t too many methods to get rid of these bugs once they settle in flour.
You can prevent them with certain measures, on the other hand.
One of these measures is using violet lights.
Alternatively, you can also consider using various types of traps.
Sticky traps tend to work well against these bugs.
2. Angoumois Grain Moths
Angoumois Grain Moths (Sitotroga cerealella) infest all types of stored grains such as flour, rice, rye, and seeds.
The species is highly common in China and India. Its exact origin place isn’t known.
This bug in flours is very dangerous as it can affect it in different ways. It infests flour making it unusable but it also spreads quickly with habits different from those of other bugs in flours.
For example, the Angoumois Grain Moth doesn’t feed as an adult. Only the larvae of this species feed.
Adults only reproduce without having much interest in eating flour or other dry grains.
The larvae of the species are known for their high impact on grains and seeds.
Most affected seeds cannot germinate. Flour affected by these larvae cannot be sold and needs to be discarded.
If your pantry is infested, the larvae can spread to almost any type of vegetable-origin dry food and even to bagged cereal.
Eliminating this species from the pantry is difficult and it requires taking precautionary measures.
Reducing humidity levels is one of the recommended actions against it.
Cleaning all storage bags and boxes for flour routinely is wise as well.
You also need to bag and discard all affected flour as soon as discovered.
3. Flour Mites
Flour mites (Acarus siro) are a common flour bug that bites. These mites can bite people at times and it’s best to detect them early.
Flour mites grow up to a size of 0.43 inches.
They have a faded gray color and the ability to fly.
Bugs of this genus make it into flour by infested flour you buy in stores or by improperly storing flour at home.
Flour infested by Flour mites and their eggs tends to have a sweeter taste. It’s also stickier than regular flour.
Health risks have been associated with eating flour infested with Flour mites both in humans and in animals.
Baking goods with infested flour can cause diarrhea as well as other gastrointestinal problems.
Flour mites tend to thrive at home.
They might find it difficult to thrive in warehouses where flour is stored as predatory species soon control them.
Ants can sometimes eat or nest in flour. They are typically attracted to sugary foods.
There’s a higher chance of seeing ants in flour after it’s infested with Flour mites.
It’s Flour mites that make flour taste sweeter and in turn, this attracts ants as well.
Ants can eat the flower or simply lay eggs in it. Unlike other bugs in flour, you can control ants easier.
Sealing all entry points is mandatory when it comes to ant invasions.
Ants cannot eat through plastic so storing flour in plastic bags is another method of keeping these insects out.
Some ants can also be interested in eating bugs in flour and they might not fully go away until you discard the flour altogether.
Ants also tend to infest other foods nearby as they aren’t tied to dry grains.
They can look for any type of fruit or unsealed food.
5. Granary Weevils
Granary weevils (Sitophilus granarius) are found all around the world.
These small bugs measure around 1/8” and are identified by their brown coloring and elongated mouthparts.
Common in areas with high humidity, these weevils can easily infest flour and other stored foods.
Their presence in flour typically signals their presence in other types of foods.
Like many bugs in flour, Granary weevils can also make it through plastic or cardboard. This makes these bugs a lot more dangerous for dry foods than others.
The damages these bugs can make are extensive to the extent they go after dried foods and even after dry flowers.
Reproduction rates are high for this species.
A female Granary weevil can lay as many as 150 eggs in 7 months.
Eggs then hatch into worm-like cream color larvae which can be among the first signs of a Granary weevil infestation.
6. Rice Weevils
Rice weevils (Sitophilus oryzae) are similar to Granary weevils but with the ability to fly and are known for laying more eggs.
The female Rice weevil lays up to 300 eggs per year, twice as much as the female Granary weevil.
These bugs are also known for their dark brown body and elongated mouthparts.
You can distinguish Rice weevils from other weevils by the 4 orange spots on their wings.
These weevils lay eggs in individual grains out in nature. They are purely detrimental to growing grains and stored grains.
There are multiple methods to eliminate this species.
Freezing and heating infested food are among the tested methods to kill Rice weevils.
However, infested flour should be discarded as it can create gastrointestinal problems.
7. Maize Weevils
Found in tropical climates, Maize weevils (Sitophilus zeamais) are known for their high impact on stored grains and flour.
They also eat grains from crops.
These weevils have a dark color and they appear almost entirely black.
Maize Weevils grow from 2 to 5mm and can be distinguished by other very similar weevils in flours by their red spots.
Present in tropical climates, the Maize weevil often makes it into grain processing facilities undetected.
Most of their eggs are laid in grains and to find them often involves putting the grains in the water to see if they float.
Maize weevils can be prevented by using all types of traps and by frequent vacuuming.
The damage to the species can be high if left undisturbed.
Maize weevils are the flour-eating weevils with the highest multiplication rate.
Up to 400 eggs are laid by the female Maize weevil in a matter of up to 8 months which makes it a rapid spreader.
The damages are so high in stored grains that entire warehouses need to be emptied after the female has been discovered.
8. Red Flour Beetles
Red Flour Beetles (Tribolium castaneum) are a known bug in the pantry. They infest many stored foods such as flour, beans, pasta, and even dry species
The color of the bug is red-brown which differentiates it from other bugs such as weevils.
Growing to a common size of up to 1/8”, the Red Flour Beetle has made it to the US from India.
This species is known to prefer warmer climates and it’s mostly found in the Southern states.
Preventive measures are similar to the preventive measures against other bugs that eat flour.
Discarding infested foods is required as well.
One of the areas where the Red Flour Beetles prove a bit more provocative to deal with is their long lifespan.
Unlike most other bugs that live up to 1 year, Red Flour Beetles survive on very little food for up to 3 years mating and infesting all areas of the house with food further from the pantry.
Thousands of eggs can be laid in this long lifespan creating serious infestation problems.
9. Confused Flour Beetles
Highly similar to the Red Flour Beetle, the Confused Flour Beetle (Tribolium confusum) is also red. It grows to a size of 3 to 6mm.
The antennae of the Confused Flour Beetle are shorter and the easiest method to differentiate it from other similar species in flour.
Confused Flour Beetles only infest stored flour and not kernels. This is why they are only seen in homes or food processing facilities rather than on crops.
These bugs are also known for infesting all other dried foods such as dry beans, dry fruit, and rice.
This species of flour beetle is mostly confused with the Red Flour Beetle which also inspires its name.
Killing the Confused Flour Beetle isn’t easy as the species has the resilience to cleaning products and temperature changes.
10. Cigarette Beetles
Cigarette beetles (Lasioderma serricorne) are some of the smallest bugs in flour.
These bugs grow to a maximum length of 2-3mm sometimes being difficult to spot.
Common in flour mills, Cigarette beetles get their name from the impact they have on dry tobacco leaves in cigarette manufacturing facilities.
Beetles of this genus are seldom tackled by insecticides as these have a
detrimental health effect in food manufacturing facilities.
Cigarette beetles are often dealt with by professionals as they’re a nuisance pest not affecting flour as adults.
Fumigation is used by professionals against them.
Other techniques that involve raising and maintaining warm temperatures in flour mills also prove successful against this species.
At home, this bug is dealt with by removing all infested items. Infested flour and infested dry food need to be discarded.
While it can now be seen all around the world, this bug is still most common in areas where tobacco is processed.
11. Drugstore Beetles
Drugstore beetles (Stegobium paniceum) are small brown bugs that often infest flour. These bugs grow up to a size of 3.5mm and can be distinguished from other flour-eating bugs by the shape of their antennae.
Drugstore beetles have serrated antennae which makes them unique-looking.
Bugs of this genus are sometimes difficult to tie to flour as they are known to eat almost anything they can find.
In theory, Drugstore beetles only eat drugs and medicine as their name implies.
But these bugs eat all types of food and even packaging. They can make their way through packaging to flour.
Cookies are also consumed by the bugs.
Non-baked products are infested as well. Drugstore beetles can even eat chocolate.
These beetles have been reported to eat almost any type of food they can find, this includes cardboard and paper packaging.
All infested foods and goods should be discarded.
While heat kills these bugs, they remain in the flour. This means infested flour needs to be placed in plastic bags and discarded.
12. Sawtoothed Grain Beetles
Sawtoothed Grain Beetles (Oryzaephilus surinamensis) infest all types of damaged grain, flour, tobacco, rice, cereal, and even dry meat.
These bugs are so prevalent they are the most common flour-infesting bug in many countries around the world.
While known for its preference for warm climates, the bug has been imported to countries all around the world.
These bugs are identified by their small body which grows to a maximum length between 2 and 3mm.
Brown uniform coloring and long antennae are also specific to the species.
These bugs make the most of cracks and crevices making their way into areas with stored dry food.
Sealing all cracks is recommended for areas with stored food to keep these bugs out.
13. Warehouse Beetles
Warehouse beetles (Trogoderma variable) have an oval shape. They are characterized by brown, black, and white coloring.
These colors are seen in the form of lines on its body.
Warehouse beetles grow to a size of around 1/8”.
These bugs are known for eating flour. They also eat all types of other foods such as beans, dried potato chips, cereals, and candy.
Eliminating Warehouse beetles is very difficult.
Like other bugs that eat flowers, Warehouse beetles tend to spread out through the building so they infest multiple rooms and multiple floors.
Eliminating them from kitchen cabinets or the pantry doesn’t equal completely getting rid of them.
These bugs can easily spread around the house or the premises.
Warehouse beetles are more common in flour processing facilities than in homes.
A combination of preventive methods such as traps is used by these facilities to keep the bugs out.
14. Foreign Grain Beetles
Foreign Grain Beetles (Ahasverus advena) are common in some US states.
These flour-eating bugs are most common at the end of August. The end of the summer and the beginning of the fall marks their most busy period of the year.
These bugs love warmth and heat.
But they tend to disappear in October as temperatures start to drop considerably.
Foreign Grain Beetles don’t bite but they can fly.
Their reduced size coupled with a dark brown color often makes people confuse them with flies.
Keeping these bugs out is a matter of sealing all entry points and checking the flour you bring into the house.
Since they can fly, these bugs can also easily spread around the house.
Removing all food sources might not be sufficient for these types of bugs.
In the absence of dry foods, these bugs will move on to mold, which might not be difficult to find in homes with high humidity.
15. Merchant Grain Beetles
Merchant Grain Beetles (Oryzaephilus mercator) are common in the US and Canada.
This species has a dark brown color and an average body size of 2.5mm. It creates damage by infesting foods in the house.
Identifying the species solely by the damage it does to food isn’t possible.
Even if it eats other foods except for flour it still has an eating pattern that makes it difficult to identify.
The bug can be found in all types of dry food, especially packaged dry food.
It eats through the packaging to get to the dry food where it can also reproduce at a very high rate.
Females of the species lay anywhere between 400 and 600 eggs within 7 months.
All bugs of this genus make their way to the house through the purchasing of infested foods.
All foods such as flour that are infested with Merchant Grain Beetles come from infested storage or infested stores.
16. Khapra Beetles
Khapra beetles (Trogoderma granarium) are common in the US. These bugs eat barley flour and other types of flour.
This bug is identified by its brown and black oval body. It has a black head and black legs.
Beetles of this genus grow up to 3mm as adults even if they are longer as larvae, growing up to 5mm.
Khapra beetles have one of the shortest lifespans of all bugs that eat flowers.
They live up to 10 days albeit many days within the 5th day in the absence of food.
17. Lesser Grain Beetle
The Lesser Grain beetle (Rhyzopertha dominica) has a red-brown color and it grows up to a size of 3.3mm.
Lesser Grain beetles affect all grains and flour storage facilities that aren’t properly protected in Australia and India.
These bugs also affect kernels eating and growing within grains.
Their damage is sometimes invisible at first given their reduced size.
A sweet flour aroma is normally tied to their presence.
Is It Safe to Eat Infested Flour?
Eating a small amount of infested flour should not cause any health problems.
Some bug traces are even approved by the US Food and Drug Administration.
However, eating too much-infested flour quickly leads to certain health concerns.
Food poisoning is possible when eating infested flour. Food poisoning is the biggest concern with infested flour. It can clear in 1 day or 7 days, depending on its severity.
This type of reaction is common when eating flour or baked goods made from infested flour that contains the following.
- Traces of bugs
All of these can cause food poisoning at some point for most people.
Food poisoning from infested flour can be avoided by routinely swapping old flour for new flour in the pantry and by keeping bugs out.
How to Get Rid of Bugs in Flour
Getting rid of bugs is not easy when it comes to flour bugs. Most of these bugs are small and difficult to spot.
Some of these bugs can even fake death and become immobile when you expose them becoming more difficult to see than moving bugs.
As a result, getting rid of flour bugs can be a long process.
Discard the flour
The first thing to do is to discard the flour if you find bugs, eggs, or larvae in it. This should be done in a particular manner in which these bugs cannot escape as many can fly.
- Place the infested flour in a sealed plastic bag
- Discard the flour
- Clean the infected area
Discarding the flour in a sealed bag is important as they can escape otherwise.
Infested flour also means there are high chances of other dry foods being infested as well.
You can check the following foods as well.
- Dry fruit
- Dry pet food
All dry foods stored in kitchen cabinets need to be discarded if you see any traces of an infestation such as chewed packaging.
Raise indoor temperature
There are other methods of killing these bugs if you still have flour bugs in your house after discarding the infested food.
Most flour bugs like warmth but they hate it too much of it.
Flour bugs begin to die at 73.4℉ degrees. Almost all of them are dead by the time the temperature gets to 131℉ degrees.
This can sometimes be achieved in homes where you can turn up heating considerably or by adding a heater in the proximity of the infested food.
This can also be one of the measures to consider when it comes to killing very difficult-to-spot flour bugs eggs.
Call a professional
Methyl bromide fumigation is one of the methods professionals use to get rid of flour bugs.
These types of bugs are known for infesting homes in high numbers and you might need a professional for the job.
Most flour bugs live up to a year. They reproduce from 7 to 8 months.
During this time, a single flour bug can lay anywhere between 400 and 600 eggs leading to serious food infestation problems in a matter of months.
If you find flour bugs in other areas of the house it might be a good time to call a professional pest controller.
Professionals can also apply insecticides when needed.
While insecticides are normally the last measure against flour bugs in case of minor home infestations, they might be the recommended solution when the infestation spreads.
The insecticide is dangerous to humans as well and professionals need to apply it according to regulations.
How to Prevent Bugs in Flour
Preventing flour bugs is the best method of avoiding them altogether since flour needs to be discarded in case of an infestation.
If you’ve had flour bugs before or if you want to keep these bugs out at all costs you can consider one or multiple strategies as follows.
1. Regular deep cleaning
Poor sanitation is one of the main reasons flour bugs are found in homes.
Rarely cleaning the pantry and having plenty of open dry food is a known breeding ground for these bugs.
You need to regularly clean the pantry to avoid these bugs and other types of bugs such as cockroaches.
Deep cleaning isn’t a guarantee a flour bug infestation won’t happen.
Here’s what to do with a deep cleaning to ensure these bugs don’t infest your flour and other dry foods.
Wash the cabinets with vinegar or soap and water
2. Replace old flour with new flour packages
Replace old dried foods that have been sitting in kitchen cabinets for months
Improve ventilation to avoid mold and high humidity in the pantry
Deep cleaning also involves eliminating all types of other foods these bugs can eat that aren’t of a vegetable nature.
Some flour mites have been known to eat dried meats such as beef jerky. You might need to check other dry foods during the deep cleaning process.
3. Sticky traps
Sticky traps are the most recommended preventive solution against flour bugs.
While these traps don’t eliminate the risk of having flour bug infestation since most of these come from shopping already infested flour, these traps still work to limit the spread of an infestation.
You can limit the spread of crawling flour bugs by setting up sticky traps.
Flying flour bugs will overpass these.
However, pheromone-based sticky traps are the ideal alternative for flying flour bugs.
These traps use a certain lure that ensures you won’t have to deal with the bugs for a long time.
4. Pitfall traps
Pitfall traps are also common against all types of flour bugs.
These types of traps only work with ground-level crawling bugs.
Flour bugs fall and get trapped without a means of escape.
You can spread a few pitfall traps through the pantry or around the kitchen, an area where these bugs can thrive in.
Flour processing facilities have multiple prevention measures in place as well.
Some facilities use certain odors to keep these bugs out. But many also use classic pitfall traps as a backup solution.
Pitfall traps don’t work as well when there’s no lure.
This is why they can come with a pheromone or pheromone-like smell to attract these bugs.
5. Vacuum kitchen cabinets
Frequently vacuuming kitchen cabinets and the entire kitchen is recommended.
You can also vacuum the basement if you store dry foods there.
Long shelf life food such as flour is often forgotten among other long shelf life foods such as pasta.
Even if in the original packaging, the area where these foods are stored should be regularly vacuumed and inspected for bugs.
This is especially true for those living in the South such as residents of Arizona, Texas, California, Florida, and Louisiana.
Southern states have a higher number of flour bugs and a higher risk of a flour bug infestation.
6. Maintain air humidity levels below 65%
Numerous studies show flour bugs love high humidity. They love it so much they can only reproduce in areas of high humidity.
Some species such as Foreign Grain Beetles have even adapted to organic food sources in high humidity environments such as mold.
These bugs can eat mold whenever they cannot find any dry foods.
Most professional pest controllers recommend maintaining safe air humidity levels below the 65% mark.
This might involve using a dehumidifier, especially in areas with high humidity or when storing foods in the basement, as this part of the house has higher humidity.
Monitoring humidity levels is also recommended when preventing another infestation after your pantry has been infested by flour bugs before.
7. Use natural flour bug repellents
Some natural repellents are very good at keeping flour bugs away.
They cannot kill flour bugs directly but they can stop them from spreading and creating a larger infestation problem.
Here are the most recommended natural flour bug repellents.
You can use entire garlic cloves around the pantry to keep flour bugs away. The more garlic you’ll have the fewer the chances of having flour bugs are.
Garlic is known to repel these bugs to the point they try to fly away to escape its pungent smell.
The smell of garlic can be absorbed by the flour, on the other hand.
Cloves are a natural flour bug repellent. The characteristic pungent smell of cloves is something these bugs hate.
Small cloves bags can be stored in cupboards where dry food is stored all the time.
Cloves are also a type of dry food but flour bugs do not eat them due to their highly aromatic profile.
- Bay leaves
Dry bay leaves are successfully used to deter flour bugs. You can sprinkle a few bay leaves around dry food if you plan on keeping it longer than a few months.
Bay leaf cleaning products are also recommended for the pantry and the kitchen as the smell repels other types of bugs as well.
8. Store flour and dry food in plastic containers
Properly storing flour is one of the main methods of avoiding flour bugs.
Storing flour in its original paper bag isn’t recommended if you truly want to keep flour bugs out.
You need to consider plastic or glass airtight containers instead. Here’s how to store flour properly.
- Airtight lid
You need a container that has an airtight lid to store flour to keep flour bugs out.
Airtight lids don’t allow bugs to come into flour or to spread their infestation if you buy already infested flour.
See-through airtight lids are recommended since you might be able to spot any sign of an infestation such as eggs, larvae, or the bugs themselves.
- Clear container
A clear container made from plastic or glass is also recommended. Flour bugs can chew through thin plastic bags but they cannot chew through thick plastic containers.
Glass see-through containers are a good alternative as well. These containers can also be used for other dry foods these bugs eat such as rice and pasta so they don’t have easy access to the food.
- Away from infested foods
Even airtight containers need to be stored in a clean area free from bug infestation.
Accidental infestation is possible even when handling airtight containers.
The worst part is that a bug that makes it inside might not be noticeable for weeks it can take a few days for their laid eggs to hatch and for you to notice the infestation.
9. Store flour in the freezer
30 minutes of high heat exposure is known to kill bugs you find in flour.
You can also kill these bugs by freezing them.
30-45 minutes of exposure to temperatures below the freezing line are known to kill flour bugs.
This is one of the common solutions used to completely kill bugs where you aren’t sure discarding them on your property is a good idea.
Alternatively, you can also consider storing flour in the freezer. Dry flour should still be usable even when stored in a freezer as it should not form clumps.
Those living in remote areas where buying new flour isn’t easy might consider permanently storing it in the freezer to avoid all risks of flour bugs.
10. Store matchboxes next to the flour
Matchboxes are known for having matches with high sulfur content. Sulfur is known to be a flour bug deterrent.
Matchboxes kept around dry food are one of the cheapest methods of keeping dry food bugs away.
Weevils and beetles are mostly deterred by the intoxicating aroma of sulfur.
11. Store flour containers in direct sunlight
Flour weevils love a warm environment but they don’t like too much heat.
Direct sunlight eventually kills flour bugs.
These bugs need a dark place to hide in as many are even nocturnal. They don’t like bright sunlight and the warmth it generates.
Finding a sunny place to store flour might be recommended to either deter flour bugs or kill flour bugs.
Long-term food storage might not benefit from direct sunlight exposure otherwise.
There are many types of bugs in flour. Most eat flour as adults while others only eat flour in their larval stage.
Flour bugs are generally small. They measure around 2.3-3mm, albeit they can be larger than this in some species.
The larvae of these bugs can be as long as 5mm. It can be identified by its movements and white or off-white coloring.
Bugs in flour are a common sight in case of an infestation from another product with flour bugs.
One of the easiest ways to get flour bugs in your home is to purchase flour that’s already infested. This small flour package can quickly lead to a larger bug infestation problem as flour bugs can also eat other types of dry foods.