Flour Beetles or Weevils - Facts, Prevention and Flash Fiction

The rice weevil (Sitophilus oryzae) attacks grains. Weevils are small beetles with an elongated head that forms a snout. Flour beetles are somewhat similar to grain weevils and are often mistakenly called flour weevils.
The rice weevil (Sitophilus oryzae) attacks grains. Weevils are small beetles with an elongated head that forms a snout. Flour beetles are somewhat similar to grain weevils and are often mistakenly called flour weevils. | Source

What are Flour Beetles or Flour Weevils?

Flour beetles are annoying insects that infest flour and make it unusable. They are also known as flour weevils. An examination of infested flour often reveals little brown or dark red insects crawling through the flour. The sight is not a pretty one. Flour beetles aren't poisonous, but they do produce an unpleasant odour and can cause flour to become grey. Although much of our food is contaminated by insects and their secretions, the thought of eating flour beetles or their eggs is unappealing for most people.

The most common beetles that infest flour are the confused flour beetle and the red flour beetle. Sometimes the pest in flour is a moth instead of a beetle, however. The Indian meal moth is often detected by the silk strands that it creates in flour. These produce a structure that resembles a cobweb and traps grains of flour.

In this article I'll focus on the confused flour beetle, which is common in the cooler, more northern part of North America where I live. The red flour beetle generally lives further south but has a very similar appearance and biology to the confused flour beetle.

Grain Weevils

There are several weevil species that infest grains and are sometimes kitchen pests. The female inserts an egg into an intact grain kernel and then seals the hole. The new beetle develops within the grain. Since flour beetles are a kitchen pest, infest a grain product and look somewhat like grain weevils, they are often mistakenly called "flour weevils."

Maize is another name for corn. This is a maize weevil. The elongated snout or rostrum is typical of weevils.
Maize is another name for corn. This is a maize weevil. The elongated snout or rostrum is typical of weevils. | Source

The Confused Flour Beetle

Although I'm not fond of the insect, I love the common name of the confused flour beetle. It makes me think of a little insect scurrying through a bag of flour in a panic as it tries to find its way out. In reality, the name (apparently) refers to the fact that the beetle is easily confused with the red flour beetle.

The scientific name of the confused flour beetle is Tribolium confusum, while that of the red flour beetle is Tribolium castaneum. The two insects sometimes live in the same area. For many people, distinguishing between the species isn't important. They both produce the same unpleasant effects and they can both be removed by the same methods. For beetle fans and entomologists, however, identifying the species is useful.

Beetles

All beetles belong to the class Insecta and the order Coleoptera. True weevils, such as grain weevils, belong to the family Curculionidae in the order Coleoptera. Confused and red flour beetles belong to the family Tenebrionidae.

The confused flour beetle is one of the insects that is often referred to as a flour weevil.
The confused flour beetle is one of the insects that is often referred to as a flour weevil. | Source

How to Recognize a Confused Flour Beetle

The confused flour beetle is a shiny, red-brown insect with a flattened body. It's one eighth to one quarter of an inch in length. While its species may not be recognized without magnification, the beetle is not microscopic and can definitely be seen. Its presence in foods such as flour is one clue to its identity. The beetle has the following features.

  • Like other insects, the body of the confused flour beetle is divided into three sections - head, thorax and abdomen.
  • There are a pair of segmented antennae attached to the head.
  • The ends of the antennae have a clubbed appearance. There are four segments to each club. The segments gradually increase in size from the beginning to the tip of the club. The club of the red flour beetle contains only three segments and is more distinct.
  • When the beetle is viewed from the side, an observer can see that the large compound eyes are notched.
  • Three pairs of legs are attached to the thorax. The legs are jointed, as in other insects.
  • There are two pairs of wings. The outer pair are known as the elytra. The elytra are tough and protect the membranous inner wings, which in most beetles are used for flying. The confused flour beetle doesn't fly, however, while the red flour beetle does.

The red flour beetle generally has a more distinctive club on its antennae than the confused flour beetle. In addition, the club contains only three segments.
The red flour beetle generally has a more distinctive club on its antennae than the confused flour beetle. In addition, the club contains only three segments. | Source

Flour Beetle Colour

The colour of confused and red flour beetles depends on factors such as lighting and whether an insect is living or dead. It isn't a reliable feature for distinguishing the two species.

Confused Flour Beetle Biology

Life Cycle

During mating, the male confused flour beetle inserts a package of sperm known as a spermatophore into the female's body. The female stores the sperm until she is ready for the sperm to fertilize her eggs. Once they are fertilized, the eggs are laid. The female lays several hundred eggs, but not at the same time. The process takes months. The eggs are covered with a sticky material which enables them to stick to flour grains.

The eggs of the confused flour beetle are white in colour. Unlike the adult beetles, they are microscopic. An egg hatches into an elongated and segmented larva which is yellow or light brown in colour. The larva eventually turns into a pupa. The pupa undergoes metamorphosis and changes into an adult beetle.

Feeding

Confused flour beetles chew, but they don't bite or sting humans. They can't break through intact grain but may be found around damaged grain where there is grain dust. They can easily break through paper and cardboard food packaging, however. In addition to feeding on flour, they eat foods such as cake and pancake mixes, cereals, crackers, spices, chocolate and even dry dog and cat food. The good news is that the beetles don't damage furniture or buildings and aren't dangerous to humans even if they are eaten.

A Red Flour Beetle Feeding

A Flour Beetle Infestation

If you experience a flour beetle infestation, the source of the problem may not be your home. Confused flour beetles enter flour in warehouses and grocery stores as well as homes. They are common pests. Purchased flour may already contain beetle eggs.

Once beetles are visible in flour, the flour generally needs to be thrown away. The beetles could be killed and/or removed instead if a person prefers to do this. If there are lots of dead beetles in the flour they will be hard to remove, however. In addition, they may have changed the taste and colour of the flour and may have encouraged the growth of mold. Another thing to keep in mind is that the infested flour will contain beetle feces and larval cases as well as eggs and intact beetles. Personally, I would rather discard an obviously infested bag of flour than try to clean the flour.

Flour Beetles

How to Control and Prevent a Flour Beetle Infestation

I have experienced a flour beetle infestation. Discarding the flour, cleaning the cupboard shelves thoroughly and putting new flour in a screw-top canister solved the problem for me. There are other steps than can help, however. The following ones are often recommended by pest control agencies and entomologists.

  • When new flour is purchased, transfer it from the bag to a glass or heavy duty plastic canister that has a secure lid. Don't leave the flour in its bag for a long time before you transfer it.
  • Buy flour in small quantities so that it can be used up quickly before an infestation begins.
  • Keep shelves of food storage cupboards clean.
  • If you're recovering from a flour beetle invasion, clear shelves with a vacuum cleaner to remove insects and then wash the shelves thoroughly. Pay special attention to cracks and corners as you clean. Dry the shelves well after washing them.
  • Remove shelf paper before cleaning, if you use it, and cover the shelves with new paper once they are dry.
  • Dispose of infested products outside the home to prevent reinfestation.
  • Inspect other food packages for beetles before putting them back in the cupboard in case the beetles have spread.
  • Consider subjecting flour to a freezing temperature after purchase. This will kill eggs and beetles. (It won't make them disappear, though.) Maintaining a deep-freeze temperature of 0ºF for four days is recommended.
  • Heating the flour can also kill insects. A temperature of 130ºF and a time period of thirty minutes are recommended. (I have neither frozen nor heated my flour before use, so I don't know how the temperature change affects its taste. In addition, heating whole grain flours before use may damage them and shorten their lifespan.)
  • If you find beetles in flour and remember where you bought the product, it might be a good idea to buy your flour somewhere else for a while.

Bread from a bakery
Bread from a bakery | Source

Flash Fiction

I'm fascinated by nature and biology. As I explore the natural world I often find inspiration for creative writing, including flash fiction. The definition of flash fiction varies. Some people say that a flash fiction story should be no longer than 1000 words, some use a 500 word limit and others set a limit of only 300 words, for example.

Flash Fiction - Bread Flour and Weevils

Rebecca collided with the bakery door as the wind and rain pushed her into the building. "Five pounds of bread flour with weevils, please," she gasped to the shopkeeper, trying to catch her breath.

"None of our flour has weevils. We run a clean establishment and follow all the health rules," the shopkeeper snarled, simultaneously smiling at the other customers.

"I promised my children that they could play with some weevils today," Rebecca complained. "A bakery that mills so much flour ought to have weevils!"

"All of our products are in pristine condition," the shopkeeper said, giving Rebecca the evil eye. "We would never allow insects on these premises!"

"I have lots of weevils in my house," said a friendly voice. Rebecca turned to see an elderly woman drinking tea at a table. "Of course, they only enter my flour with permission," the woman laughed. "One lump or two?" she asked with a smile.

Now this sounds promising, thought Rebecca. "No sugar for me," she said, sitting down at the table. "I don't suppose you have lemon?"

"Well, you are a woman after my own heart!" the old lady exclaimed. "I always carry a lemon with me for emergencies like these, as well as my little pot of honey. It's a great combination for a cold."

"I don't have a cold," Rebecca said, just before she sneezed loudly. The two women burst into laughter. The shopkeeper brought Rebecca some tissues, slamming the box on the table.

"I really don't know why weevils are so unpopular," the elderly woman lamented, stirring lemon juice and honey into Rebecca's tea. "They have much to offer us. It's wonderful to find someone else who likes them!"

"It's the youngest, really. She's never seen a weevil before," Rebecca explained as she drank some tea. She was surprised and embarrassed to feel tears welling up in her eyes.

"Poor thing! Weevils are so enticing. Your daughter deserves to meet one," said the woman. "I'd love to give her some of mine."

"That's very kind of you. Do you live nearby?" Rebecca asked, patting her eyes with a tissue.

"If you don't mind, I'd prefer to go to your home. I don't have the opportunity to visit people very often these days. Would four o'clock be a good time to arrive?" she inquired.

How sad, thought Rebecca. "Of course. I live about a twen - forty minute walk away, though," she said, considering the women's age and frail appearance, "and the weather is terrible. There's no bus, either."

"Oh, the trip's no problem. I have my own transport and I enjoy travelling through a storm," the woman said, smiling as she sipped her tea. "Meeting your children would be delightful. We evils love a chance to visit!"

Time for tea
Time for tea | Source

© 2015 Linda Crampton

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Comments 56 comments

Jackie Lynnley profile image

Jackie Lynnley 15 months ago from The Beautiful South

What a delightful read! All those great facts and then a story! This has been such a fun Saturday evening reading here at HP! Great job.

I don't recall ever seeing a flour beetle, seems odd, but I always have kept flour and sugars tightly sealed. Ugh, look like roaches and I sure hate those buggers!


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Hi, Jackie. Thanks for the comment. I hope you never discover flour beetles in your home!


drbj profile image

drbj 15 months ago from south Florida

This could easily be titled, Alicia, Everything you Never Wanted to Know about Beetles and Weevils. Very comprehensive as all your hubs are. I could picture that confused beetle wandering around in the flour crying, 'Who am I? Where am I?"

Loved your fiction, too, with that great kicker at the end. My kind of reading, m'dear.


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Thank you very much for the visit, drbj. I appreciate your comment a great deal! I'm glad that you enjoyed the hub.


EsJam profile image

EsJam 15 months ago from Southern California

Alicia, 'm lady!

What a nice hub, and informative. You've got me thinking about my bag of flour sitting on the shelf! I keep some in a air tight container that I use and when that is done, I transfer over from the bag. I sure hope I haven't served my family any tiny critters!

You offer some great advice. Thanks!

essie

p.s. Delightful flash fiction. Delightful!


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Your flour container sounds great, essie. Thank you so much for the comment about the hub and the story! I appreciate your visit, as I always do.


Vellur profile image

Vellur 15 months ago from Dubai

Great hub with a lot of information about the confused flour beetle. Buying small quantities of flour and storing them in air tight jars is the best thing to do, as you have mentioned. Enjoyed reading the flash fiction.


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Hi, Vellur. Thank you very much for the visit. I appreciate your comment.


whonunuwho profile image

whonunuwho 15 months ago from United States

Nicely done Alicia and very interesting info. Much here that we all need to know about. Thank you for sharing this. whonu


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Thank you very much for the comment, whonu.


billybuc profile image

billybuc 15 months ago from Olympia, WA

I don't think I've ever seen a flour beetle. Ugly little suckers, aren't they? Thanks for the info. It was cool to see a flash fiction at the end. Well done, Linda.


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Hi, Bill. Thanks for the comment. Yes, flour beetles do have an ugly aspect, and they can definitely be annoying. I think they're interesting, though!


Faith Reaper profile image

Faith Reaper 15 months ago from southern USA

Oh, I can't stand looking at them and so I scrolled down to the solutions section, which is great! I love your flash fiction and that ending there ...

You always write such comprehensive hubs to educate, Linda. Sharing everywhere


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Hi, Faith. Thanks for reading the hub even though you hate the appearance of the insects! Thank you very much for the shares, too. I appreciate your support a great deal.


Larry Rankin profile image

Larry Rankin 15 months ago from Oklahoma

Love how you parlayed your informative article into a bit of amusing flash fiction.

I've been lucky enough not to have to deal with these critters before, knock on wood.


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Hi, Larry. Thanks for the comment. I always appreciate your visits!


Rachel L Alba profile image

Rachel L Alba 15 months ago from Every Day Cooking and Baking

I'm very happy I read that you should transfer your flour to a plastic air tight container or another container the same. The thought of those beetles in my flour is creepy. Thanks for the hub and warning. lol

Blessings to you.


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Hi, Rachel. The idea of beetles in flour is a bit creepy! Thanks for the visit. Blessings to you, as well.


adevwriting profile image

adevwriting 15 months ago from United Countries of the World

The hub was very interesting and instructive to read, including the flash fiction. Thanks for sharing such amazing info!


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Thank you very much for the lovely comment, adevwriting!


North Wind profile image

North Wind 15 months ago from The World (for now)

I have had my run-in wih weevils before in flour.To make things easier I put my flour in the fridge. It doesn't change the taste or texture and I never have weevils. I tried the glass container but they still managed to appear so that is how the fridge got involved!


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Thank you very much for sharing your experience, North Wind! I appreciate your comment.


annart profile image

annart 15 months ago from SW England

Hi Linda. Love the ending of your flash fiction; wonderful playing with the word like that!

I've had flour with weevils in it and I chucked it away. Hasn't happened since. Lots of information here which is fascinating. I also thought the 'confused' weevil was a great name - thoughts of it wondering what on earth it was doing, or whether it belonged to one family or another!

Refreshingly different subject and great hub, Linda.

Ann


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Thank you very much, Ann. I appreciate your visit and your kind comment a great deal!


Mel Carriere profile image

Mel Carriere 15 months ago from San Diego California

I loved your unusual story with the creepy twist at the end. As usual, I also learned some interesting natural history facts. Wonderful hub and story! You have a gift for dialogue.


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Thank you for the lovely comment, Mel! I appreciate your visit and the comment very much.


Pollyanna Jones profile image

Pollyanna Jones 15 months ago from United Kingdom

We first discovered flour beetles a few years ago when I was about to do some baking. I saw little holes in the flour, and upon tipping it out into the bowl, found half a dozen of these little scamps. We emptied the entire cupboard to clean it out, and threw the flour away. I was told that their eggs must have been in the packaging and that is how they came inside the house? It was quite a surprise to find them!


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

I'm sure it was a surprise, and an unpleasant one, too! Unfortunately, flour does sometimes contain flour beetle eggs. I think that's how the beetles entered my kitchen.


aviannovice profile image

aviannovice 15 months ago from Stillwater, OK

The information was terrific, and I sure enjoyed your wicked little twist at the end of the fiction. Great work.


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Thanks, Deb. I appreciate your comment!


Nell Rose profile image

Nell Rose 15 months ago from England

lol! I did smile at the confused flour beetle, after reading why it was called that it did make sense, but still made me laugh! and a great story to go with it too, nell


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Thank for the visit, Nell. I appreciate your comment.


bdegiulio profile image

bdegiulio 15 months ago from Massachusetts

Hi Linda. I have never heard of the Confused Flour Beetle. While I like the name I would not want to come across these little pests in my home. Loved the Flash Fiction. Thanks for the education. Great job.


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Thank you very much for the kind comment, Bill. I hope I never encounter flour beetles in my home again. An infestation is interesting to write about but not so much fun to experience!


thumbi7 profile image

thumbi7 15 months ago from India

Very interesting hub

These beetles grow in rice also; not only in flour.

But it is easy to wash and clean rice rice and get rid of them before cooking


AliciaC profile image

AliciaC 15 months ago from British Columbia, Canada Author

Hi, thumbi7. Thanks for sharing the tip about getting rid of rice weevils. They aren't quite the same as flour weevils, but they sound like they are just as annoying!


FlourishAnyway profile image

FlourishAnyway 14 months ago from USA

The tips on how to get rid of them were especially helpful. I'd take the stuff back to the store and demand a refund, receipt or not. I like your flash fiction at the end as well.


AliciaC profile image

AliciaC 14 months ago from British Columbia, Canada Author

Thank you, Flourish. Getting a refund for infested flour is a good idea!


AudreyHowitt profile image

AudreyHowitt 14 months ago from California

Loved this story! Hate the flour beetles though--I had a bout with them last year--yuck


AliciaC profile image

AliciaC 14 months ago from British Columbia, Canada Author

Hi, Audrey. Thank you very much for the comment about the story. I sympathize with your experience with flour beetles!


DDE profile image

DDE 14 months ago from Dubrovnik, Croatia

A very interesting story and you made it very creative.


AliciaC profile image

AliciaC 14 months ago from British Columbia, Canada Author

Thank you, Devika. I appreciate your visit.


MartieCoetser profile image

MartieCoetser 14 months ago from South Africa

I always double check cake and maize flour before using it. Anything weird in it, and the entire batch will end up in the rubbish bin.

Thank you for a very interesting and informative hub about flour beetles, Alicia. You flash fiction is excellent with a surprising end.


AliciaC profile image

AliciaC 14 months ago from British Columbia, Canada Author

Thank you very much for the kind comment, Martie. Having experienced one flour beetle infestation, I always check my flour carefully, too!


truthfornow profile image

truthfornow 14 months ago from New Orleans, LA

Gross huh? I try to keep everything in the fridge just in case bugs try to get in anything. But, I don't have any flour just because I am afraid that I won't use it and it will get infested with bugs lol. Probably need to invest in some sturdy containers.


AliciaC profile image

AliciaC 14 months ago from British Columbia, Canada Author

Yes, an infestation is gross. I think the beetles are interesting, but I don't want them in my flour! Thanks for the visit, truthfornow.


sgbrown profile image

sgbrown 13 months ago from Southern Oklahoma

Great information on these little buggers that seem to find their way into our homes. I have had both the beetles and the moths before. I loved your flash fiction story!


AliciaC profile image

AliciaC 13 months ago from British Columbia, Canada Author

I sympathize with your experiences with flour pests, Sheila! Thank you very much for the comment about the story.


Perspycacious profile image

Perspycacious 11 months ago from Today's America and The World Beyond

Cute flash fiction story I presume is of your creation. No critters in our flour, but a reminder to watch out for any in the future.

A note: years ago, about 1948 my parents were moving from Arlington, Virginia to Maine. Cockroaches were constant concerns in Arlington and my mother made every possible effort to not have any make the move with us, but low and behold some had squeezed into the moving van and made the trip north to seem a problem until some earwigs came inside with some ears of corn from our garden. The earwigs eliminated the cockroaches and became honored visitors in the pecking order of intrusive insects.


AliciaC profile image

AliciaC 11 months ago from British Columbia, Canada Author

Hi, Perspycacious. Thanks for the comment, Yes, I did write the story. Thanks for sharing your own interesting story!


Peggy W profile image

Peggy W 9 months ago from Houston, Texas

Cute story at the end.

When I was a child growing up in Wisconsin with my mother making all of our bread, she used to buy her flour in huge sacks. We never noticed weevils. When moving to Texas the first 25 # sack contained weevils. When my mother told our neighbor she said...oh no problem. Just some extra protein! She was probably? kidding. From that point on my mother purchased flour in 5 # sacks.

If we purchase flour and it does not all fit in our plastic cannister, we do freeze it. I have never noticed any difference in the flavor or performance of the flour.

Interesting information about weevils and flour beetles. Happy to share and pin to my insects board.


AliciaC profile image

AliciaC 9 months ago from British Columbia, Canada Author

Thank you very much for sharing the information, Peggy. I've never bought flour in sacks, so it was interesting to read your story. I appreciate the pin, too!


moonlake profile image

moonlake 9 months ago from America

I put just about everything I bring in the house into a glass jar, tea bags, sugar flour and corn meal.

I always worry about bugs. When we had a bird I once brought bird seed home from the store opened the box and it was crawling with bugs. I wonder how many of the bugs got out of the box and went into other items in the store before I bought it home. Enjoyed your hub.


AliciaC profile image

AliciaC 9 months ago from British Columbia, Canada Author

Your storage plan for food is a great idea, moonlake. Discovering so many bugs in the bird seed package must have been a shock. I would have been very worried that the package contained harmful material for the bird. Thanks for commenting.


teaches12345 profile image

teaches12345 2 months ago

Fact and fiction was a great mix here on beetles. A long time ago I purchased a bag of flour that proved insect infestation after a few days. It was not a pleasant sight. I did as you suggested with the cleaning. I am thinking of putting my flour in the freezer first from now on.


AliciaC profile image

AliciaC 2 months ago from British Columbia, Canada Author

Hi, Dianna. Thanks for the visit and the comment. Insects in flour are always an unpleasant sight. I hope I never encounter them again!

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    Linda Crampton (AliciaC)1,249 Followers
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    Linda Crampton is a teacher with an honours degree in biology. She loves to study nature and write about animals and plants.



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