A flour weevil refers to a type of beetle that is commonly found infesting stored grain products such as flour, cereals, rice, pasta, and baking mixes. “Flour weevil” is the common name associated the red flour beetle (Tribolium castaneum) and the confused flour beetle (Tribolium confusum). Visually, these beetles appear almost identical to one and other.
Does the UK Have Flour Weevils?
Yes, the UK does have “flour weevils” aka red flour beetles and confused flour beetles.
What does a Flour Weevil Look Like?
Both species of flour weevils are a small, reddish-brown beetles that fit the following description:
Size:
They are relatively small, measuring about 3 to 4 mm in length when fully grown.
Colour:
As their name suggests, they have a reddish-brown body colour, which can vary slightly in intensity.
Shape:
Flour weevils have a slender, elongated, and flat body shape.
Antennae:
This is where the two species differ in appearance. The red flour beetle’s antennae are notable for gradually expanding towards the tip, ending in a three-segmented club, which distinguishes it from the confused flour beetle, whose antennae end abruptly in a larger club shape.
Wings:
They possess wings and are capable of flight, which distinguishes them from some other stored product pests that cannot fly.
Regardless of which of the two types of flour beetles you have (red or confused), the way to get rid of them is the same, so you don’t need to identify the exact species.
Below is a photo of a flour beetle to help you confirm if this is what has invaded your food.
What does a Flour Weevil Eat?
Flour and Meal: Flour Weevils primarily feed on flour and meal products derived from wheat, corn, rice, and other grains.
- Cereals and bread: They will eat pretty much any cereals or bread they can access
- Grains: Flour weevils eat grains and commonly target rice.
- Baking Mixes: Prepackaged mixes for cakes, bread, pancakes, and similar products can also be infested.
- Pet Foods: Dry pet foods, including those for dogs, cats, and birds, are susceptible to infestation.
- Other products: Flour beetles have been reported to eat coco, spices, dried fruit and dry pasta, but the typical target for these insects is milled or ground grains.
Note: In particular, the flour beetle is attracted to grains that are a bit damp. So, the perfect food for flour weevils is packs of cereal, oats, dry pet food or flour that have been opened, only partially used, and then stored on a shelf for a few months, without being put into an airtight container.
What Other Types of Beetles of Eat Flour?
If you find insects in your flour, it might not be the flour beetle. The list of insects below are also commonly known to infest flour. It’s worth making sure that any infestation you have is in fact what you think it is before commencing any type of chemical treatments.
- Flour Mite/Grain Mite (Acarus siro)
- Broadhorned Flour Beetle (Gnatocerus cornutus)
- Coffee Bean Weevil (Araecerus fasciculatus)
- Biscuit Beetles (Stegobium paniceum)
- Foreign Grain Beetle (Ahasverus advena)
- Granary Weevil (Sitophilus granarius)
- Cigarette Beetles (Anobiidae)
What are the Signs of Flour Weevil?
Here are the signs to look out for if you need to confirm whether you have a flour weevil problem:
Live Insects:
Seeing live beetles either crawling around in the cupboards, on surfaces, or directly in the food products is a clear sign of an infestation. If you see the insects you can ID them against the picture provided in this article.
Dead Insects:
Finding dead beetles in or around food packaging or in the food itself can also indicate a problem.
Larvae and Pupae:
Beetle larvae are small, whitish, and worm-like, while pupae might be found within the food or in crevices of packaging or shelves. Discovering only the larvae will not make it easy to ID the flour beetle since many other insects have similar larvae. You’ll need to find an adult beetle for the most accurate identification.
Damaged Packaging:
Holes, gnaw marks, or other damages to packaging are be signs that beetles have chewed through to access the food. But a number of flour-loving beetles can chew through packaging. Look for an adult beetle. Regardless of what insect it is, you’ll need to throw out packaging that’s been penetrated by any insect.
Unpleasant Odour:
Flour beetles can produce a characteristic unpleasant smell, described as mouldy or musty.
Discarded Larvae Skin:
As larvae molt, they leave behind skins, which can accumulate and become visible in the infested products.
How do Flour Weevils Get into Your Home?
The most common way these pests enter homes is by hitching a ride in packaged food products that are already infested.
Other less likely ways in which Flour Weevils might get into your home include:
- Through cracks, crevices, or open windows and doors.
- In apartment buildings they may migrate between units through shared walls.
- The use of previously contaminated containers or bags might even contribute to spreading the pest.
How to Get Rid of Flour Weevils?
Identify the Pest
Before declaring war on flour weevils, it’s essential to know your enemy. Flour weevils are not the only pests that invade flour and cereals. Try to ID and adult insect against a photo.
Inspect for Activity
The first step in dealing with an infestation is to inspect your food storage areas for signs of activity. Look for live or dead insects, larvae, and pupae in and around food packages. Pay attention to flour, cereals, and other dried powdered goods for any unusual smells, clumping, or packet damage.
Clean and Clear
Once you’ve confirmed the presence of flour beetles or any other type of insect in your food storage, it’s time for a deep clean. Dispose of all infested food products by sealing them in a bag and removing them from your home
Vacuum shelves, cracks, and crevices and wash all surfaces with soap and water. Use a strong vacuum with a HEPA filter for the best results
Make sure to thoroughly clean in all nooks and crannies. The insects are very small and you need to make sure you’ve removed them all.
Storage
Store all uninfested food in airtight plastic containers to prevent future infestations.
Apply Insecticides (if you are ok with chemicals)
For severe infestations, you may consider using insecticides as a last resort. Choose products specifically designed for use on flour beetles, and always follow the manufacturer’s instructions to ensure safety. Be cautious about applying chemicals near food or food preparation areas, and explore all non-chemical options first.
Chemical vs Non-Chemical Treatments
When it comes to eradicating flour weevils, there are pros and cons to both chemical and non-chemical treatments. Non-chemical methods, such as cleaning, and trapping are safer for your family and pets but may require more diligence and time to be effective. On the other hand, chemical treatments can offer a quicker solution but come with risks, such as potential exposure to harmful substances.
If you’re interested in a extremely effective, non-chemical treatment, you can contact a pest control expert such as Merlin Environmental.
Pest control professionals such as Merlin Environmental use heat treatment to get rid of flour beetles, without any needing chemicals.
We have special industrial heating equipment that we can use to heat an entire kitchen to 55 degrees Celsius, which will eliminate every living insect, in every single crack and crevice, in the entire room, with a 100% success rate. If you’re interested in this, get in touch.
If you operate a business such as a warehouse where grain is stored, professional heat treatment will be the only viable option for immediate results and regulatory food safety compliance, so do get in touch with us.
How to Prevent Flour Weevils Returning
Here’s how you can prevent these unwelcome guests from making a comeback.
Inspect Regularly
The foundation of pest prevention is regular inspection. Periodically check your pantry and kitchen cabinets for signs of infestation, such as live insects, larvae, or damaged packaging. Early detection can prevent a full-blown infestation.
Proper Storage
Invest in airtight containers for storing flour, cereals, and other dry goods. These containers not only keep food fresh but also prevent flour beetles from infesting your food supplies. Glass, metal, or sturdy plastic containers with tight-fitting lids are ideal.
Buy in Small Quantities
Purchasing food in bulk might be economical, but it increases the risk of infestation and makes food storage more challenging. Buy smaller amounts that you can use within a reasonable timeframe to reduce the chances of weevil infestation.
Examine Packaging before you buy
Before adding any item to your shopping cart, examine its packaging for any signs of damage or tampering, which could indicate a pest problem. Opt for sealed packages and avoid those with holes, tears, or other damages.
Throw Things Out
At the first sign of infestation, dispose of contaminated food products immediately. Seal them in a plastic bag and remove them from your home to prevent the spread of pests. It’s a crucial step in controlling the problem and preventing it from escalating.
Good Hygiene and Cleaning
Maintain a clean kitchen and pantry. Wipe down shelves, cabinets, and counters regularly to remove food residues and crumbs that could attract pests. Vacuuming pantry shelves and cracks can help remove hidden eggs and insects.
Heat and Freezing
Extreme temperatures can be your ally in combating flour weevil infestations. Consider freezing susceptible food items for at least four days to kill any eggs or larvae. Alternatively, you can heat items in the oven at 130°F (54°C) for about 30 minutes. However, use these methods with caution to avoid damaging or cooking the food.
Do Flour Weevils Fly or Bite?
Flour beetles do have the capability to fly, but they don’t fly very often. These beetles are more likely to spread through contaminated food products than through flight.
As for biting, flour beetles do not bite humans.
What Happens if You Eat a Flour Weevil?
Eating a flour weevil, whether in its adult or larval stage, live or cooked, is generally not harmful to humans in terms of toxicity. These insects don’t carry diseases known to affect humans, and their bodies don’t produce toxins that could cause food poisoning.
If you ate some food that had flour weevils, you’ll most likely be fine, particularly if you baked the food first as you might do with affected flour.
However, the dead insect bodies, cast maggot skins, fecal pellets, and secreted liquids (quinones), can produce extremely pungent and nauseous odour, which can be very off-putting to anyone consuming the contaminated food. It’s best not to serve food that’s been contaminated, but to bin it instead.
Summary
Flour beetles/weevils can cause extensive damage to food products and can result in high grocery costs, as impacted food will need to be thrown out and likely replaced.
By identifying these pests correctly, taking prompt action to eliminate them, and employing preventative measures, you can protect your home or business from future infestations.
If you need help identifying whether you have flour beetles, or if you want assistance in getting rid of an infestation, Merlin Environmental is a UK pest control company offering nationwide pest control solutions for flour beetles and all other insects. If you have a pest problem reach out to us.
