What are Flour Bugs?

Flour bugs are usually a type of weevil. Weevils are members of the beetle family, which is composed of over 60,000 species. The weevils found in flour are often one of five similar species, beetles smaller than a quarter of an inch (5 millimeters) in length when fully grown. These beetles are found in flour as they are highly adapted to the dry environments of grains and other packaged dry foods, such as nuts, seeds, breakfast cereal, and pancake mix.

Due to their small size, it is easy for flour bugs to penetrate packaging seals such as the paper bags that flour is marketed in. When found infesting a cupboard or bag of flour, cleaning the area and throwing out the flour may not solve the infestation problem. It is entirely possible that the weevils were already in the flour before it was purchased, and bringing it home may have spread flour bugs to other food storage areas. They are often hard to remove completely because they are highly resistant to both insecticides and radiation, and their minute size makes them easy to overlook.

Some of the names that these insects are known by include snout beetles, mealworm beetles, and red flour beetles. One of the most common varieties is the red flour beetle, which has a reddish brown color to it. It is of Indo-Australian origin, but is now found worldwide. Despite minor variations in the species, they exhibit similar behavior patterns and are a common infestation problem throughout all the major agricultural grain industries. Boll weevils are a close cousin to flour bugs and a major pest in cotton production as well.

Removing flour bugs from a pantry once discovered is possible if one applies thorough cleaning methods to the task. It is recommended that every food package that has evidence of flour bugs be completely thrown out first, not placed in trash cans in the house. Then a thorough cleaning of the cupboard area with a one-quarter solution of bleach to three-quarters of water should be done. Allowing the area to dry overnight and storing any suspected pantry food in the freezer for about a week should kill off any surviving grain weevils.

To avoid future infestations, all dry grain products should be transferred to air tight plastic or glass containers once brought home. Freezing any new foods of these types brought into the home, for several days, will also kill any potential flour bug eggs or larvae that are otherwise overlooked. Bay leaves are also known to deter the presence of flour weevils. Including a fresh, dried or ground bay leaf in food packaging or cupboards will help keep them out in the future.

Flour bugs are typically small insects that infest stored grains and dry goods, most commonly being either weevils or beetles. Weevils, like the rice weevil and the granary weevil, are true bugs that belong to the family Curculionidae. They can actually lay eggs inside grain kernels, leading to an infestation from within. Flour beetles, such as the red and confused flour beetle, are part of the Tenebrionidae family and feed on the outside of grains.

Flour bugs often enter homes through purchased food items that are already infested. They can also make their way in through small openings or cracks, seeking out food sources like flour, rice, and other grains. Once inside, they can quickly spread to other pantry items if not contained. According to the University of Kentucky College of Agriculture, Food and Environment, a single female weevil can lay up to 400 eggs, which can lead to a significant infestation in a short period of time.

While the thought may be unsettling, accidentally ingesting flour bugs or their larvae is generally not harmful to humans. They do not carry diseases and are not toxic. However, their presence can degrade the nutritional quality of food and may cause psychological discomfort. It's important to note that severe infestations can lead to food waste and economic loss.

Signs of a flour bug infestation include seeing live or dead insects in your grains, flour, or pantry, as well as larvae or pupae. You might also notice a musty or unpleasant odor, or the flour may appear clumped due to the bugs' secretions. If you spot fine webbing in your flour, it's a clear indicator of an infestation.

To prevent flour bugs, store grains and dry goods in airtight containers made of glass, metal, or sturdy plastic. Regularly clean your pantry shelves to remove any spilled food that could attract pests. Consider freezing grains for at least 48 hours before storing them to kill any eggs or larvae. The University of California Statewide Integrated Pest Management Program suggests maintaining a cool, dry environment in your pantry to deter these pests.

The best way to get rid of flour bugs is to first remove all infested items from your pantry and dispose of them securely. Vacuum the shelves and crevices to remove any remaining insects and their eggs. Wash the area with soapy water and consider using natural deterrents like bay leaves or diatomaceous earth. For persistent problems, consult a professional exterminator who can provide targeted treatments.