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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.
I've started just storing my flour in the freezer, regardless. I think it makes more sense than having to worry about those doggone weevils, and since I buy small bags of flour, as a rule, it doesn't generally crowd my freezer too much.
I have also found that since I moved into a house with 50s era metal kitchen cabinets, the weevil problem seems to be minimized. Maybe they aren't as apt to breed in metal cabinets as they are in those made from wood or MDF. I don't know if that's the case, but it has seemed like that to me, and we've been living here since 2008. I don't think I've seen a single weevil. They were real problems in our apartment complex, and my mom, whose kitchen has wooden cabinets, has also had issues with them. She keeps her flour in the freezer, too.
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