(Left) The red flour beetle is of Indo-Australian origin and is found in temperate areas, but will survive the winter in protected places, especially where there is central heat. In the United States, it is found primarily in the southern states.
(Right) The confused flour beetle, originally of African origin, has a different distribution in that it occurs worldwide in cooler climates. In the United States it is more abundant in the northern states.
Comparison of adults of the red flour beetle (left), Tribolium castaneum and the confused flour beetle (right), Tribolium confusum. The antenna of the red flour beetle ends in a 3-segmented club and the sides of the thorax are slightly curved. The confused flour beetle has no apparent club on the antennae and the sides of the thorax are straighter. Graphics by USDA.
The red and confused flour beetles may be present in large numbers in infested grain, but are unable to attack sound or undamaged grain (Walter). The adults are attracted to light, but will go towards cover when disturbed. Typically, these beetles can be found not only inside infested grain products, but in cracks and crevices where grain may have spilled. They are attracted to grain with high moisture content and can cause a grey tint to the grain they are infesting. The beetles give off a displeasing odor, and their presence encourages mold growth in grain.
Keep in mind that these beetles may infest areas other than the pantry. Be sure to inspect spices, pet food, and flower arrangements. Also keep in mind that some stuffing in furniture or stuffed animals may have natural products that these beetles could feed on. Also be aware of areas in which any of these products may have spilled, like under the refrigerator or stove. These beetles are able to locate very small bits of food. Once all of the infested material has been removed, be sure to vacuum and clean up the area around the infestation. If you have shelf paper, it would be wise to remove it, thoroughly clean under it with soap and hot water, and replace it with new paper. Be sure to pay close attention to the cracks and crevices of any cabinets. To prevent re-infestation, all grain products should be stored in containers with tight fitting lids, or stored in the freezer. Also consider where the infestation came from. It is likely that you could have a re-infestation by purchasing infested grain products from the same business. When shopping, look for "leaky packages" before buying a product.
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