Flour beetles are pests of flour and cereal products. They are among the most important pests of flour and stored products. They are common in homes and grocery stores. They also infest mills and food processing facilities.
Two of the most common flour beetles are the confused flour beetle, Tribolium confusum (duVal), and the red flour beetle, Tribolium castaneum (Herbst). These are small beetles. The adults are about 3 to 4 mm long. They are reddish brown in color. There are differences between the antennae of these two beetles. Since these insects are so small, it usually requires a magnifying glass to recognize these differences.
The flour beetles include several species. Some of the other flour beetles are the black flour beetle, the false black flour beetle, the broad horned flour beetle, the slender horned flour beetle, the depressed flour beetle, the small eyed flour beetle and the long headed flour beetle. These do not occur as often as the red and the confused flour beetles. Flour beetles do not attack whole grains. The female beetle deposits eggs directly on flour, cereal, dry pet food or other similar products. The females deposit a few eggs each day in the food that she is eating. The egg laying can last several months. The eggs are hard to see in flour or meal.
The larvae hatch and begin to eat the material where they hatched. The larvae are 4 to 5 mm long. Flour beetles can develop from egg to adult in as little as seven weeks. In warm environments, there can be four or five generations per year.