Home-stored product entomology

Home stored product entomology is the study of insects which infest foodstuffs stored in the home. It deals with the prevention, detection and eradication of the pests. The five major categories of insects considered in this article are flour beetles, the drugstore beetle, the sawtoothed grain beetle, the Indian meal moth and fruit flies.

This is an important branch of forensic entomology because consumers who find contaminated products may choose to take legal action against the producers. Suitably qualified entomologists are likely to be able to determine the identity of contaminant species, even when no insects are found and the only evidence of infestation is the resulting damage. They should also be able to determine whether the foodstuff was contaminated before or after purchase.

In the United States, companies are required by the U.S. Food and Drug Administration (FDA) to have no more than a certain number of larvae, insects or insect fragments in their products; when this defect action level is exceeded, a consumer can pursue legal remedies.

Two different types of beetles are classified as flour beetles: the red flour beetle and the confused flour beetle. Both are similar in physical characteristics. They are flat and oval in shape and usually range around 1/8 inch long. Their exoskeletons are reddish brown with a shiny and smooth texture. The eggs, larvae, and pupae resemble each other closely in physical features, as well. The eggs usually tend to be a white color, or at times even colorless. They are very small in size and have a sticky outer covering that causes certain food particles to stick to them. The larvae have six legs, with two pointy projections toward the caudal end. Finally, the pupal stage (a cocoon-like form) is usually a white or brownish color. The beetle life cycle lasts about three years or more, with the larval stage ranging anywhere from 20 to over 100 days, and the pupal stage around eight days. Beetles usually breed in damaged grain, grain dust, high-moisture wheat kernels and flour. The female flour beetle can lay between 300 and 400 eggs during her lifetime [a period of 5 to 8 months]. The flour beetles mainly infest grains, including, but not limited to: cereal, corn meal oats, rice, flour, and crackers. This type of beetle is the most abundant insect pest of flour mills across the United States. Their small size allows them to maneuver through cracks and crevices and get into the home and other areas. Once they are present in areas with potential food sources, they can infest material such as flour, resulting in a sharp odor or moldy flavor. The red flour beetle is able to fly short distances and the confused flour beetle is unable to fly. While the confused flour beetle is more commonly found in the northern United States, the red flour beetles are more predominant in the southern United States in areas with warmer climates.

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