How to Solve a Current Infestation of Stored Product Pests


Figure 9. Because of their mobility, infestations of stored product pests can spread into areas well away from their original point of origin (often the kitchen, cupboard, or food storage closet). When seeking out the source of a stored product pest, if the infestation cannot be found in the kitchen, look elsewhere. In this photograph, stored product pests were found infesting corn (bird and squirrel food) that had been stored in a utility closet and forgotten.

When looking for the source of a stored product pest infestation, inspect all items containing materials of animal or plant origin, including decorative items such as this ornament made from beans.

Closeup of holes in beans from which cowpea weevils emerged.

To stop a current infestation of a stored product pest, the source of the insects must be found and eliminated. Otherwise, the problem is likely to persist. The infestation can be stopped by finding and removing the insect’s food sources, vacuuming (or removing) food crumbs from hard-to-reach locations in the cupboard, and, when appropriate, eliminating infestations from items deemed nondisposable, such as those with sentimental value. To find insect-infested material, inspect all items listed previously as susceptible to infestation, beginning with those potential sources closest to where most of the adult insects are found. When inspecting open food containers in the cupboard, it is advisable to lightly shake each item. Although stored product pests may not be immediately visible upon inspection, the physical act of shaking often brings small beetles to the surface of the infested food item, where they can then be easily detected. If the sources of insects cannot be found where food is stored (i.e., kitchen, cupboard, or food storage closet), then look elsewhere. Items not considered human food may support a population of a stored product pest. Bird seed and dry pet food are common sources of stored product pest infestations (Figure 9). Other sources may include wall and table decorations, ornaments, potpourri, and jewelry that contains items of plant or animal origin (Figure 10). When an infested item is found and the decision to discard it is made, the item should be tightly sealed within a bag and immediately placed in an outdoor trash receptacle for removal. The mobility of stored product pests is an important factor to consider when searching for the sources of an infestation. The adults of some species are excellent fliers, very active, and perhaps attracted to lights. Because of their mobility, infestations (or simply individual adults) can spread into areas well away from their original point of origin or primary breeding site (Figure 9). The adult stage of stored product pests should be viewed as the stage that initiates and spreads the infestation. Adults are also the most commonly seen stage. In contrast, larvae are mostly confined to the food items they infest and are rarely seen. In homes, insecticides can be used to reduce visible populations of adult insects. However, if the only effort at solving the infestation is treatment of adults with insecticides, the problem is not likely to be solved. The infestation will likely persist unless infested material is found and removed, and packages of opened food items are protected from infestation. If an insecticide is used, it is important to first read the product’s label to determine how it can and cannot be used. Insecticides should never be applied directly to consumable food items. Infestations of items that cannot be discarded (e.g., items with sentimental value, jewelry, and home or seasonal décor containing items of plant or animal origin) can be eliminated by exposure to extreme cold. Infested items can be placed in a household freezer and held for six days at 0 degrees F to -2 degrees F (warehouse beetle infestations may require longer exposures), keeping in mind that the efficacy of extreme cold as a control method is dependent upon a number of variables, including temperature achieved at the infestation site, time held at target temperature, insect species, and degree of insect protection inside infested items (insulates insects from extreme temperatures).



“Stored Product Pests in the Home” is a production of the Department of Entomology and Plant Pathology, University of Georgia. The original authors of this content are Daniel R. Suiter, Michael D. Toews and Lisa M. Ames.