Managing Beetles in the Pantry
About 300 species of stored product insects could be encountered with about 20 species of primary economic importance, 50 of secondary importance, and the remainder of occasional importance. A first step to effectively manage stored product beetles is to start with identifying the insect first. The variety, number, and small size of many stored food pests can make identification a challenge and they should be identified by an entomologist. Making note of the infested foods and location of the pest can aid in identification.
Once stored product pests have been detected and identified, a thorough visual inspection is needed to find all of the sources where these pests are living and breeding. Success in solving the infestation depends on addressing these breeding sources either by discarding infested product, by freezing or heating it, or returning it to point of purchase or manufacturer.
Preventing pests from entering a home should be the primary goal to prevent future infestations. Inspection of all your food products (including bird and pet foods) is essential. Even clean, insect-free packages of food from the manufacturer can become infested before reaching the consumer. A primary function of packaging is to keep the product clean and pest-free, and packages vary in their vulnerability to insect infestations. Newly hatched larvae of flour beetles, and saw-toothed grain beetles can invade crevices just 0.1 mm in width (about the thickness of a dollar bill).
Other beetles like rice weevils could chew through paper and thin plastic bags to get access to bird seed or pasta products. Inspect packages for obvious gaps, loose seals, tears, ‘vents’, small holes and/or other damage before purchase. Choose packages or products with thicker, smooth layers of plastic and also allow it to be reclosed tightly if not used up all at once. This will eliminate most bad packages that give easy access to food pests like cigarette beetles, drugstore beetles, and warehouse beetles. These small openings allow these beetles to deposit their eggs inside the package.
Most packages have ‘best before’ dates. Do not buy products that have very old dates as they may have more damage from handling and have been at risk of infestation much longer than newer packages. Glass, thick plastic jars, and cans are insect-proof; however once they are open they may be susceptible to invasion, so place unused contents into secure snap-tight containers or thick freezer bags.
Proper storage of grains, cereals, food ingredients or products is a highly significant component of preventing and limiting infestations, especially in homes. Highly attractive or susceptible foods, such as pet foods and birdseed, should be placed in large containers with tight-fitting lids. These items can be stored in cold garages during the winter or in freezers during the summer to give long term protection. Other products, such as flour, beans, pasta, cereal, etc. can be placed in smaller glass or plastic containers. Any package that cannot be reclosed securely with a tight-fitting lid or have thin wrapping should be placed in another insect resistant container. These include paper bags and boxes, sandwich bags, cellophane wrapped foods like pasta, cookies, and crackers.
Newly purchased food products may not be infested, but it is difficult to be certain if they were in a pantry with an infestation. The option to freeze food products you intend to keep is very cost effective. Some foods like bird food may have live insects or eggs in them but are still edible by birds after freezing. Food should be wrapped in plastic and frozen at the coldest temperature possible for at least 7 days. Do not remove from the plastic wrapper after freezing until it is back to room temperature to prevent condensation forming on the food.
In a strict sense, sanitation is the removal of potential food, water, and shelter that could be used by pests. A few flour beetles or grain beetles can develop rapidly into a significant problem if spilled grains and food products are not cleaned up or damaged food packages are not removed or discarded. A thin, almost invisible film of flour dust is a favorite food for flour beetles. Vacuuming up food spills and residues in the food pantry and other seldom-used storage areas (such as the garage or utility closets) is an essential part of controlling a stored product insect infestation. Removing and cleaning food spills around the stove, refrigerator, trash cans, and even the toaster will reduce beetle food. The use of bleach or other detergents does not directly affect or kill insects, but will provide a sanitized food storage area. After sanitation efforts, trap catches for stored food beetles often increase as they search for food. This does not indicate an increase in population, but rather, increased searching activity.
Trapping Or Monitoring
Pheromone and food-baited traps are an effect method of removing the last wandering beetles from the food storage areas. They are also good monitoring tools to help you discover any new infestations that you were not aware of. Pheromones are natural chemicals secreted by insects to attract more insects of the same species.
As with any trap, pheromone traps must be placed correctly. Key placements include areas where an occurrence of infestation exists. Several traps can be placed in a kitchen or pantry at floor level or on each shelf of each cabinet. Pit fall traps with food and pheromone combinations can attract several species of crawling beetles. Species specific traps are also available, but should be used after accurate identification has been made. These traps are recommended for adult beetles that can fly, such as cigarette beetle, warehouse beetle, and drugstore beetle. Such traps can be placed in rooms adjacent to the kitchen or pantry as they are more mobile than crawling beetles, like flour beetles, and grain beetles.
Most pheromone lures and food attractants in traps require replacement on a regular basis. Check the manufacturer’s instructions on replacement times. It is also important to clean or change these units of captured insects. Beetle traps should be checked at least monthly, but can be more often. Food and pheromone traps are especially useful for early detection of an infestation, and this also enables better targeting of treatments and less pesticide use if this option is desired.
Traps and pheromones are not available for all species of stored product insects so regular inspection with a flashlight of the pantry or food storage areas is still an important task.