Pantry pests are most commonly found in stored food products (people and pet foods) such as: flour, cereal, dry pasta, dry pet food, powdered milk, corn starch, crackers, spices, breads, bird seed, dried nuts and fruit. They become especially troublesome when these foodstuffs are stored in paper containers and go unused for extended periods of time.
These pests are important to the homeowner because they cause food waste and infestations can be persistent. Pantry pests are usually brought into homes in packaged foods, although they may enter from outside sources, or from adjacent apartments. Their presence in the home does not necessarily reflect on the quality of the housekeeper.
The majority of these pests are either beetles or moths. The adult stage is the most easily detected as they often leave the infested material in search of new locations, or are attracted to lights. The larval or immature stages are either caterpillars or grubs. These spend most of their life in the infested material, and are usually similar in color to the food that they are living in. The eggs of these insects are quite small and usually go unnoticed. The pupal stage may take place away from the infested food in corners or cracks in the cupboards or packaging. The length of time to complete their life cycle varies greatly, depending on temperature, relative humidity, and the quality of the food supply. Most stored food pests can complete several generations in one year. They can also breed continuously as they usually exist in favorable conditions Both can be eliminated by a proper search for the infestation and treatment with traps and/or crack and crevice aerosols.
Infestations are easy to overlook because the insects involved are quite small, especially the egg and larval stages. Often the first indication of the infestation is the appearance of small moths flying about or the presence of beetles in or near the food package.
♦ Place exposed food in containers with tight-fitting lids.
♦ Periodic cleaning of the shelves helps to prevent infestation of stored food products by pantry pests. Certain pantry pests need only small amounts of food to live and breed.
♦ Some infestations of packaged food originate in the food-processing plant or warehouse. Broken packages should not be purchased, or should be exchanged for unbroken packages when discovered, for the chance of these being infested is greater than for perfectly sealed ones.
♦ Do not mix old and new lots of foodstuffs. If the old material is infested, the pest will quickly invade the new.
♦ If you are unsure about an item being infested, place it in a plastic bag where you will be able to catch anything that emerges. If you find the pantry pest accumulating in the bag, you know the foodstuff is contaminated and needs to be discarded. To insure any item is pest free, store it in these clear bags for at least a month. Sometimes it takes even longer for the adults to emerge.
♦ Infestations are most likely to occur in packages that have been opened for the removal of a portion of the contents and then left unsealed for long periods. Some of the pests may find their way into other food packages, but even those in a single package may become so numerous that large numbers may find their way into every suitable material in the home, and will eventually crawl over floors, climb up walls, and gather about windows.
♦ Clean old containers before filling them with fresh food. They may be contaminated and cause a new infestation.
♦ Make sure that cabinets and storage units are tight and can be cleaned easily.
♦ Store bulk materials, such as pet foods, in containers with tight-fitting lids.
♦ Keep storage units dry. This is important because moisture favors the development of pantry pests; dryness discourages them.
♦ Some pantry insects breed in the nests of rodents and insects and may migrate from these into homes. Eliminate any nests found in or near the home.
♦ Pantry pests can also breed in rodent baits. Be sure to frequently check and discard infested baits.
When packages of food are found to be infested with moths or beetles, either low or high temperatures may be used to control the infestation.
Insects are cold-blooded; their body temperatures closely follow that of their environment. The most favorable temperature for most pantry pest is about 80°F. Above 95°F or below 60°F, reproduction and survival is greatly reduced. When temperatures are lowered, insect activity decreases until all activity stops. The quicker the drop in temperature, the quicker the kill.
Although insects will be killed, their bodies will remain in the food unless sieved out. An exposure of 2 to 3 days to temperatures of 5°F or lower kills the more susceptible stages (larvae and adults), but eggs require longer to kill (3 weeks). An alternative is to freeze the food for a week, remove it from the freezer for a few days, and then refreeze it for another week.
Rice weevils are usually found in grain storage facilities or processing plants, infesting wheat, oats, rye, barley, rice, and corn. Although not often found in the home, they are sometimes found infesting beans, birdseed, sunflower seeds, dried corn, and too a lesser degree macaroni and spaghetti. Rice weevils do not bite, nor do they damage wood or furniture.
Adult weevils are about 3/32 to 1/8 inch long (2-3mm). The adult rice weevil is a dull reddish-brown to black with round or irregularly shaped pits on the thorax and four light reddish or yellowish spots on the elytra (wing covers). The adult weevil can fly and is attracted to lights. The larval stage is legless, humpbacked, white to creamy white, with a small tan head. The maize weevil is very similar to the rice weevil, but larger.
The adult granary weevil is a somewhat cylindrical beetle about two-tenths of an inch (two to three mm) long. The head is prolonged with a distinct snout extending downward from the head for a distance of about one-fourth the length of the body. The weevil is polished red brown to black with ridged wing-covers and a well-marked thorax with oval pits. The granary weevil does not have any spots like the rice weevile does. Unlike the rice and maize weevils, the granary weevil cannot fly. The egg hatches in a few days into a soft, white, legless, fleshy grub which feeds on the interior of the grain kernel. The grub changes to a naked white pupa and later emerges as an adult beetle.
The cigarette beetle and the drugstore beetle closely resemble one another, but the cigarette beetle is the more common of the two. Both beetles have a "hump-backed" appearance.
Both beetles are about 1/8 inch long, cylindrical, and uniformly light brown.
The wing covers of the drugstore beetle have longitudinal grooves, while those of the cigarette beetle are smooth.
Also the body hairs of the cigarette beetles are considerably longer, giving it a more "fuzzy" appearance.
The cigarette beetle feeds on cured tobacco, cigarettes, and cigars. It may be a serious pest of items such as books, flax, cottonseed meal, cereals, and cereal products, animal products, wool, rice, ginger, pepper, paprika, dried fish, seeds, and dried plants.
In the home this beetle is most commonly found in pet foods, cereals, nuts, and candy.
Rhyzopertha Dominica, or Grain Borer, is one of the smallest of the grain-infesting beetles, but one of the most important. Originally native to the tropics, it has spread through commerce to all parts of the world. It is most prominent in the United States, southern Canada, Argentina, India, and Australia. In the United States, it is particularly widespread in the Gulf states.
Both adults and larvae feed within the interiors of nearly all grains, including rice, and the kernels are reduced to mere shells, hence it is a hidden infestation until the adults are apparent.
The adult is about 3 mm long, polished dark brown or black, and has a somewhat roughened surface. The lesser grain beetle is almost cylindrical, and the head cannot be seen from above. Likewise, this insect, though small, has powerful jaws with which it can bore directly into wood. Wood may have been its original food. It can eat its way into wooden and paper boxes, and may destroy book bindings.
The Indian meal moth, Plodia interpunctella (Hübner), is a very common household pest, feeding principally on stored food products. In fact, it has been called the most important pest of stored products that is commonly found in the home or in grocery stores in the United States.
The larvae are general feeders, as they can be found in grain products, seeds, dried fruit, dog food, and spices. The Indian meal moth received its common name from the United States where it was found to be a pest of meal made of "Indian corn" or maize.
This insect is found in a wide range of climates in stored products and food storage facilities around the world. It is very common in Florida, where it also lives successfully out-of-doors.
Adults are a common sign of an infestation. When flying adults often appear to be fluttering instead of maintaining a direct line of flight. They are attracted to light and may move to distant rooms in the house away from the infestation. As a result, they are also commonly mistaken for clothing pests. Adults do not feed.
Tribolium castaneum, or Red Flour Beetle (Left) and Tribolium confusum, or Confused Flour Beetle (Right), known as "bran bugs," primarily attack milled grain products, such as flour and cereals. Both adults and larvae feed on grain dust and broken kernels, but not the undamaged whole grain kernels.
These beetles often hitchhike into the home in infested flour and can multiply into large populations. Some survive on food accumulations in cabinet cracks, crevices, and furniture.
Confused flour beetles are the most abundant and injurious insect pest of flour mills in the United States. Badly infested flour is characterized by a sharp odor and moldy flavor.
They do not bite or sting humans or pets, spread disease, or feed on or damage the house or furniture.
Both the confused and red flour beetles are similar in appearance. They measure about 1/8-inch long and are flat, shiny, reddish-brown, and elongated.
The adult is a small buff to yellowish-brown moth about one-third inch long with a wing span of one-half inch. The front wing is a lighter color than the hind wing. Both wings end in a thumb-like projection and have fringed rear margins. The eggs are white when first deposited, but soon turn red. Full grown larvae are one-fifth inch long and white with a yellow head. The area near the head is slightly larger in diameter than the posterior portion of the insect.