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Identification and Biology
The Indian meal moth (Plodia interpunctella) is the top most common food-infesting moth found in schools, homes, grocery stores and any place where dried pet foods are produced or stored. It feeds on a large variety of stored food products, but infestations often are started through dried pet food or birdseed. Nuts are a favorite breeding source; infestations have been found in nut caches of squirrels in attics and chimneys.
The larva prefers coarse grades of flour, whole grains, cereal, dried fruits, seeds and spices. Foods infested with these insects will have the larva's silk webbing present; look to find it at or near the food surface. Adult moths are about 1/2-inch long and have distinctive wing markings. The base of the forewing is pale grey and the outer two thirds is reddish-brown with a coppery luster. They have a unique way of folding their wings while 'resting' at an angle against a wall. The larvae are generally creamy-white with shades of yellow, pink, brown or green. Mature larvae, which are about 1/2-inch long, usually move away from the feeding site and spin a silk cocoon in which to pupate.
The Demestid family are common pests that scavenge and feed on animal matter like dried meats, dead insects, hides and woolens. The species that feed on wool and other natural fibers or blends are sometimes called carpet beetles. Closely related species, such as the warehouse beetle, varied carpet beetle and larder beetle have adapted for other foods and now also feed on grain and grain-based products. They are especially common in flour and cereals but also are found in candy, cocoa, cookies, corn meal, nuts, pasta, dried spices, and many other dry foods.
Usually only larvae can be found in infested food. After pupating, the adults will leave the food to feed on pollen. Sometimes only the larval “skins’ will be found. Dead adults are often found in windowsills because they fly to the light, trying to get outside.
Since some of these species feed on woolens and cloth, infestations in the pantry may spread and damage valuable clothing and furs. Proper cleaning and storage of woolen and cloth products will help prevent damage.
Sawtoothed Grain Beetle (Oryzaephilus surinamensisis) is another very common pantry pest. It does not feed on intact whole grains but feeds on many processed food products. This may include breakfast food, dried fruits, nuts, sugar, chocolate, and macaroni. It especially likes to eat oatmeal and birdseed. Their flattened body gives them the abiliy to get into sealed boxes.
Sawtoothed Grain Beetle
Cigarette beetles (Lasioderma serricorne) and Drugstore Beetles (Stegobium paniceumare) small, stout beetles are common in kitchens where they will eat cereals, spices, and other packaged foods. Since they closely resemble each other, they are often confused. The heads of both beetles are tucked under the prothorax and are not visible from above. Both are brown and about the same size.
The two beetles can be distinguished by their wing
covers. The wing covers of the drugstore beetle have
rows of longitudinal grooves while those of the
cigarette beetle are smooth. Another distinguishing
feature is the antenna. The drugstore beetle has a
three-segmented club while the cigarette beetle has
an antenna that looks a little like a saw blade.
Both the cigarette and drugstore beetles belong to the
family Anobiidae and can be confused with some
wood-boring beetles of the same family. It is
important to have the beetle identified because woodboring
beetles have greater damage potential than the
cigarette and drugstore beetle. However, if the
Other pantry pests:
Flour Beetles (Tribolium spp) contain many species of tiny beetles that infest flour, but the two most common flour beetles are the confused and red flour beetles. These beetles are scavengers because they must wait for other insects to damage grain kernals before they can attack. In schools, they can be found feeding on flour, cracked grains, cake mixes, beans, peas, dried fruits, nuts, chocolate, and spices.
They can be told apart by inspecting the antennae. On the red flour beetle, the antennae has three-segmented club on the end. The antenna of the confused flour beetle gradually enlarges toward the tip, ending in a four-segmented club. In addition, the sides of the red flour beetle’s thorax are curved while the confused flour beetles thorax has straighter sides.
Granary and Rice Weevils (Sitophilus spp) damage whole grains or seeds. They
do not usually feed on flour or cereals unless it has
Grain Mites (Acarus siro) are pests of food products like cereals, dried vegetable materials, cheese, corn and dried fruits. These mites are often found in conjunction with fungal growth- this is because they reproduce quickly in habitats with high humidity. Severe infestations result in brownish tinge over the commodity, called “mite dust” because of the light brown coloring of the mite legs. This “mite dust” gives off a “minty” odor if the mites are crushed. The life cycle from egg to adult takes only about two weeks at normal room temperatures. Mites will migrate to other food sources in times of overcrowding.
The following tips may be useful.
Infested items can be salvaged by freezing three to four days or by being heated in a 140ºF oven for an hour. Empty and thoroughly vacuum cupboards or shelves holding infested food items, paying attention to cracks and corners. Vacuuming picks up hiding insects and spilled or infested material. To prevent reinfestation, empty the vacuum cleaner or discard the vacuum cleaner bag after use.
Do not use insecticides for controlling these or other
insects in pantry areas. Washing shelves with
detergent, bleach, ammonia or disinfectants will not
have any effect on these pests since these insects lay their eggs on suitable food. Removing infested items
Information from this page can be found on the University of Nebraska "School IPM How- To Manual". The PDF of the Pantry Pests chapter, with additional information, can be accessed here: IPM Pantry Pests
Carpet Beetles (GotPests.org)
Flour Beetles (GotPests.org)
Indian Meal Moth (GotPests.org)
Larder Beetle (GotPests.org)
Sawtoothed and other Grain Beetles (GotPests.org)
Whitney Cranshaw, Colorado State University, Bugwood.org
Clemson University, USDA Cooperative Extension Slide Series, Bugwood.org
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