Many different insects can be classified as pantry pests‚ insects that live on foods stored in the home. These insects infest products such as dried fruit, nutmeats, spices and any food made of cereal grains, such as bread, flour, cornmeal, macaroni or breakfast cereals.
The first step to control pantry pests is to locate the source of the infestation. If all insects are confined to one package, simply destroy the package eliminates the problem. If you suspect insects have invaded other packages of food, place these packages in a freezer for 4-5 days. This will kill most of them, since most kitchen pests are tropical insects by origin and are vulnerable to freezing. When insects are discovered in several packages or containers or throughout the entire cupboard, more drastic action is necessary.
Where They Come From:
Food in your cupboards may have been contaminated with insect eggs which were sealed in the package. When the eggs hatch, you can spot worms or insects in the food container. If you leave the package in the cupboard for a long time, the insects will escape and infest other foods and, eventually, the entire cupboard.
Source: W.L. Gojmerac
[Professor of Entomology]
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This cosmopolitan insect feeds on a large variety of food products. Although coarse grades of flour are preferred, Indian meal moth larvae are often found feeding in whole grains, cereal, dried fruits, nuts, seeds, and powdered milk. Foods infested with these insects will have silk webbing present, especially near the food surface.
Adult moths are nearly 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 The larvae are generally dirty-white in color with shades of yellow, pink, brown, or green, depending on its food. Mature larvae, which are about 1/2 inch long, usually move fairly long distances from the feeding site before pupating within silken cocoons. There may be 4 to 8 generations of Indian meal moths per year.
The larvae produce silken-type webbing throughout the material they’re feeding on. Mature larvae move away from infested materials to pupate in neighboring cracks and crevices. They can easily have six generations per year. Homeowners often discover these infestations when great numbers of larvae are seen moving away from infested materials, sometimes dispersing over the entire room.
Because of their habit of moving some distance from infested products, an intensive cleaning routine is necessary to find and eliminate Indian meal moths, especially in a commercial setting. Fumigations can then be necessary.
Red & Confused Flour Beetle
Click here for a photo of Red Flour Beetles
T. Castaneum and Tribolium Confusum
Adults small, dark reddish, somewhat flattened, 1/7 inch long. Red can fly while Confused cannot. Feed on wide variety of flours, cereals, debris, cocoa, fruits, and vegetable products, but not on unbroken grains. Confused and red flour beetles are serious pests in flour mills and food storage areas. Adults of both species are very similar in appearance. Larvae and adults feed on a number of foods including flour, cracked grains, cake mixes, beans, peas, dried fruits, nuts, chocolate, spices, and tobacco. Flour beetles do not feed on whole, undamaged grains. Heavily infested food products have a foul odor.
Females lay eggs on containers or in the food itself and eggs hatch in 5 to 12 days. The larvae (worm-like immature stages) are cylindrical, yellowish-white, up to 1/4 inch long, and mature in about 30 days. Pupation occurs near the surface of the food mass. There may be 4 to 5 generations per year, depending on temperature.
Link: Flour Beetle
Saw -Toothed Grain Beetle
The saw-toothed grain beetle is a common pantry, warehouse and grocery pest. The adult is flat rather narrow, and 2.5 to 3 mm (1/10 to 1/8 in.) long. Under a hand lens or binocular microscope, the beetle appears rough. and has six distinct saw teeth” on each lateral margin of the pro-thorax (behind the head). Saw-toothed beetles are quite active, although they do not fly.
Newly hatched larvae (0.80 to 0.90 mm long) are white and move slowly, but soon they become more active, darken somewhat, and commence feeding. Mature larvae are very active. rather pale yellow (with darker plates on the dorsal surfaces of the segments). Fully grown larvae are 2.5 to 2.8 mm (about 1/10 in.) long. Just before pupation. the larva usually constructs a pupa cell by cementing together particles of food, then attaches itself by its posterior end to the inner surface of the cell. At pupation the last larval “skin ‘ is shed but remains attached to the medium, and the pupa in turn remains attached to the shed skin. The pupa then is usually found inside the cell attached by its posterior end. The prothorax of the pupa has on each side six conspicuous projections which will become the saw teeth of the adult.
Eggs are laid singly or in small groups among the particles of the food medium. The eggs hatch in three to five days under optimum conditions. The number of larval instars ranges from two to five. but mostly there are three. The larva period averages 12.5 to 15 days. and the entire life cycle from the laying of the egg to adult emergence can be as short as 20 days under conditions of high temperatures and high relative humidity. In many storage conditions, a generation is completed in about a month. Considering the large number of eggs laid, populations can build rapidly. Materials Infested These insects feed on a wide variety of food products, thriving in grain in association with weevils and other insects that can damage the kernels.
Common Carpet Beetle
Photo © James Castner University of Florida
Infestations of carpet beetles in pantries are less common than flour or sawtoothed grain beetles. Carpet beetles are relatively slow to develop and require about one year for a generation on cereal products. However, since the insects are highly mobile, infestations may reoccur annually.
Carpet beetles are much more common as pests of woolens, furs and other materials of animal origin.
Link: Carpet Beetles