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Pantry moths lay their eggs on stored food and grains. Finding an adult moth may be a sign that there are infested items somewhere in the home. Adult females can lay hundreds of eggs directly on or near potential food sources, and the damage is done by the larvae(tiny caterpillars). Larvae can chew through plastic bags and thin cardboard, so even unopened packages may become infested.

grain moth

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They attack a wide range of products, including cereal, grains, beans, nuts, flour, dried fruit, birdseed, dry animal food, spices, chocolate, and candies. Indian meal moth is the most common pantry moth, but properly identifying your pest will help you target your efforts. Consider contacting your local Cooperative Extension Service for help identifying a pest.

Webbing is often the first visible indication of a growing pantry moth problem. You will likely see webbing pop up in the corners of pantries and cupboards, as well as in and on bags of dried goods. Don't ignore these signs, or you may find yourself pouring a cup of flour and realizing it's filled with tiny, squirming worms.

Although the presence of pantry moths (and especially their squirming larvae) may disgust you when you find them in your stored foods, there is no indiction that these insects spread diseases in the same way that common houseflies do. They can, however, sour your baking goods with contamination if the infestation is severe.

In virtually every instance, pantry moths come into your home from purchased dry foods that were contaminated at food processing or packaging centers. Once in your home, however, they may spread to other areas of the house.

Damage by this insect is minimal in shelled corn. However, the larval stage of this insect more commonly feeds within kernels of other gains. Grain infested by the angoumois grain moth larvae has an unpleasant smell, and is less attractive for consumption.

Most problems with the angoumois grain moth in corn occur in crib-stored ears, although the infestation may have begun in the field. Corn infested in the field may harbor larvae feeding within corn kernels. When the newly harvested, infested corn is cribbed, the larvae continue to develop, pupate, and emerge as adults, which in turn deposit eggs on uninfested kernels. Several generations of the insect can be completed during prolonged warm falls, resulting in a large portion of the grain being damaged.

Female moths deposit eggs on grain kernels throughout the crib. Under normal conditions, a female will lay forty eggs. The eggs are glued to the kernel. Larvae emerging from the eggs eat through the kernel and begin feeding on the endosperm or germ. To assist in penetrating the kernel, larvae sometimes spin a cocoon that they use for leverage. Once inside the kernel, larvae continue to feed until mature, enlarging a cavity within the kernel. When mature, the larvae eat a channel to the outside of the seed, and make a weakly fastened flap at the exit by cutting the shell one-half to three-quarters the circumference of a circle. Larvae then spin silken cocoons and pupate within the kernels. Adults emerge by pushing the flap back on the kernels. The life cycle is complete in about five weeks at optimal temperatures.

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.

Angoumois grain moth larvae feed on a number of whole kernel grains. Their feeding causes a reduction in grain weight and quality. Heavily infested grain smells bad and is less attractive for consumption. Corn cribs infested with this insect will contain ears with small holes on individual kernels. Ears throughout the crib will be infested. In bins, however, only the top few inches of grain will be infested.

As with bin stored grain, sanitation and crib preparation before introduction of new grain can reduce the potential of angoumois grain moth infestations. Thoroughly clean the crib of old grain and ears. Larvae of the insect can be harbored in these residues. Harvest equipment should also be cleaned before use. Unless the ear corn is going to be stored for longer than a year, a residual insecticide is probably not necessary. Although this insect can be a serious problem, few corn cribs have populations high enough to cause concern.

While they do look like clothes moths, there are some distinctive features that make pantry moths stand out. With a wingspan of 5/8-inch, they really are rather small. Their wings have a pale greyish tint and some outer wings are more reddish brown. Connecting the upper and lower wings is a black band.

Pantry moths though small can lay up to 400 eggs at a time and hatch within a week. Once they reach the larval stage is where damage really begins to happen. Once they are at this stage of life they chew what they can. This can take up to 2-3 months until they move into cocoons. These cocoons can be found in cracks and cervices even burrow underneath the food.

After 15-20 days the moths are adults. Adult females lay hundreds of eggs directly on or nearby the food sources and the lifecycle continues again. After up to 20 days comes the adult pantry moth with its wings.

The Indianmeal 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 commonly found in American homes or grocery stores. The larvae are general feeders and can be found in grain products, seeds, dried fruit, dog food, and spices. The Indianmeal 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.

Eggs: Eggs of the Indianmeal moth appear grayish white and range in length from 0.3 to 0.5 mm. Eggs are oviposited singly or in clusters, and are generally laid directly on the larval food source.

Figure 2. Pupa of the Indianmeal moth, Plodia interpunctella (Hübner). The larva crawled up two shelves and then onto a stack of food envelopes before pupating on the inside of a military C-ration toilet-paper packet in the senior author's house. This shows how larvae have the ability to migrate to distant locations and, thus, confuse identification for the source of the infestation. Photograph by Lyle Buss, University of Florida.

Figure 3. Pupal case of the Indianmeal moth, Plodia interpunctella (Hübner). Found in the senior author's pantry, the larva pupated on the bottom edge of a soup can two shelves up from the actual infestation. All pantry goods must be examined carefully to eliminate the next generation of adults, which can fly and thus distribute the infestation further. Photograph by Lyle Buss, University of Florida.

Figure 4. Remains of a pupal case of the Indianmeal moth, Plodia interpunctella (Hübner). The larva pupated inside the lid of a cardboard container one pantry shelf up from the actual infestation in the senior author's house. This demonstrates how difficult it might be to eliminate an infestation even after it has been discovered. Photograph by Lyle Buss, University of Florida.

Figure 5. Remains of a pupal case of the Indianmeal moth, Plodia interpunctella (Hübner). The larva pupated on the side of a stack of paper cups in the senior author's kitchen. Photograph by Lyle Buss, University of Florida.

Adults are about 1/2 inch (12.7 mm) long with a wing span of about 5/8 inch (16 to 20 mm). The forewings of this moth are reddish brown with a copper sheen on the outer two thirds and gray on the inner third. At rest the wings are held roof-like over the body. The head and thorax of the moth appears gray and the posterior brown, with a coppery sheen.

Figure 7. An infestation of Indianmeal moth, Plodia interpunctella (Hübner), in a jar of pistachio nuts. It was later determined by the senior author that the nuts were purchased from a commercial supermarket that had an infestation in a bin of bulk foods. One or more infested nuts were brought home. The lid of the jar was slightly loose, which allowed several generations of Indianmeal moths to reproduce, and eventually larvae and adults escaped to pupate and spread the infestation. If the jar had been tightly closed, the infestation would have died, either from lack of air or from a buildup of moisture that would have allowed the development of fungus to destroy the larvae and adults. Observe the frass (insect fecal waste) on the outside of the nuts, as well as the webbed pupal cases in the center of the photograph. A few adults are also visible. Photograph by Lyle Buss, University of Florida.

Monitoring and sampling can be accomplished with pheromone sticky traps. In some cases of low-level infestations, traps can be used for control as well. Traps are also useful in timing and evaluation of control procedures. In a study of pheromone trap effectiveness in attracting Indianmeal moths, traps containing (Z,E)-9, 12-tetradecadien-l-yl-acetate (ZETA) proved useful in monitoring populations. One drawback of the pheromone sticky trap seems to be that population size and number trapped affect their effectiveness. For example, if large number of moths are in the trap, the ability to capture more moths decreases. The continued use of sticky traps (with pheromones) could lead to improved control programs and less incidence of insects in stored products on grocery shelves.

Sanitation: Elimination and exclusion are key elements in controlling pest populations of this moth. If a population is discovered, all infested food must either be discarded or treated. Any susceptible food source should be placed in sealed containers. Dog food and bird seed usually are overlooked as infestation sites, and these items should also be kept in sealed containers. All stored food products brought home from the grocery store should be examined for the tell-tale "white worms" and webbing, otherwise the infestion will spread to other stored products. In most cases, infested materials, especially small amounts, should be discarded and removed quickly from the premises. While it is advisible in warmer areas to keep meals and flours under refrigieration until used, this precaution is not always followed by homeowners and others. 041b061a72


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