Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Pyralidae
Genus: Plodia
Species: P. interpunctella
Binomial Name: Plodia interpunctella (Hübner, 1813)

The Indian meal moth originated in the Old World, but now occurs around the world. Plodia interpunctella is found on every continent in tropical habitats, excluding Antarctica.[1] Within the United States, the moth is most commonly found in Florida, where it thrives in the tropical habitat.[1] The moth lives in a wide range of conditions, making it a persistent pest. It is often found at food storage facilities worldwide, specifically in grain bins or grain storage buildings.[1]

Host Range
Indian-meal moths feed on plants, grains, and other human food products. The Moths feed on many plant-based foods including dry pet food (plant based), birdseed, cereal, soup mixes, bread, pasta, rice, flour, spices, dried fruits and nuts. Other optimal diets include sultanas, American yellow corn and almonds. Groundnuts and maize meal, on the other hand, result in a longer development time for the moths.[1]
Indian-meal moths are also known to cannibalize larvae but this often leads to viral Granulosis infections spreading through an Indian-meal moth population. Healthy larvae are picked more often than unhealthy larvae for cannibalism.[1] There appears to be no kin discrimination and siblings can be eaten by caterpillars.[1]

Egg: The eggs of the Indian-meal moth are white, ovate, and very small. It is difficult to see them with the naked eye. 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.
Larva: Newly hatched larvae are equally difficult to see. They are mostly off-white in color, have brown heads, and develop through five to seven larval instars. When these larvae mature, they measure about 12–14 millimetres (15⁄32–9⁄16 in) long. Larvae also have three sets of legs near the head and five sets of prolegs protruding from the abdomen. The legs help the larvae move over long distances in order to find pupation sites.[1] There are five to seven larval instars. Their color is usually off-white, but has been observed to be pink, brown or almost greenish, depending on the food source. The mature larvae are about 1/2 inch (1.27 cm) in length. They have five pairs of well-developed prolegs that help them move considerable distances to pupate.
Pupa: The larvae pupate either in a silken cocoon or unprotected. The pupae are 1/4 to 2/5 inch long (6 to 11 mm) and are pale brown in color. Pupation takes place away from the infested material. In fact, late instar larvae can travel such distances that they are often mistaken for clothing pests. Within the pantry, small larvae often climb to other shelves before pupating. This misleads people trying to find the source of the infestation.
Adult: Adults are about 1/2 inch (12.7 mm) long with a wingspan of about 5/8 inch (16 to 20 mm). The distal two thirds of their forewings are generally reddish brown in color with a copper luster. They can also be bronze or dark gray. The more proximal parts of the wings are yellow-gray or white-gray, with a dark band at the intersection between the proximal and distal regions. The hindwings, in general, are uniformly gray.[1] Adults are a common sign of an infestation. 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. However, even though not necessary for egg production, adults have been reported to be interested in fruit juice and sugar baits (Kullberg, personal communication). 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.

The almond moth (Cadra cautella) and the raisin moth (Cadra figulilella) are commonly confused with the Indian-meal moth due to similar food sources and appearance. The species was named for feeding on Indian meal or cornmeal, and does not occur natively in India. It is also not to be confused with the Mediterranean flour moth (Ephestia kuehniella), another common pest of stored grains.

Indian-meal moths are known to mate multiple times. For males, it is vital to ensure paternity after copulation. To ensure this trait, males who mate with a female first (before any other males) will insert a large package of spermatophore, accessory gland fluids, and nutrients into the bursa copulatrix of the female during copulation. Other donations after the first mating are smaller in size. Even so, there is no change in postcopulatory behavior in females after this large donation (with respect to pheromone production and calling behavior).[1]
Though Indian-meal moths generally do not migrate over long distances, they do engage in long-distance foraging flights. These flights take place during the twilight hours during which blue light (400–475 nm) rather than UV light (10–400 nm) is dominant and attracts the moths. Blue light’s role in the Indian-meal moth foraging behavior has recently been harnessed as a form of pest control since it is attractive to the moth.[1]
All moths have four life stages: egg, larva, pupa, and adult. The larvae develop in many different stored foods such as coarsely ground grains, cereals, dried herbs, dried fruits, and nuts. These moths can also feed on pet foods such as flaked fish food, bird seed, and dried dog or cat food. Ornamental items made of dried flowers or seeds can also serve as breeding sites for these moths.
The moths tend to fly from dusk through the night. Eggs are laid on or near suitable food items. Upon hatching, caterpillars begin seeking out food items for their development. While feeding, they produce silk that loosely binds fragments of food. The caterpillars tend to remain concentrated on the surface of large undisturbed containers. The caterpillars can chew through thin cardboard or plastic bags, and can be found in small, loose food packages.
Caterpillars can reach maturity in as little as one month, depending on food quality and temperature, though the development time is typically much longer. Mature caterpillars migrate away from the food source to pupate, forming cocoons in cracks or confined spaces between walls or in the ceiling.
After emerging from the puparium, the adults mate and females can lay over 200 eggs in or near suitable food sources. The adults survive about a week since they do not feed. Several generations are completed annually in Colorado homes, and all life stages may be present since generations overlap. Adults are observed most frequently in the fall and winter.

A life cycle can be completed in 27 to 305 days. A single female can lay up to 400 eggs after mating. The mating and laying of eggs occurs about three days after adult emergence. The eggs can be laid singly or in clusters, and are generally oviposited directly on the larval food source. The eggs hatch in seven to eight days at 20°C and three to four days at 30°C. Upon hatching, the larvae begin to disperse and within a few hours can establish themselves in a food source. The larvae can complete their development in six to eight weeks at temperatures from 18 to 35°C. The number of larval instars varies from five to seven (depending on the food source and the temperature). The pupal stage can last from 15 to 20 days at 20°C and seven to eight days at 30°C.
The female moth begins to lay eggs about 3 days after becoming an adult and deposits 200-300 eggs over 1-18 days. Because of the large number of eggs, it doesn’t take long to get a sizable infestation that destroys large quantities of food.
Eggs are laid singly or in groups, directly on food. Eggs hatch in 7-8 days. Larvae feed for 6-8 weeks protected in or near a tunnel-like case of frass and silk they weave together. Just before the larva pupates, it may travel a considerable distance to a location away from its food source. They can penetrate packaging materials or even a polythene film. The pupal stage lasts 15-20 days.
Eggs: Usually the life cycle of an Indian-meal moth colony starts in a location where grain is present. The temperature within a grain bin must exceed 50 °F (10 °C). The eggs of the moth are grayish white and have a length between 0.3 and 0.5 millimeters (1⁄64 and 3⁄128 in). Eggs can be laid directly on the food source singly or in groups of between 12 and 30. A mature female may lay between 100 and 300 eggs at a time.[1]
Larvae: Larvae begin to hatch in approximately two to fourteen days. The larvae have between five and seven instars. Newly hatched larvae feed on grain while more mature larvae feed on grain germ. The larvae are an off-white color, but can be pink, brown, or greenish. They are about 12 mm long and have prolegs for movement. Fully-grown larvae are able to spin webs and leave silk threads in their path of travel. Mature larvae that make silk also make threaded cocoons.[1]
Adults:The pupae are often seen on grain surfaces and on the walls of grain bins. The adults emerge in four to ten days. They then mate and the cycle begins again.[1] The entire life cycle of this species ranges between 30 and 300 days. A typical life cycle is 50 days. Under optimal conditions a life cycle can be as short as 28 days but cooler winter months prohibit this. Seven to nine generations of moths can live in a year.[1]
Diapause: Diapause is defined as a delay in animal development due to certain external factors[1] and can end once the adverse environmental conditions wear off. The duration of diapause can vary in Indian-meal moths. Diapause is especially prevalent late in the breeding season. During the egg stage, if the temperature of the moth’s environment exceeds 25 °C (77 °F), it can cause a delay in hatching. In the moth’s early larval stage, temperatures of below 20 °C (68 °F) can cause a similar diapause. Different strains of P. interpunctella have differing tendencies to enter diapause.[1]

In a nutshell, the life cycle includes:
As long as the temperature within a grain bin or building where grain is stored remains above 50×F, the Indian meal moth can survive and reproduce. A typical life cycle (egg to adult) is completed in forth to fifty-five days. A potential for seven to nine generations per year exists; however, because of cool temperatures during the winter months fewer generations are
A mature female lays 100 to 300 eggs on food material, either singularly or in groups of twelve to thirty. Larvae begin to hatch in two to fourteen days, depending on environmental conditions. Newly hatched larvae feed on fine materials within the grain and are small enough to pass through a sixty mesh screen. For this reason, it is difficult to exclude larvae from most packaged foods and grain.
The life cycle and habits of this pantry pest is similar to other moths infesting stored products. Eggs are laid on or near the food. A female moth may deposit from 40 to 350 eggs. After hatching, the small caterpillars begin spinning silken threads in the infested food material. They feed for about two weeks before becoming full grown. They crawl up to the surface of the food material or often up walls and pupate within a cocoon. The adult emerges in about 30 days. The entire cycle requires about six weeks and there are from 4-6 generations per year

Most of the damage to stored products occurs when the larvae spin massive amounts of silk that accumulate fecal pellets, cast skins, and egg shells in food products. The damage to stored products due to this contamination exceeds the amount of food eaten by the insects. In large grain stores feeding is concentrated at the surface as the larvae do not burrow much.

Finding webbing or a large number of caterpillars or worm-like larva (immature insect stage) crawling about in a box or container of cereal or spices is often the first indication of an infestation. Also, moths flying around the kitchen or an enclosed area such as a garage is a sign that you should inspect grain products, cereals, spices, dry pet food, and birdseed.
The presence of webbing, frass (excrement), cast skins, pupal cases and dead adult moths on food surface is a major indication of infestation.

The Indianmeal moth is one of the most common and troublesome of moths infesting stored food products. The caterpillars cause all of the damage. The larvae infest a wide variety of food products, especially those of plant origin. They have been found in stored grains, flour, cornmeal, nuts, dried fruits, powdered milk, candy, chili pepper, fish food, dry dog and cat food, seeds, and chocolate.

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Sanitation: It is recommended to first eliminate the source of infestation followed by larvae, eggs, and eventually moths. After larvae or moths have been found, it is important to throw out all food sources not in very tightly sealed containers. Moth larvae can chew through plastic bags and thin cardboard, so even unopened packages may become infested.[1] They are also notoriously difficult to get rid of, and can crawl on ceilings and spin cocoons in rooms other than where they hatched. Last instar larvae are able to travel significant distances before they pupate. 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 signs of infestation, otherwise the infestation 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 advisable in warmer areas to keep meals and flours under refrigeration until used, this precaution is not always followed by homeowners and others.
None of the stages of the organism (eggs, larvae, adults) are temperature tolerant and can be killed by a week of freezing or by brief heating in a microwave or conventional oven when such treatment is practical.[1]
Scrubbing infested areas with a mixture of soap and water or vinegar is also effective.[1]
Nontoxic traps are available to monitor outbreaks. One type of trap is a triangular box with a pheromone lure and sticky walls inside. These traps are known as pheromone traps. Male moths are attracted by the female pheromone (the lure) and stick against the sticky walls inside the box.[1]
The caterpillars are parasitized by Habrobracon hebetor, a braconid wasp which is a potential biological control agent.[1]
Additionally, blue to violet light can be very effective in drawing moths out, which suggests that the deployment of violet light could become another pest control tactic for these moths.[1]
Freezing and Heating: If an infestation is detected, freezing the product for several days has proven to be an effective control measure. Infested products should be kept in temperatures of 0°F (-18°C) until the cold penerates all areas of the packaging. Four days should kill the life stages of most stored product pests. Heat will also kill stored product pests if temperatures of 130°F to 150°F (54°C to 66°C) are maintained for 24 hours in infested facilities. Small quantities of infested materials can be treated in their original packaging or the loose material may be placed in a shallow pan. Then heat the material for 150°F (66°C) for 20 minutes. However, one reference advises propping the oven door open to keep it from getting too hot (Mallis 2004).

Prevention is the best control for pantry pests. This may include the following:
When purchasing bulk grains, dried fruit, flour, etc., inspect it carefully when loading it into bags for weighing. Inspect products again when you get it home and put it into storage containers.
Keep food in glass jars, plastic containers, or metal canisters. Glass jars that pressure seal with rubber gaskets are the best. Make sure they have tight-fitting lids. Many of the pantry pests are very small and can crawl under loose-fitting lids. Do not store products in plastic bags, or cardboard boxes as the insects can chew through them.
Try to store foods in a cool dry place. Most of the stored product pests multiply faster at higher humidity. Many products can be kept in the freezer to prevent infestation, especially products that are not used right away. Nuts, flours, meals, and dried chili peppers can all be frozen.
Infested foods should be thrown away and the shelves cleaned thoroughly to eliminate food material and insect eggs or larvae which might be in cracks or corners.
Vacuum the shelves and then wash the cupboards with warm soapy water. Do not spray any food storage areas with insecticides. Clean up any food spills promptly.
Identifying all sources of an infestation is the most critical step in managing Indian meal moths. Any infested material should be disposed of, used, or treated with heat or cold to kill eggs and larvae. For cold treatment, place infested materials in the freezer for two or three days. Heating to 120-140 °F for 20 minutes can kill Indian meal moth but may also damage the infested item. For larger items, longer exposure may be necessary.
Cleaning thoroughly is very important to remove food for surviving insects and prevent reinfestation. Elimination and exclusion are key elements in controlling pest populations of this Moth. If a population is discovered, all infested material should be either discarded or treated. Any susceptible food source should be placed in sealed containers. In most cases, infested materials, especially small amounts, should be discarded and removed quickly from the premises. The severity of an Indian meal moth infestation can be reduced by good store hygiene which includes cleaning the store between harvests, immersing grain sacks in boiling water and fumigating the store to eliminate residual infestations and the selection of only uninfested material for storage.

NATURAL ENEMIES
Habrobracon hebetor is a parasitoid wasp that is commonly used in biological control. A biological control involves the use of other organisms to control pests. The gut enzymes released by this parasite into the Indian-meal moth larvae denature blood proteins and digest it. This, along with the larvae eating the moth, leads to its death.[1]
Other natural enemies of this pest include nocturnal insectivores (birds, bats, and owls), Lizards (Lacertilia), Bears (Ursidae), Cats (Felis catus), Dogs (Canis familiaris), Rodents (Rodentia), Spiders (Arachnida), Humans (Homo Sapien), and other cannibalistic Indian-meal moths[1].
Population suppression has been observed in the laboratory using egg and larval parasites. Both the larval parasite, Bracon hebetor (Hymenoptera: Braconidae) and the egg parasite, Trichogramma pretiosum (Hymenoptera: Trichogrammatidae) have demonstrated moth population suppression. When the parasites were used in combination, an 84.3 percent suppression was observed. Trichogramma pretiosum acting alone offered a 37.3 percent suppression rate while Bracon hebetor provided a 66.1 percent suppression rate.
The egg parasitoid Trichogramma evanescens can be mass released to control Indian meal Moth although the authors were not able to find any information on the effectiveness of this method in storage facilities.

CONTROLLED ATMOSPHERE
Where suitable infrastructure exists, low oxygen and carbon dioxide-enriched atmospheres can be used to control stored product pests.

Freezing and Heating: Where the infrastructure exists, freezing for several days and heating for 24 hours have proved to be effective control methods for stored product pests.

Indian-meal moths are developing a resistance to many kinds of biological agents, such as the granulosis virus. Use of pest control agents can cause resistance to these agents to be selected for in populations of Indian-meal moths. In populations exposed to the granulosis virus, it was found that the moths were 96 times more resistant to the virus. This led to the prohibition of many such biological agents.[1]
Regulations prevent the use of many pesticides in food sources so these pests are highly suitable for control with natural predators.[1]

Numerous insecticides have been used to control Indianmeal moth populations, but effectiveness is limited. In a study evaluating the effectiveness of an insect growth regulator, it was found that even after treatment with these chemicals, Indianmeal moths were in corn storage bins. In an additional study using the same insect growth regulator, it was found that at rates of 5 and 10 ppm no control of fifth instar larvae was accomplished. Only at 20 to 30 ppm was control of fifth instar larvae observed. Studies show that resistance increased with increasing selective pressure. Resistance was also observed in studies performed with the microbial insecticide Bacillus thuringiensis (Bt). Resistance was just as likely with exposure to single strains of Bt as with mixtures of sequences of the insecticide. Resistance, once achieved, appeared to be inherited as a recessive trait, and with time was observed as genetically stable.
From recent study results, a couple of essential oils, especially one extracted from A. khorassanica , have potential applications for the integrated management of P. interpunctella[8].

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