The pantry moth, commonly called the Indian meal moth, is a food-infesting insect often found in homes and grocery stores. The pests tend to gain entry into homes from packaged foods like wheat flours and cereal grains. The most widely distributed of all moths, the Indian meal month has a global presence and remains a common pest of New England homes. The pantry moth can contaminate food as well as cause distrust in the quality of a food supplier.
Appearance & Identification
What does a pantry moth look like?
Simple to identify, pantry moths feature copper or bronze-colored scales on the outer two-thirds of the forewings. The rest of the body appears whitish-gray in color. Small in comparison to other moths, pantry moths usually measure about 3/8 of an inch in length with wingspans measuring over half an inch. Larvae appear dirty-white in color. The developing young also referred to as caterpillars, exhibit sets of legs near the head and five sets of prolegs along the abdomen. As larvae grow, they develop yellow, green, or pinkish tints. Fully grown pantry moth larvae usually measure about 5/8 of an inch in length.
In nature, pantry moths live during the warmer months and feed on seeds and decaying fruit. Industrialized food production created an ideal habitat for Indian meal moths, allowing easy access to food, shelter, and indoor temperatures that allows for year-round reproduction. Pantry moths commonly sneak into food production and storage facilities and may end up in grocery stores and homes when packaged in with food. Home infestations come from a wide array of food sources but most commonly originate from dried pet food and bird seed. The insects may also enter the home when living off of nuts in nearby rodent or squirrel nests. Adults usually fly into homes through open doors, windows, gaps, or crevices leading into the home. Like many moths, adult pantry moths rest during the day and fly toward light at night. The flight pattern of a pantry moth appears more like lingering fluttering than a direct path, which makes adults easy to spot in the home.
What does a pantry moth eat?
Indian meal moths (larvae) prefer to eat stored foods such as grains, seeds, dry dog food, nuts, and dried fruits. Coarsely ground grains, like corn meal, graham flour, and whole wheat, remain the most common products the insects feed on. Pantry moths also seem to favor cereal products and dried fruit, especially figs.
Females lay eggs on and around food sources so larvae have easy access to nourishment upon hatching. Depending on such environmental conditions as temperature and food quality, eggs can hatch in as little as two days or as long as two weeks. Eggs are small and difficult to see with the naked eye, with newly hatched larvae equally difficult to spot. The pest’s small size early on allows it to pass through industrial screening, which explains why pantry moths can end up in packaged food and grains at the grocery store. Pantry moths spend the majority of their lives in the larval stage, which can last as little as two weeks and as long as a year, depending on the environment. During the larval stage, the developing insects grow as they feed on grain and eventually spin themselves into silken cocoons to pupate. Environmental conditions also affect this developmental stage, and adults may emerge from cocoons within four days or up to a month. Within a day of reaching adulthood, females have mated and begin producing and laying eggs. Adults have short lifespans that usually last about a week or two. Pantry moths breeding in grain bins or buildings with stored grains that often maintain warm temperatures year-round allows up to as many as nine generations of pantry moth per year.
Problems Caused by Pantry Moths
Pantry moths contaminate food by leaving behind excrement and cast skins. Webbing produced by larvae also affects the odor and taste of food. In addition to causing health concerns, the insects leave an economic impact by reducing grain output. The sight of webbing or pantry moths themselves are usually enough to ruin appetites and cause foodstuffs to be discarded.
Signs of Infestation
Finding larvae and adult pantry moths around food-storage areas clearly indicates an infestation. The pests can also be found elsewhere in a structure, as adults may travel away from food sources. This often causes untrained individuals to misidentify the invading pest as another species of moth. To be sure about the infesting species, look for the copper color on the outer portions of the wings to ensure it is an Indian meal moth. Finding the silken material larvae use for cocoons also serves as a key indicator of a pantry moth infestation. Larvae usually produce excess amounts of the threads, which may appear as loose strands or matted and clumped with food matter. Cocoons for pantry moths in the pupal stage may appear on food surfaces or clinging to the insides of containers. Often, larvae about to reach the pupal stage travel a short distance away from the stored food to pupate, so cocoons may be found on the outside of containers or on pantry walls.
Individuals should keep foods in tightly sealed containers to prevent pantry moths from infesting the home. Plastic or glass containers work best, as larvae can chew through thin cardboard and light plastic bags. Homeowners often overlook dog food and bird seed, which pantry moths commonly infest due to careless storing. Bags must remain shut when not in use, and foods packaged in thin, easily torn plastic should be placed in sturdier containers. Cleaning up loose food materials that may accumulate in pantries also cuts down on the likelihood of attracting the pests. If moths or signs of pantry moth presence are found in a container of food, discard the contents of the container and check nearby food for signs of the moths.