Indian meal moths come into the home with infested products. The female Indian meal moth will lay her eggs near a food source, and when eggs hatch, larvae crawl into the food product via holes in packaging. These moths do not destroy clothing or fabrics, but will damage stored food products with their mass amounts of webbing, fecal pellets, and shed exoskeletons.
One of the most common sources of Indian meal moths is wild bird seed. The grains and seeds are infested with larvae in the store, but homeowners do not realize it until after the moths emerge and infest other products in the home.
Identification and Biology
Immature Indian meal moths are caterpillars that have a distinctly dark head capsule, three pairs of thoracic legs and five pairs of prolegs on the abdomen. Indian meal moth larvae are mistaken for maggots (immature flies). Maggots lack a head capsule, are completely legless and do not thrive in dried goods.
Indian meal moth larvae have chewing mouthparts, which allows them to gain access into unopened packages of food. During its larval form, it can appear to be yellowish, greenish, or pinkish in color depending on its food source. It eats, grows and molts five times, growing up to 5/8-inch before it travels out of the product, leaving silken threads where it will pupate.
When adult moths emerge from cocoons, they are 1/2-inch long with a wingspan of 3/4-inch. They can be distinguished from other moths by their two-toned markings on their wings, which are whitish-gray closest to the head and reddish-brown with a copper luster on the end of the forewings. Adult moths are short-lived and do not feed. The larvae do all the damage to food.
- Females lay 200-400 eggs.
- Eggs hatch in 3-5 days (depending on temperature).
- Larvae feed and mature in 21-30 days (depending in food quality, temperature, humidity)
- Pupation occurs away from infested materials in silk webbing.
- Adults emerge from pupa in 7-10 days.
Signs of Infestation
- Adult moths flying around inside the house, usually attracted to lights, fluttering around screens at night.
- Silken threads and webbing on/ in food products, packaging, storage shelving, cupboards, walls, and ceilings.
- Larvae crawling in the food products that contain flour, cereal, stored grains, chocolate, nuts, or dried fruits.
Management of Pantry Moths
Treatment strategies for Indian meal moth, if caught early, do not include insecticide use inside the home. Because many infestations are in kitchen pantries, insecticide exposure to food products would be a risk to human health. A thorough inspection is necessary to locate and eliminate the source of the infestation. Most people overlook prepackaged and prepared foods, unopened packages, and non-food items, but a variety of products are vulnerable to Indian meal moths. Once the infested product is located, it can be bagged, put in the deep freezer until trash day, or taken immediately to an outside trash receptacle.
Infested pantries should be cleared of all food products, vacuumed, and wiped down to remove webbing and pupae hiding in cracks and crevices. Commercial pheromone traps can be used to capture adult male moths, but female moths are not attracted to it and can continue to mate and lay eggs. These traps are better monitoring tools than a form of control.
In severe situations that warrant an insecticidal crack and crevice treatment, read, and follow all instructions on the label.
Prevention and Sanitation
Here are ways you can prevent infestations in the home, minimize wasted food and save money:
- Before purchase, check for rips or tears in packaging and other signs of infestations.
- Avoid buying in bulk and storing enormous quantities of products in the pantry.
- Keep wild bird seeds in the garage or shed in an airtight container.
- Store human and pet food products in airtight, insect-proof containers.
- Use the oldest products first to ensure freshness and proper stock rotation.
- Store infrequently used products in the refrigerator or freezer.
- Clean-up spills and crumbs in food storage areas so not to attract pests.
- Vacuum cracks and crevices where insects can hide, and grains can accumulate.
- Infested non-food items to inspect include dried flowers, museum specimens, spices, and dog biscuits.
- Indian meal moth has been known to infest candy bars and baked goods in vending machines.
- Take care of rodent problems early. Mice will store food in caches near nests, and the caches can become infested. In addition, the bait block rodenticides are made with seeds, which can also become infested by pantry moths. The best way to eliminate mice is by trapping them with snap traps, followed by exclusion techniques.
It is important to keep in mind that infestations of Indian meal moths may take 6 to 12 months to get under control. Even after all infested food products are thrown away, adult moths can continue to emerge from hidden cocoons in furniture, corrugated cardboard, containers, appliances, textiles, curtains, walls, ceilings, and anywhere and everywhere.
All photos taken by J. Green who has experienced an eight month pantry moth infestation.