Pest Identification And Information

Indian Meal Moths

The Indian Meal Moth is the most important and common pest of stored products found in homes, grocery stores, food processing plants, grain storage facilities, etc. in the United States. They were named by an early American entomologist who found them feeding on corn meal (Indian meal).

FACTS:

• Adults are most active in the early evening.

IDENTIFICATION:

Adults, when at rest, are about 3/8-inch long.  They have a 5/8 to 3/4-inch wingspan. The wings are a burnished copper, almost purple with a broad gray band near where they attach to the body. The mature larvae are about 1/2-inch long and dirty white, pink brown, or light green. The head and top of the first body segment behind the head are reddish brown, yellowish brown depending on its food.

INDIAN MEAL MOTH OR CLOTHES MOTH?:

Indian meal moth larvae will have five or six ocelli (eyespots) on each side of the head; Clothes moth larvae have either one pair or none.

BIOLOGY:

• Complete metamorphosis (egg, larvae, pupa, adult).
• Females will lay between 39 - 409 eggs, with 128 being the average.
• Incubation period is 2 to 17 days.
• Their preferred temperature range for development is 79 to 84 degrees F.
• Larvae will mature in about 5 weeks.
• Larvae do the damage by eating in and on infested foods.
• Larvae will produce a silk like "webbing" material throughout the infested areas and products.  Food materials may be completely matted with this webbing if the infestation is heavy.
• Larvae are very hard and are very resistant to cold temperatures.
• When the larvae pupate, they will move away from the infested products and pupate along ceiling/wall joints, on top of and under cabinets and shelves, in the folds of cardboard boxes or cartons, and nearby cracks and crevices.  The homeowner generally notices they have a problem at this time.
• The pupal stage lasts about two weeks.
• Adults begin mating almost immediately after emerging from the pupal state.
• Adults live a relatively short period of time and cause no damage.  They simply mate, lay eggs, and die.
• An entire life cycle can be completed within four weeks under favorable conditions.

HABITS:

The adults cause no damage. The larvae are surface feeders and generally produce a lot of webbing throughout the infested part of materials. They are general feeders and attack grain and grain materials, a wide variety of dried fruits, seeds, nuts, graham crackers, powdered milk, biscuits, chocolate, candies, pancake mix, pasta, cake mix, dried red peppers, dry dog/cat food, bird seed, etc. They are very destructive wherever dried fruits are stored. Preferred are the coarser grades of flour such as whole wheat, graham flour, and cornmeal, but they can breed in shelled or ear corn.

The adults, when flying, fly in an irregular, zig zag pattern.  They are chiefly night flyers, becoming most active at dusk. During the day, they prefer to rest on walls, ceilings, boxes etc. in poorly lighted areas.  Adults are attracted to light, resting on walls and ceilings, can be attracted to TV's.

They are frequently confused with clothes moths, especially when the larvae are wandering about looking for pupation sites.

TREATMENT:

To prevent and control Indian Meal Moths, follow this six-step process.

Consists of a six-step process: prevention, good sanitation, proper storage, stock rotation, ventilation, and control.

Inspection:  Inspect all suspected materials before storing or placing into cupboards.

Sanitation:  Remove and clean up as soon as possible any and all spilled products. Out of the way areas where children may spill or leave food materials needs to be checked (may require some detective work!).

Storage:  If at all possible foodstuffs need to be stored in “cool” cabinets, avoid storing susceptible products in cabinets next to or above the stove and refrigerator. Transferring products that are packaged in paper, cardboard, or plastic bags into tight sealing containers such as Tupperware, Rubbermaid, etc.

Rotation:  Do not store large amounts of susceptible products, rotate older products out. Food should not be kept or stored for more then two months (if kept in cold storage, you can store it longer). Plan your menu to use up older products.

Ventilation:  Proper ventilation is important to reduce or keep food moisture content low.

Control:  Usually, some sort of chemical control is needed to control these pests. After cleaning out the cabinets, a vacuum cleaner or synergized pyrethroid aerosol should be used to remove/kill any exposed stages and webbing. The cabinets should then be cleaned/washed out, paying close attention to cracks and crevices.  An appropriately labeled residual insecticide can now be applied according to the label.  Keep in mind that the larvae which are in pupation have moved away from the food source so treating cracks, crevices and other such hiding spots away from the cabinets proper, is necessary.  Aerosol or fogging treatments are recommended to control the adults, although this will not solve the infestation problem.