Do you know all of the places to look for this pest?

The Indian meal moth is the most common stored food and grain pest in the world. It’s found in grocery stores and food warehouses where it infests all kinds of packaged and bulk food products. In homes, it’s more often found infesting dry pet food and bird seed.

Identifying the Moth

Adult IMM: Size is 9 mm long with a wingspan of approximately 16 mm. The wings are gray near the base with a broad coppery band across the tips. However, on older specimens, the coloured scales may be largely worn off.

Larval IMM: Mature larva is 13 mm long and wormlike. It is whitish, but may have a pink or greenish tint. Larva is almost hairless with a brown head and five pairs of short pro-legs on the abdomen.

Indian meal Moths or Clothes Moths? There is sometimes confusion among customers and technicians as to whether the moths flying around a home are food moths or clothes moths. The number one clue is that Indian meal moths are attracted to light, clothes moths are not. IMM will fly to lights or TV screens at night while clothes moths hide from lights in cracks and crevices. Clothes moths are smaller with fringed wings and are yellowish-gold in colour, rather than having the two-tone colouration of IMM.

Where do you find IMM? Indian meal moth infestations are often first discovered when the mature larvae leave their food source and wander away looking for a protected place to pupate. They are often seen wandering up kitchen walls or across ceilings, or hanging by silken threads. They spin a silken pupal cocoon and these can be found along wall/ceiling junctions, in the corners of shelves, behind items on the walls, in the folds of boxes or bag flaps, in food processing equipment, even in the food product itself.

IMM larvae feed on a wide range of foods, including dry pet food (the No1 source), cereals, dried fruits, cornmeal, grain and whole wheat flour, powdered milk, bread, nuts, bird seed, fish food, chocolate, spices, etc. In homes, infestations usually start in those food packages that are the oldest, that are past their “use by” date, that have been damaged, or that have gotten damp or mouldy.

Your inspection should begin with older foods at the back of shelves, forgotten in corners, or stored in bulk in the garage, basement, or pantry. Almost any packaged food product, even those that are unopened, can be infested. The larvae spin silk webbing in the food as they feed. You may also find shed larval skins and droppings among the webbing.

The emerging adult moth rests during the day in dark, secluded areas and flies mostly at dusk in zigzag manner. It does not feed but will fly to lights, often in rooms away from its food source. The mated female returns to lay her eggs in food products at night.

Food Sources not in the kitchen – Indian meal moths can sometimes be found infesting items outside of the kitchen, items that don’t actually qualify as stored foods such as bean bag chairs or toys, fish or turtle food, Indian corn ornaments, horsehair furniture stuffing, jewellery or pictures made of seeds or beans, and dried flowers.

A common non-kitchen source of Indian meal moths is rodent-hoarded food. Rats, mice and squirrels collect dry pet food, bird seed, or nuts, and may store it in hidden voids in walls, ceilings, under appliances, in furniture, etc. Various stored food pests can find and infest this cached food, especially when it becomes old and damp. In this situation, rodent control needs to be part of your IMM management plan.

Indian Meal Moth Management – Commercial accounts and private residences should always practice the policy of FIFO, (“first in, first out”), so that stored foods are rotated and the oldest packages are used first. Even after the infested foods have been found and discarded, there’s the chance that female moths may have laid eggs in other food products. Any susceptible foods should be thrown out, placed in a deep freezer, or at least stored in airtight containers. Regularly cleaning up food spillage is very important.

After cleaning, kitchen and pantry shelves often need a residual treatment to kill eggs and wandering IMM. Note that treatment of food storage areas does not kill all adult IMM or larvae that have already wandered away and pupated, so a follow-up treatment may be needed in heavy infestations. Adult moths can be killed with a vacuum or space treatment.

Trapping Indian Meal Moths – Indian meal moth adults can be captured with either standard insect light traps (ILTs) or with hanging pheromone traps that contain an IMM-specific sex attractant lure. Pheromone traps are a good monitoring tool in commercial accounts and can be part of a control programme in residences.

The formidable Indian meal moth