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Pest Profile: Indianmeal Moth

The Indianmeal moth is commonly referred to as a stored product pest. This pest is in the insect order Lepidoptera. Like most other stored product pests, it is the larval immature stage that causes damage to food products. Their larva is often confused with pest beetle larvae that will do similar damage to stored food products. Indianmeal moths are considered the most common pests in homes and food warehouses. It received this common name in the United States, where it was found to be a pest of meal made of “Indian corn,” or maize. The Indianmeal moth is found in stored products and food storage facilities around the world.

The adults have a medium wingspan of approximately 3/4” long. Their wings are bicolored, mostly a pale gray with the bottom two-thirds of their wings having a reddish-brown color with a coppery luster. Adults are nocturnal, able to fly and attracted to lights.

The larvae of this species are generally off-white but have been observed to be pink, brown or almost greenish depending on their food source. Mature larvae are approximately 1/2” in length and have five pairs of well-developed prolegs that help them move considerable distances. The larvae are the ones that are responsible for damaging foods. They have a varied diet, which includes grain products, seeds, dried fruit, dog food, and spices.

These larvae are considered surface feeders, and most of the damage to stored products occurs when the larvae spin massive amounts of silk that accumulate fecal pellets, cast skins, and eggshells in food products. The damage to stored products due to this contamination exceeds the amount of food eaten by the insects. Homeowners and managers of food processing plants, warehouses and granaries should be alert for signs of infestation.

There are many methods of control for these pests. They can be monitored using pheromone sticky traps. However, elimination and exclusion are the key elements for controlling populations of this moth. Infested food should be discarded, and any susceptible food should be placed into air-tight containers. Any spilled products should always be well cleaned in order to prevent infestations. And most importantly, old food product needs to be used first. The older the product, the more susceptible it becomes to an infestation of not only these pests, but also many other stored product pests. Be alert and on the lookout for these critters so that they don’t start residing in your pantry!