Pantry Pests

Indian meal moth is one of the most common stored product insect pests. The adults are small but distinctive 1/2-inch long moths. Two-thirds of the front pair of wings is reddish-brown while the remaining third is light gray (Figure 1). Hind wings are gray with no distinctive markings. The moths are attracted to light and may fly to rooms far from the infestation source.

The larval stage, a caterpillar (Figure 2), is cream to pink and about 1/2 inch long. They may be found crawling up walls or across ceilings. These full-grown larvae wander away from their food source and find a spot to spin a cocoon and pupate.

Figure 1. The distinctive two-tone color pattern of Indian meal moth front wings makes them easy to recognize. (Photo: MJ Raupp, University of Maryland)

Figure 2. Larval stage of the Indian meal moth (Photo: Lee Townsend, UK).

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Indian meal moth larvae feed on a wide variety of processed foods from meal, to cereal, to powdered milk. They can also be found in dried fruits and peppers, stored seed, bird feed, and nuts. The surface of infested items becomes covered with a layer of silk. Larvae feed for 2 to 3 weeks; the life cycle from egg to adult takes about 6 to 8 weeks.lank

Management

The key to eliminating Indian meal moths is thorough sanitation: find and destroy their breeding sites. If the infestation has been active for several months, the insects may be developing in a variety of sources. Start with pantries and inspect all processed foods, especially flour, meal, mixes, and dried pet food.  Pay particular attention to partially used bags that have been sitting around for some time. It is best to discard any infested materials. Then, use a strong suction vacuum cleaner with crevice attachment to clean shelves and in cracks and crevices. If shelving is removable, clean all surfaces, including backs, where moth cocoons or small amounts of food can be overlooked. Mature larvae may travel some distance from the infested material to pupate, so moths may be seen several weeks after a cleanup.

Spraying to kill moths or wandering caterpillars will not solve the problem.  Moths and caterpillars are most common in spring and fall, but they can be found throughout the year. The moths do not feed, but they can find and infest other items.

Prevention

Check packaging dates when buying products, and do not buy products in damaged packages. Purchase seldom used meals and mixes, as well as small grains, in small amounts and store in sealed containers so emerging adults cannot move to infest other materials.. Store susceptible products in a refrigerator or freezer. Mark the purchase date on packages so the oldest ones can be used first. Store foods in airtight glass, metal, or plastic containers. Clear containers make it easier to check for infestations.

 

By Lee Townsend, Extension Entomologist

 

 

Posted in Household Pests