The unusual sight of a cream- to pink-colored caterpillar (or two) leisurely crawling up a kitchen wall or across the ceiling raises the distinct possibility of an Indian meal moth infestation.
The Indian meal moth is one of the most common stored product insect pests in Kentucky. The adults are small but distinctive ½-inch long moths (Figure 1). Two-thirds of the front pair of wings is reddish-brown while one-third is light gray. 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, is cream to pink and about ½ inch long (Figure 2). They may be found crawling up walls or across ceilings. Full-grown larvae wander away from their food source and find a spot to spin a cocoon and pupate.
Indian meal moth larvae feed on a wide variety of processed foods, including meal,cereal, and powdered milk. They can also be found in dried fruits and peppers, stored seed, bird feed, dry pet food, 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.
Locate and destroy breeding sites
Eliminating an infestation of Indian meal moths, or any other stored product pest, requires finding and destroying all infested items. Spraying to kill moths or wandering caterpillars will not solve the problem. Usually, an infestation has been active for several weeks before wandering caterpillars or flying moths become apparent. By that time the insects may have spread beyond the initial infested item. Give top priority to processed materials, especially flour, meal, mixes, and dried pet food. Begin with those that are only used occasionally and stored in paper or cardboard containers. Insects are most likely to be able enter and leave these types of containers. Look for caterpillars and webbing of the fine silk that they produce. Seal infested commodities in bags and discard them immediately.
Clean the storage area thoroughly after infested items are removed. Small amounts of food can contribute to chronic infestations or attract new ones.
- Watch for silk cocoons of developing moths under cans or packages and remove them.
- Use a vacuum cleaner crevice tool or wipe up small amounts of meal, flour, etc. that have accumulated in cracks and crevices and under stored items.
Infestations are most likely to occur in packaged items that have been around for some time.
- Check packaging/expiration dates to avoid buying old items. Mark the purchase date on packages so the oldest can be used first.
- Do not buy products in damaged packages.
- Purchase whole grains and any seldom-used meals and mixes in small amounts, when practical.
- Store foods in airtight glass, metal, or plastic containers so emerging adults cannot move to infest other materials. Clear containers make it easier to check for infestations.
- When possible, store susceptible products in sealed containers in a refrigerator or freezer.
By Lee Townsend, Extension Entomologist