Indian meal moths a fine diet of fun for cats
December 9, 2001

The two pet house cats have been amusing themselves chasing and batting down numerous tiny tan moths that have invaded the house, especially the kitchen area. What are they? Where did they come from? How does one get rid of them? A Woodland Dunes naturalist's library to the rescue.

These are Indian Meal Moths, a major pest of stored grains, grain products and dried vegetable products, anything from soup (if dehydrated) to nuts. All stages of the life cycle may be found indoors all year. Scientific name Plodia interpunctella, which does not really describe this tiny brown moth. However, it is distinctively marked. The base of its wings is silvery white with coppery sheen which blends well with most kitchens.

May R. Barenbaum in her book entitled "Ninety-nine Gnats, Nits and Nibblers" has devoted an interesting chapter to these little pests.

The Indian Meal Moth does not materialize out of thin air. It spends its formative weeks in any kind of dried food. The larval stage takes about eight weeks. The mature larva are generally whitish with a green or pinkish hue. Their presence may first be noted by the silken threads they spin as they feed. In commercial flour operations they can cause tremendous problems by clogging machinery with their webbing. In a home they can cause housewives to go into a conniption. When they are ready to pupate they tunnel through whatever they are feeding on and come to the surface, then they are likely to cake the flour, leaving mold and excrement in their wake. At this time in their search for a place to pupate they may often engage in the unsettling practice of walking along kitchen cupboards or walls and ceilings.

In granaries and flour mills, the Indian Meal Moth may cause considerable damage by eating the seed germ. They foul the meal by encouraging the growth of mold and fungi. Spoilage limits the growth of these pests as the grain begins to rots it heats up due to fermentation. This makes the flour unsuitable for moths and humans alike.

About the only practical control at home is to toss out the contaminated material. If you choose not to waste the food it can be frozen for several days, but one runs the risk of insect parts in cakes and cookies.

The U.S. government has standards for the number of insect parts in various processed food stuffs. A quick estimate puts about 56 insect parts in a peanut butter and jelly sandwich.

Unopened boxes should be stored in the freezer. Check open boxes, frequently. At the first sign of moths, dump the whole works. Buy bird seed in small quantities such as the gallon jugs available at Woodland Dunes. Use the bird food up quickly as this type of wild bird food is a common source of Indian meal moths.