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Pantry Pests

Posted: November 22, 2011

On occasion, you may find tiny bugs flying or crawling on a windowsill, or small moths fluttering about the house, even in the middle of winter. Where could these insects be coming from?
Indian Meal Moth

Indian Meal Moth

There are a number of insects, collectively known as “pantry pests” or “stored product pests”, that can infest stored food products or dried plant material in your home. A few may go unnoticed, but these insects can quickly become an abundant and annoying nuisance. Fortunately, though, in general they do not bite or sting humans or spread disease. The only reliable method of control is to find and get rid of the source of the infestation, followed by a thorough cleanup and proper storage to prevent re-infestation.

Most common pantry pests are either beetles or moths, with four stages of development: egg, larva, pupa, and adult. The egg is so tiny that it is rarely seen. Although it is the adult stage, beetle or moth, that is most often seen, it is the larval stage, caterpillar or worm-like “grub,” that generally causes the most damage in the infested material. The larva consumes the food directly, but the food is also contaminated by eggs, shed larval skins, fecal material, or other insect matter so that it develops “off” colors, odors, and flavors. Infested foods should be discarded.

The most common pantry pest insect is the Indian meal moth. They are sometimes mistaken for “clothes moths,” but they have some distinctive identifying features. Small, about ½ inch length, with fore wings that are half copper-colored and half whitish-gray, they tend to flutter about lights at night, often in the kitchen or pantry, or hang on the walls. The larvae are caterpillars, dirty white to pinkish in color, that produce silk webbing as they crawl and feed on the infested material.

Other common pantry pests include Angoumois grain moths, cigarette and drugstore beetles, confused and red flour beetles, sawtoothed grain beetles, carpet and cabinet beetles, seed weevils, and granary and rice weevils. Although these beetles vary in shape, size, color, and biology, in general they are all small, hard-shelled, reddish-brown to black insects ranging in length from 1/16 to ¼ inch.  Some can fly, some only crawl, some are attracted to light, so they may be found in a different part of the house than the source of infestation.

Insect pantry pests can infest a wide variety of stored food products, including flour, bran, meal, cereals, pasta, rice, boxed cake mixes, crackers, chocolate, seeds, nuts, dried fruit, grains, spices such as pepper and paprika, herbs, corn starch, powdered milk, dry pet foods, bird seed, and various drugs. Drugstore beetles have even been known to feed on strychnine without harm. Some may infest decorative materials such as dried flower arrangements and Indian corn. The longer an item is stored in one place, the more likely it is that it may become infested.

Because these insects can infest such a wide range of materials, it may be difficult to pinpoint the source of the infestation. But you must find and discard the infested material, followed by a thorough cleaning of cupboards and shelves, including cracks and crevices, to control the problem. Even a tiny bit of food debris left in the space between shelf and wall may be enough to sustain a population.  Insecticide sprays should not be used near food; but they are of little use anyway if the infested food remains in the house. Food products should be stored in air-tight glass, metal or heavy plastic containers to prevent re-infestation. Store dry pet food and bird seed in closed containers outside.