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Pantry pests

Published February 3, 2012

There is nothing that a cook finds more off-putting than discovering something crawling around in a box of a cooking ingredient.

"A variety of beetles and moth larvae can be found in stored food products," said University of Illinois Extension horticulture educator, Jennifer Fishburn. "These pantry pests may enter the home through infested packages of food or may fly into the house and bore through wrappers or containers." These infestations can take place at any time of the year.

Beetles and moths have four growth stages -- egg, larva, pupa and adult. The larval stage is the most destructive, although insects at all stages may be present in food. One adult beetle or moth can lay up to 300 eggs.

These pests are found primarily in food storage areas. They like cereal, oatmeal, pasta, flour, cornmeal, cake mix, crackers, powdered milk, dried fruits, dried flower arrangements, dry pet food, and birdseed.

The moth most frequently found in the home pantry is the Indian meal moth. The larvae, which are one-half inch long and white with a tinge of pink or green, prefer whole grains, cereal, dried fruits, seeds, dry pet foods, and coarse flour. Silk webbing on the foods, especially near the surface, is a sign of their presence. Adult moths are three-eighths of an inch long, with bronze wing tips and whitish gray inner wings and a three-quarter-inch wingspan. In the resting stage, they sit at an angle with their wings folded.

"The two most common beetles that infest flour are the confused flour beetle and the red flour beetle," said Fishburn. "They infest a wide variety of foods, including cracked grains, cake mixes, beans, peas, and nuts. Both beetles are reddish-brown, flattened, oval, and about three-sixteenth of an inch long. The larva is white and tinged with yellow." Other pantry pests include the drugstore beetle, the merchant grain beetle, the sawtoothed grain beetle, and the granary weevil.

Proper storage, sanitation, and regular inspections will discourage unwanted visitors. "Empty and thoroughly vacuum the shelves holding infested items; be sure to get into cracks and corners," Fishburn recommended. Remove and replace contact paper and other shelf liners. It is a good idea to wash cabinet shelves with hot soapy water, paying particular attention to cracks and crevices."

If insects are found in a package, carefully inspect all packages in the cabinet. If birdseed or pet food is stored in the home or garage, check these items for signs of insects that could migrate to food storage areas. Even sealed packages can get infestations.

Never use insecticides around food products. Discard infested foods in a heavy plastic bag or a sealed garbage can. Empty the vacuum cleaner or discard the vacuum cleaner bag after use -- some pests are capable of living for many weeks without food.

Fishburn added that you can keep pantry pests from invading your home by practicing these prevention tips:

  • Purchase only the amount of food you will use in the near future.
  • Do not purchase food in broken or damaged packages.
  • Store dried foods in airtight, insect-proof containers made of glass, metal, or heavy plastic. Infrequently used items should be stored in the refrigerator or freezer.
  • Use older packages before newer ones.
  • Keep the food storage area dry, free of moisture and clean; do not allow crumbs or food particles to accumulate in food areas.
  • Regularly inspect stored dried goods for infestations.