How Does a Pantry Moth Infestation Happen?

Pantry moths, also called flour or meal moths, are nuisance pests that usually appear in summer or fall in cabinets and kitchens. These tiny creatures are but the final stage of an infestation of the Indianmeal Moth, an insect that lays its eggs in grains and fruits. Sometimes mistaken for clothing moths, these moths are smaller with a wingspan of one-half to three-quarters inch. Their brown-edged wings are light gray to yellowish color and they fly in short, zig-zag patterns. The damage, unfortunately, has been done by the time these adults are noticed. The pantry moth makes its living, as its name implies, on the food that you keep in your kitchen.

Indianmeal Moths lay their eggs in any grain or fruit. This can include flour, cornmeal or cereals that you buy at the store. Dried fruit and pet food also provide attractive breeding ground for these pests. Warehouses and storage areas are constantly battling infestations of larvae in bulk shipments. Inevitably, a few larvae will get through the milling process and into the finished products. Each female moth lays from 60 to 300 eggs that hatch within a few days and spread through the food to feed for from 2 to 41 weeks. The length of the larval stage, the time when the pantry moth does its best to eat everything around it, makes its eradication difficult. The moth eggs laid in winter can wait until spring to hatch and the larvae's metabolisms slow in cooler weather, making that stage longer. At any given time in a warehouse, there may be millions of eggs and larvae at various stages of the life cycle although no moths are present. Given the pantry moth's persistence, it's easy for them to get into your flour bin. Most pantry moths are brought home from the store in these products. Animal feed and bird seed are especially likely to be infested since they are more often stored in open containers before packaging.

Indianmeal Moth larvae are resourceful creatures. They may find themselves in a bag of flour or a box of cat food upon awakening but they are able to move around quite easily, especially in open storage. When it comes time to pupate, or turn into moths, they find a warm place like the space between a pantry shelf and the wall or behind a refrigerator to gestate. Anything---spilled flour from baking to bread crumbs from the toaster---gives them a path to follow. Once they've found a place, they spin their cocoon, emerge, mate, lay eggs and die. In their short lives, they've colonized every grain-containing foodstuff in your kitchen and you're left either pitching everything or freezing it for two days and sifting out the "silk" trails. The survivors in the back of the cabinet or under the kick plate are patient---they'll wait until you've left something in a bag or box instead of putting it in a glass or metal container.

Resources

• Indianmeal Moth fact sheet
• Parents' co-op ideas