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Growing Green: Return of the Pantry Invaders

I fear the cold weather has come to stay (was there ever an “Indian Summer” this year?), and hopefully you have completed most of your fall garden chores.  Now is the time to sit back, relax, and ponder the successes and failures of this season’s garden, what you will do differently and what new additions will be included in next year’s garden. This is also the season that I have time to clean and inventory my kitchen shelves and make plans for holiday baking. After last year’s oatmeal fiasco, I am keeping a keen eye out for kitchen invaders. This leads to this week’s favorite BUG question: How do I get rid of grain moths? Let’s revisit some suggestions for identifying and managing them in your kitchen.

Although there are many different types of pantry pests, the most common is the Indian Meal Moth.  The adult moths are about ½ inch long with a brown band across the wingspan. The juvenile “worm” is also about ½ inch long and white. The larvae feed on grain products, including: flour, cake mix, cornmeal, rice, spaghetti, crackers, cookies, seeds (such as dried beans and popcorn), nuts, chocolate, dried fruits, spices, powdered milk, dry pet food, birdseed, ornamental corn and dried arrangements, some garden seeds and potpourri. (I’ve even found them in my baking soda!!)  If you open a container to find silk webbing around the surface of the food, chances are you have grain moth larvae.  (You might also find beetles and weevils.)

So, what should you do if you have these pantry pests? Locate the source of the infestation; check all grain based foods for signs of insects. Throw out the infested food products. (If you have a large amount of grain that you absolutely don’t want to throw out, try heating the product to 130 degrees for 30 minutes, or freezing it for 3-4 days.  This will kill all insects.)  Empty your pantry and thoroughly clean your cabinets and shelves with a vacuum cleaner to pick up any spilled or infested material in the cracks and corners. Washing shelves with detergent, ammonia or bleach will not prevent re-infestation. There is also no evidence that bay leaves or spearmint gum placed in the cupboard will prevent grain moths. As a precaution against re-infestation, consider storing susceptible foods in clear glass, metal or heavy plastic containers. (I have had moths infest grains stored in plastic storage bags and inexpensive plastic storage containers.  Glass canning jars with screw top lids tend to keep the bugs out.) It is common to find adult moths flying for as long as three weeks after the source of caterpillars have been eliminated. So long as the food sources have been adequately stored, re-infestation shouldn’t be a problem.

Don’t use insecticidal sprays in food storage cupboards. They are ineffective against insects within food storage containers, and could pose a health threat to humans if used improperly.

Robin Trott is a Horticulture Educator with University of Minnesota Extension.