Stored-food pests

Return to Home Insect Control articles.

Imagine making a fresh cherry pie. Think about the light flakey crust, the sweet juicy cherries, the saw-toothed grain beetles, the … wait, WHAT? Yes, the saw-toothed grain beetles. Those are the little reddish-brown beetles that get into your flour every now and then. Let’s first talk about getting rid of the beetles, and then we’ll get back to the cherry pie.

How stored-food pests get inside your house
No matter how hard you try, or how clean you keep your house, I’m guessing you’ve had a bout with stored-food pests. They naturally occur outside. They hitch a ride inside on the grocery bags and boxes, and the longer we leave their favorite foods sitting on the shelves, the better the odds are that you’ll eventually see some of them. Stored-food pests usually like grains such as pastas, rice, cereals, flour and even spices. They are also fond of birdseed and pet food. And they especially like bulk-size paper bags and boxes that are easy to get into and hide in the food closet for six months.

Identifying stored-food pests
There are probably a half dozen stored-food pests you should know about. The saw-toothed grain beetle is one of my favorites. It is named for the peculiar structure of the prothorax (section between head and wing covers), which bears six saw-like tooth projections on each side. This makes it easy to identify even though it’s only about 1⁄10” long. A couple other beetles you could see include the confused and red flour beetle, cigarette beetle, drugstore beetle, and cabinet or carpet beetle.

A slightly different pest you could see would be the Indian meal moth. The Indian meal moth is rather handsome, with nearly a 3⁄4-inch wing expanse. It is easily distinguished from other pantry pests by the peculiar marking of its forewings — reddish-brown with a coppery luster on the outer two-thirds and whitish gray on the inner or body portion. This is the tiny moth frequently seen flying around lights in your home. Of all these pests, it’s the small worm-like larvae that actually do most of the damage to our stored foods.

Controlling stored-food pests
Controlling stored-food pests starts by trying to determine the source of the infestation. If you look long enough, you should eventually find a food source that is crawling with adults and larva of various stages. Getting rid of this source by throwing it out is the first step, followed by a good cleaning of all the other pantry shelves. Remove all the food items, vacuum shelves and crevices to get rid of food particles and insects, and then wash down surfaces with soap and water. If you want to take an extra step, you can treat shelves and walls with a ready-to-use insecticide labeled for indoor use. Once the surface has dried to the touch, perhaps overnight, you can return the food items to the shelf.

Other options for control include using traps and insect growth regulators. The traps have non-toxic sticky glue and use pheromone lures to attract the pantry pests. Pheromones are natural compounds that are created in the body of an insect and are used to communicate with each other. Insect growth regulators (IGRs) are unique by preventing pest larvae either from progressing to the adult stage, causing sterility of adults or preventing the emergence of insects from the pupal stage, preventing future infestations. Stored-food pests encounter insect growth regulators the same way they encounter insecticides — contacting a treated surface. A couple of IGRs include Gentrol and Archer.

Remember that controlling stored-food pests is a combination of good sanitation, eliminating the contaminated food and treatment. Better yet, try preventing the outbreak by storing all foods in plastic or metal airtight containers and bulk items in cold storage until you need them.

Now, back to that pie. Once you are sure all the saw-toothed grain beetles are gone, my favorite pie is cherry. And, I don’t even mind canned pie filling.

Other Resources

• Common Stored-food Pests
• Controlling Stored-food Insects

Contact Us

Juju Wellemeyer
Natural Resources and Mid/Small Scale Agriculture Agent juju.Wellemeyer@jocogov.org