How can there possibly be beetles in an unopened box of cake mix? I just bought it last week and when I opened the box this morning, there were little dark beetles inside! Doesn’t that mean the cake mix manufacturer is responsible?

M.M., Woburn, MA

Maybe yes, maybe no. Unfortunately, it is very difficult to pin down the source of a food insect infestation. Food can become infested at several stages from harvesting through storage, through packaging and shipping, and even while sitting on store shelves (see How Do Food Pests Get Into My Food?).

People think that once a food item is boxed, bagged, or sealed, that it is safe from infestation. Modern food packaging is no barrier to most insects that infest foods. The only types of manufactured food packages that are exempt from insect infestation are canned or bottled goods. The most susceptible packages are paper or cellophane bags, and any unlined packages that allow food odors to escape.

Some food-infesting insects with strong jaws actually chew their way into the package. They need an edge to get started, so the more edges or folds on a food package, the more susceptible it is to penetration by insects like rice weevils, grain borers, and rice moths. Other insects that can’t chew their way in are flattened in shape, such as the sawtoothed grain beetle, so they can squeeze their way inside. These insects can enter through sealed seams or even through stitching holes.

Food Infestations Can Start at Home

If you had purchased that cake mix quite some time ago, I would say it’s even possible that the infestation came from your own home. Once there is an infestation of food beetles or moths, they can easily spread to other food packages, even sealed packages. In addition, many food insects also feed on other items around a home. The same beetles that you found in the cake mix might have been feeding on pet food in the garage, a dead mouse in a wall void, or lint that has accumulated under the sofa (see Pantry Pests Outside of the Pantry).

You usually can’t tell whether or not a package is infested until you open it. Then you may find small beetles or moths on the surface of the food. In the early stages of an infestation, there may be only eggs or tiny larvae in the product which can be impossible to see. Pour out the product and look for the larvae feeding near the bottom of the package. You may find the shed skins of beetle larvae or webbing left by moth larvae. There may be an “off” odor to the food. See How to Check Food Products for Insects – Advice From the Pros.

Be Diligent When Buying Packaged Foods

When shopping, avoid any food package that looks damaged: dented, smashed corners, cellophane seal torn, unglued flaps, torn stitching, etc., or that has tiny holes in the surface. Often boxes that have been nicked by a box cutter will look perfectly normal at first glance. Always check the “sell by” date because older products are more likely to be infested. Rotate products on your shelves, use the oldest first, and don’t store any foods past their expiration date.

If you end up with a food insect infestation in your kitchen or pantry, give Colonial a call. Our trained technicians can stop that infestation before other food items are infested.