I have had a problem with flour beetles in my kitchen for about two years! I know they’re flour beetles because we had an exterminator out here last year. That seemed to work for a while but now I’m finding them again in the cupboards. Help!

R. B., Merrimack, NH

Any kind of stored food insect can be difficult to get rid of because so many types of foods can be infested. Flour beetles are no exception. Despite the name, flour beetles will feed on a wide range of food products – from cornmeal, flour, crackers, cake mix, to chocolate, beans, spices, and many more things in between (see Flour Beetles Aren’t Just in Flour!). Think about places other than the kitchen where foods might be stored. For instance, a bag of dry dog food or birdseed in the garage could be the primary source of your recurring infestation.

Flour Beetles Can Be Inside Sealed Packages

Flour beetles are very successful pests because they can infest food products at any stage, from raw grain to finished baked goods. For that reason, it’s hard to track the source of the infestation. Another reason that flour beetles are such problems is that they have flattened bodies, allowing them to squeeze into all but the tightest packages where the female will lay eggs. Factory-sealed boxes and bags can be infested (see Packaging is No Barrier to Food-Infesting Insects).

There are two primary flour beetles that can be found in home pantries, the red flour beetle and the confused flour beetle. They look almost identical and have basically the same habits (see Flour Beetles are Just One Type of Stored Food Pest). The whitish, worm-like flour beetle larvae avoid light and are rarely seen since they are burrowing down in the food product. The tiny, dark adult beetles (about 1/8 inch long) are usually found on the outside of the package or on top of bulk foods, or on kitchen or pantry shelves.

How to Inspect Foods for Flour Beetles

Because flour beetles can infest so many different foods, you really need to check everything on your shelves, even unopened packages. Since older, out-of-date, or damp foods are most likely to be infested, start with any that have been buried on the back of the shelves for a long time. First, sniff the contents of the package. Infested foods often have a musty smell and would have a bitter taste if you tasted them. Light-colored foods such as flour might have a pinkish-gray tint.

Because the tiny white larvae can be hard to see and are usually at the bottom of the package, the best way to check is to pour the food product out onto a cookie sheet and spread it out. For details on what to look for, see our blog, How to Check Food Products for Insects – Advice From the Pros.

Depending on what you find, consider contacting an exterminator to do a crack and crevice treatment of your shelves, pantry, and surrounding area after you have done a thorough cleaning – you don’t want to have to go through this again! Make sure you use older foods first, toss really old foods, and store foods in sealed containers or in the refrigerator whenever possible.