Question

I have an old cutting board that belonged to my grandmother that I keep in my kitchen just as decoration. I recently noticed some small holes on one edge of the cutting board and a little bit of sawdust below. I put the board in a plastic bag and some tiny insects emerged. An entomologist identified them as drugstore beetles which, from everything I can find, feed on stored foods, not wood. What were they doing in the cutting board?

Answer

That’s just one of those things that makes entomology so interesting. Drugstore beetles are indeed primarily food pests, feeding on anything from cereal to dry pet food to spices (also drugs-that’s how they got their name). They’re absolutely not interested in feeding on wood but they are interested in tunneling into wood to make a nice, protected place to pupate. That’s where the cutting board comes in.

Drugstore beetles are actually closely related to wood-infesting powderpost beetles. Like their wood-infesting cousins, the larvae also have strong jaws which allow them to chew into packaging…or tunnel into wood. Usually this wood damage occurs to kitchen cabinets since that is where you are most likely to find the beetle larvae feeding in boxes and bags on the shelves.

There are a number of beetles that infest foods that will sometimes tunnel into wood if the opportunity presents itself—it’s sort of a random thing. Once the larvae have gorged themselves on the foods in your pantry, they go into a pupal or resting stage before turning into adult beetles. Some beetles will pupate right in the food material where they have been feeding. Others wander away from the food, often pupating in cracks and crevices nearby. If they’re not finding a suitable spot and there’s some nice soft, old wood nearby—why not!

While this phenomenon is uncommon in homes, it’s a serious problem in chicken houses. Chicken houses are often infested with larder or hide beetles that feed on chicken feed, feathers, dead birds, and droppings. Occasionally a chicken house, granary, mill, or packing plant will suffer major structural damage when thousands of food beetle larvae bore into wooden beams to pupate!

Now you know why the beetles were in the cutting board, but I’m assuming your next question would be, “where did they come from?” It’s almost certain that somewhere in your kitchen or pantry, you have some beetle-infested foods. Finding the infested food often means going through everything that is not packaged in a jar or can, looking for tiny, white larvae in the food. A pest control company can help you with your search and can treat cabinets to eliminate any beetles that found their way into cracks instead.

Here’s a free hint though: these “pantry pests” are usually found in foods that are older (past their “use by” date) or that are damp or moldy or otherwise in poor shape. In most homes, these are the boxes and bags that have been shoved way to the back of the shelf and forgotten! For example, I was recently putting down new shelf paper on the very top, corner shelf in my kitchen; you know, the shelf that is not very accessible. For that reason, it’s the shelf where I keep baking items for the baking that I almost never do. Way in the back, I found a package of chopped nuts that expired in 2004! That would have been prime food for these pests.