I often get questions at this time of year about bumblebees making holes in the woodwork at homes, shops and sometimes even furniture. Truth is, the insects making those holes are not bumblebees — they’re carpenter bees.

Carpenter bees are often mistaken for bumblebees. They, however, do not belong to the same entomological family, so their biology and habits differ. One of the most easily observed physical differences is that the top of the abdomen of a carpenter bee is slick and shiny, while a bumblebee’s is covered with black, white and yellow hairs.

John C. Coccaro is county Extension director. Write to him at 1100-C Grove St., Vicksburg, MS 39180 or call 601-636-5442. E-mail him at jcoccaro@ext.msstate.edu.

For those of you who are into scientific names, Xylocopa virginica is the primary species of carpenter bee found in Mississippi. Male carpenter bees — the ones with the white face — are hard to miss, especially when they hover in your face. These males are harmless, as they have no sting.

The females, on the other hand, do have a sting but will generally not bite unless forced. They are not aggressive. Unlike the males, who have the white dot in the middle of their faces, the females have a solid black face. The females also don’t have time to buzz about and entertain us with aerial acrobatics. They are too busy boring nesting galleries, laying eggs and collecting pollen to take back to the gallery.

The galleries the females make are about 1/2 inch in diameter and might grow up to 2 feet long. They prefer making the galleries in soft, unpainted lumber such as pine, cypress or cedar. Some find it interesting that the females will reuse and enlarge old galleries from year to year, which weakens timbers over time. The galleries also allow moisture to enter the wood, which speeds decay. 

Sealed or painted wood is seldom attacked by carpenter bees. However, it is sometimes impractical to paint exposed beams and rafters in barns or storage sheds, for example. Also, the unpainted, unfinished, rustic-looking wood is preferred by many homeowners.

If you paint, it is important for the paint or sealant to be thick enough to cover the wood grain. Otherwise, the bees will bore through the paint as long as they can still feel the wood grain.

The most effective way to control carpenter bees with insecticides is to apply small amounts of insecticide dust directly into the galleries. Female bees are killed when they return to the gallery, and newly hatched bees are killed when they emerge. Dusts work better than liquid or aerosol because they remain in the gallery, where they will contact the bees rather than soak into the wood. Ask for an insecticide dust containing deltamethrin. There are several labeled for bee and wasp control.