Harry Williams, Professor Emeritus, and Jaimes Yanes, Jr., former Assistant Professor Entomology and Plant Pathology

The name "carpenter bee" is applied to several species of bees found in the United States. The only one of importance in Tennessee is a large species, Xylocopa virginica (Linnaeus), which is widely recognized as the carpenter bee (Figure 1). It resembles a bumble bee as it is robust, about one inch in length and black with some markings of yellow hair. Unlike that of the bumble bee, the top surface of the carpenter bee's abdomen lacks the yellow hair markings. It is almost devoid of hair and appears to be entirely black.

Habits

Carpenter bees are, generally speaking, beneficial insects because they pollinate numerous species of plants. They may become destructive, however, through their habit of excavating galleries in structural timbers, which weakens the timbers. Carpenter bees often fly erratically near eaves and gables of houses. Residents may become frightened by this activity because male bees patrol these areas and may fly about the faces of people.

They are unable to sting. The females do not actively defend the nest, but will sting if handled.

People may become more alarmed when holes, about one-half inch in diameter, begin to appear in exposed wood. In addition, unsightly defecation stains are usually present near these holes.

The circular gallery entrance hole is a nearly perfect circle. It usually goes straight into the wood a short distance, makes a 90-degree turn and runs with the grain of the wood. Several galleries may lead from a single entrance hole.

The female constructs individual brood cells in the gallery, provisioning each with pollen and nectar before laying an egg and sealing the cell. The resulting new bees emerge in late summer, feed for some time and then re-enter the galleries to pass the winter. The next spring, they re-use the existing galleries or construct new ones. Such an infestation may persist for several years.

Carpenter bees attack many species of dried, seasoned wood but seem to prefer softwoods such as pine, fir, redwood and cedar. They may damage porch and shed ceilings, railings, overhead trim, wooden porch furniture, dead tree limbs, fence posts, wooden shingles, wooden siding, window sills and wooden doors. They prefer unpainted or well-weathered wood to painted or hardwood timbers.

Control

Carpenter bees can be controlled by placing a spray or dust formulation of an insecticide into the galleries. You can use insecticide-soaked cotton to plug the holes. Treat after dark when bees are calm, preferably on cool nights. You can get pressurized cans of spray that shoot a stream of spray for quick knock-down of bees. The spray is good for just that purpose, but does not normally reach into the galleries.

The spray may be used to immobilize the bees while you otherwise treat the nest. After treatment, fill the holes with plastic wood, caulk or a wooden dowel glued in place.

Use a 5 percent carbaryl (Sevin) dust or a residual spray with 1 percent carbaryl (Sevin), 0.5 percent chlorpyrifos (Dursban) or 1 percent propoxur (Baygon). You can also use pyrethrins, resmethrin and dichlorvos (DDVP, Vapona), but they have no residual effect to help prevent reinfestation.

Treat existing or likely nesting sites in the spring. Make one application of one of the above residual sprays when the bees first become active.

PRECAUTIONARY STATEMENT

In order to protect people and the environment, pesticides should be used safely. This is everyone's responsibility, especially the user. Read and follow label directions carefully before you buy, mix, apply, store or dispose of a pesticide. According to laws regulating pesticides, they must be used only as directed by tbe label.

Pesticides recommended in this publication were registered for the prescribed uses when printed. Pesticide registrations are continuously being reviewed. Should registration of a recommended pesticide be cancelled, it would no longer be recommended by the University of Tennessee. Use of trade or brand names in this publication is for clarity and information; it does not imply approval of the product to the exclusion of others which may be of similar, suitable composition, nor does it guarantee or warrant the standard of the product.