Carpenter bees are species in the genus Xylocopa that include some 500 bees and are found on every continent except Antarctica. They resemble bumble bees as they are similar in size, i.e. 12-25 mm long, but they are not bumble bees. They are mainly black in colour but can range from greenish black to blueish black or purple in colour, with white or yellow markings on the top of their bodies.

The name carpenter bee is derived from their nesting habits, as they frequently burrow into wood. These burrows or tunnels are nests used to raise their young ones and are constructed into separate compartments for each bee larvae.  

In residential and built up areas they tend to make their burrows into the overhanging roof rafters. The raising of young is seasonal and therefore the bees will return annually, and in many cases more than one return, which leads to the expansion of their burrows. Over many years the damage can become extensive and can lead to structural failure.

Carpenter bees do not ingest or eat the wood, so they are not your typical wood destroying insects like wood borers or termites that attack wood as a source of food. Since wood is not a source of food, they will sometimes even burrow into pressure treated wood e.g. CCA treated timber or poles. One often hears that applying creosote or carbolineum on the surface of the wood helps to keep the bees away, but there are also many reports to the contrary.

To effectively control carpenter bees, you have two options. Option one requires the use of a contact insecticide that can be applied by spray directly to the bees as they move in and out of their nests. This however only deals with the ones that are sprayed. Insecticide sprayed into the hole will evaporate and not be effective on the young ones who are snugly protected within their separate closed off compartments. To effectively deal with them one must apply a generous amount of gel-based poison into the burrow. A homemade mixture of petroleum jelly and insecticide can also be made. After applying the gel-based poison the hole must be closed with a dowel. This will ensure that any adult bee coming into contact with the gel will die, and when the young are ready to leave the nest, they too will have get past the gel, and will die trying to eat through the dowel.

Option two does not require any insecticide but entails the use of a “carpenter bee trap” which allows the bee to enter but they cannot leave, and subsequently starve.  The trap is simply a square box made of wood, e.g. SA Pine, with 12 mm holes drilled on the sides. The holes are drilled at a slight upward angle so that rainwater is kept out, like the method used by the bees make when making the entrance to their own burrows. An empty container e.g. plastic water bottle is attached to the bottom of the trap so that it can easily be removed to empty the bottle from any captured and dead bees.  

SAWPA can be contacted at 011 974 1061 or admin@sawpa.co.za, or visit our website at www.sawpa.co.za.