Are Carpenter Bees Damaging Your House?

With the warm weather of spring arriving, we have a familiar visitor, the carpenter bee. These large bees are by far the most active during the spring time, looking to put new holes in decks, house eaves, and any exposed wood they can find. They look very similar to the bumble bee, but the upper surface of their abdomen is shiny and black, whereas, the abdomen of the bumble bee is hairy and has some yellow color on it. A good thing about the carpenter bee is, the male, which is the one you see hovering threateningly, does not have a stinger and cannot harm you. The female can sting but only if she is handled or stepped on. The adult bees will come out of old, abandoned nest tunnels in the spring and mate. The females then bore tunnels in wood structures and lay their eggs. The eggs are laid in a series of cells that are capped off with a ball of pollen. This is food for the larvae after they hatch. The larvae will emerge from the tunnel nests in late summer as adults.

 
The carpenter bee tunnels are bored holes about the size of your little finger. They are bored into homes, barns, and other wooden structures, especially those that have bare wood or unpainted surfaces. The type of wood is usually a softwood such as cedar, cypress or pine. The holes are found along the eaves, window trim, and in the siding of these structures and even in outdoor furniture. Usually, painted or pressure treated wood will prevent them from boring holes.

 
The effectiveness of the carpenter bee is questionable when it comes to being a crop or fruit flower pollinator. They are effective in pollinating the passionfruit, and they visit blooms of blackberry, canola, corn, pepper, and pole beans. But, they are known for cutting slits in the side of the flower to rob the nectar without even touching the pollinating parts. Blueberry growers have to be especially concerned because the carpenter bees will make these robbery holes and cause other bees to be attracted to them instead of pollinating the flower.

 
Controlling the carpenter bee requires the use of a chemical insecticide. A liquid spray of Sevin, Spectracide, permethrin, or deltamethrin sprayed into the bored nesting holes about once every 14 days will help control the bee population. The insecticide needs to be sprayed into the holes so that the bees will get it on their feet. When they begin cleaning themselves, the chemical will be ingested and the bee will die from it. The holes should be plugged with wood filler and the wood surface painted in August, when all bees have left their nest sites. This will help those late summer and early fall adults from having a place to overwinter.

 
Carpenter bee traps have varying success in controlling bee populations. Most of the bees trapped are male bees, which can help the overall breeding populations of bees. Traps can be bought at a variety of stores or there are several plans for building your own found online. For best results with traps, they should be placed on the sunny side of the structure to provide a warm and attractive environment for the bees. We are always here to help at the Banks County Extension office. Call, email, or stop by our office today for more information.