If you see large black or golden-brown bees flying in your garden or landscape, don't be alarmed! These insects are most likely carpenter bees, and although their large size and loud buzzing can be intimidating, they are mostly harmless. Males can't sting and females rarely do, and both are considered beneficial because they are pollinators. 

However, sometimes carpenter bees bore into lumber or trees to make nests and may damage structural wood or leave unsightly holes and stains. Multiple bees may use a common entry hole, tunneling several feet into wood to create chambers for their offspring.

The best way to manage carpenter bees boring into wood is through prevention. Use hardwoods in structures where possible...

One of the best ways to reduce pest problems in and around buildings is to construct or retrofit structures that keep pests out in the first place. This concept has been a pillar of integrated pest management for many years. Pest-resistant buildings reduce not only pest problems but also the need for pesticide applications. Unfortunately, architects and builders had few guidelines about how to design and construct such structures.

To address this issue, the San Francisco Department of the Environment and the International Code Council developed an online publication, Pest Prevention by Design, which provides the first comprehensive resource on pest-preventive building design tactics.

Specific guidelines are...