Picking Your Poison
If you are simply looking to kill a few carpenter bees that are posing a nuisance by hovering around the eaves of your house or porch railing, a common wasp and hornet killer effectively offers a short-term solution. These aerosol sprays, available almost everywhere, will knock carpenter bees out of the air and quickly kill them. A long-term solution to carpenter bees requires a greater investment in both time and money. Look for pesticides that contain deltamethrin, bifenthrin, permethrin, carbaryl, tetramethrin or lambda-cyhalothrin. Products containing the insecticide cypermethrin are also effective against carpenter bees. These chemicals are not always available in every state. Therefore, it is important that you first check your state's regulations regarding the use of pesticides.
Application of the Poison
The use of insecticide coinciding with plugging the carpenter bees' tunnels provides the most successful results. Initial treatment should begin in the spring, before the carpenter bees become active. Spraying the wood with the above-mentioned insecticides is effective, but only for a short period of time. The poison will have to be reapplied every few weeks to prevent the bees from drilling. One of the best methods of treating for carpenter bees involves applying a dust, again containing one of the previously noted insecticides, directly into the tunnel. This will allow the poison to come into contact with the bee and allow it to spread through the tunnels, affecting any larvae that may exist within. You can treat tunnels in the spring as well as late fall, so as to kill any bees that may be using the tunnels over the winter. After you've dusted the tunnels, plug the holes with aluminum foil or caulk. If expense is of no concern, there are carpenter bee kits on the market that provide the insecticide, a dust applicator and plugs.