I am building an exterior post and beam pavilion in Kentucky and the owner is concerned about carpenter bees. We typically use douglas-fir but someone mentioned oak might be less interesting to the bees. Do you have any experience between various species for exterior timber framing?
In fact I’ve been amazed at the wide range of wood carpenter bees will utilize. No doubt they seem to prefer anything soft with pine being a favorite. So if you wish to deter them, go with a hardwood if possible. Hickory, walnut, cherry and oak are all good choices. And though redwood, cedar and douglas fir are supposed to be naturally repellent to bees, I can’t say I’ve seen this to hold up to be true in the real world. Of course we deal with people that have problems so that means we’ll get called because there is most definitely a bee problem. And when we do take notice, there are some common things we’ve learned over the years when it comes to the species of wood they like to target.
First, it’s obvious that the local supply of wood and good nest sites will have a big impact on whether they choose what you build or some place else to nest. So if there is an abundant supply of cellulose around the location where the pavilion will be built, there is a good chance something else will be targeted before the new wood you install. But if your posts and rafters are the only good nests sites for several acres, chances are high it will be a prime target to anything that likes to bore in wood like Powderpost Beetles, Carpenter Bees and Carpenter Ants.
Second, if the pavilion is left “natural” as in no stain or exterior finish, this will no doubt increase the odds of it becoming a target because carpenter bees seem to target naturally decaying wood over all else.
Third, if the wood is subject to a lot of moisture, mold and fungus, it will increase the odds of it becoming a nest site.
Fourth, if there is an abundant supply of bees nearby nesting in a somewhat limited amount of cellulose, the odds of them moving to your pavilion will increase.
In summary, I’ve seen them nest in virtually any kind of wood including pressure treated lumber, cedar painted with Duron Paint and even railroad ties! After witnessing all these woods being targeted, I’ve learned there is no magic species they’ll always ignore. So my suggestion is use the Oak if possible with the Douglas Fir as a second choice. But I wouldn’t stop there.
If you want to insure your project won’t become the target of anything destructive, make sure they know that spring and fall treatments with either CYPERMETHRIN or NBS REPELLENT can do a lot in the way of prevention. In my experience, treating is really the only way to insure a problem won’t develop.
Here are direct links to the information and products listed above:
Carpenter Bee Control: www.carpenterbees.com/carpenter-bee-control
Powderpost Beetles: www.powderpostbeetles.com/powderpost-beetle-control
Carpenter Ants: www.carpenterants.com/carpenter-ant-control