This is a unique question because there isn't really a straightforward answer. When a porch sinks down at one corner, a balcony collapses, a shed leaks, exterior stairs break, or some other outside wood structures begin to show the effects of carpenter bee damage, the question of how much damage does a single carpenter bee cause becomes a philosophical one. Consider this quote from journalist Jacob Riis:
"When nothing seems to help, I go and look at a stonecutter hammering away at his rock perhaps a hundred times without as much as a crack showing in it. Yet at the hundred and first blow it will split in two, and I know it was not that blow that did it, but all that had gone before."
These are some pretty wise words. And, while we can certainly draw from this quote a lesson about how the things we do have an impact on our world, it also gives us some insight into the insect known as the carpenter bee. It isn't one carpenter bee that causes your deck to collapse. Nor is it, necessarily, the work of a hundred carpenter bees. It is the constant assault, year after year. And, like Jacob Riis, you can know that it wasn't the first carpenter bee that did it but all the carpenter bees that had gone before.
As you probably know, carpenter bees bore circular tunnels into wood. What you may not know is that a single carpenter bee is only going to make a tunnel that is about 1 foot long. They usually start by flying upward and clinging to a piece of wood. Then they tunnel into the wood. A short way in, they make a turn and go along the grain of the board. Most of the time this is a 90% turn. As they make these tunnels, they cause the wood to weaken. This weakness spreads to other boards and the frame of the entire structure can begin to warp. When it does, walls can bulge, floors can sink, and ceilings can dip.
Most of the time, carpenter bee damage does get to this point. Unlike termites, which live almost exclusively inside the wood they are consuming, carpenter bees have no trouble being exposed to the air or the sunshine. For this reason, you are likely to see holes forming in wood that carpenter bees are boring into. This happens when the tunneling bee gets too close to the exterior of the wood. One place this is often seen is on rooflines and eaves. And, while not necessarily a hazard, it is definitely unsightly.
Carpenter bees prefer untreated wood. If you have untreated wooden items in your yard, like a fence, a shed, a deck, or something similar, carpenter bees will be able to do more damage more quickly. Painting, staining, or treating these items is a good way to resist carpenter bees.
The best way to control carpenter bees is with the help of a professional pest control company. DIY methods can cause female bees (the ones that do the damage) to become trapped. If trapped, they will bore a new tunnel to escape. And new tunnels mean more damage.
Getting rid of carpenter bees also requires the use of insecticides. When these products are not administered in a proper manner they can be toxic to pets, children, and adults living in the structure being treated.
If you are seeing holes that you think may be caused by carpenter bees, here is a quick way to identify these insects. Carpenter bees and bumble bees look very similar. They are both big bees with black and yellow hairs, but carpenter bees have a black abdomen. Bumble bees have an abdomen adorned with yellow hairs mixed with black. This distinction can be seen from several feet away. It also helps if you actually see the bee climbing out of a hole. Bumble bees don't go into holes.
If you have carpenter bees on your property, and you're in our Pennsylvania service area, contact Witt Pest Management for an effective resolution to your problem that won't lead to more damage. A single carpenter bee isn't much of a threat. But a carpenter bee infestation that isn't treated, is a threat.