Q: I have heard that some species of wasps and bees can damage my house. Is that true?
A: Yes! The threat to our homes is not as common as with termites and carpenter ants, but we do have species of wood-destroying bees and wasps in the Northwest that, if left untreated, can do serious structural damage.
Carpenter bees can be a real nuisance to homeowners because they tunnel into decks, porches and other wood structures.
They are often mistaken for bumblebees, but bumblebees have hairy abdomens and carpenter bees’ abdomens are smooth and shiny.
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If you see what looks like a bumblebee emerging from a hole in your porch or the siding of your house, it is not a bumblebee. It’s a carpenter bee.
Carpenter bees typically spend the cold months inside their empty nest tunnels, protected from freezing temperatures.
In the spring, they emerge ready to mate. The female excavates a tunnel for her offspring. In each brood chamber, she stores food and lays an egg.
By late summer, her young emerge as adults. If you notice bees that seem to be coming from a hole in your fascia board, deck posts or other wood structures, that’s a sure sign those holes are nests.
A carpenter bee hole is approximately a half-inch in diameter — just big enough for the bees to fly in and out. Their tunnels are about six to eight inches.
Though they burrow into wood, carpenter bees don’t eat wood the way termites do. The threat of structural damage comes from the fact that because the tunnels require a lot of effort, female carpenter bees prefer to refurbish old tunnels rather than digging new ones. If carpenter bees are allowed to tunnel in the same structure year after year, the cumulative damage can be significant.
Carpenter bees are excellent pollinators and very beneficial to the environment and to our food sources, so they should only be eliminated if they have taken up unwelcome residence.
If you do have a problem, the common treatment is insecticidal dust, which is usually applied with a puffer that coats the interior surface of the entrance holes. It is most effective to apply the insecticide in the spring, just before the adults emerge to mate.
Once you see the bees emerge, wait a few days and then fill and seal the holes with wood putty. Bees are active during the day so it is preferable to apply pesticide at night or just before dawn to reduce the chances of being stung.
Several species of wood wasps and horntail wasps will also infest structures.
They typically do not infest seasoned wood, preferring to lay eggs in dying or recently felled trees. Sometimes, however, they can infest wood used in construction.
The typical life cycle averages two to three years, so it is possible for adults to emerge after a new home is built. They are less of a structural threat than carpenter bees because they will not reinfest seasoned wood.
A general-use insecticide can be used on wasps if they are a nuisance, and particularly if someone in your family is allergic to bee and wasp stings.
HomeWork is the weekly column by the Master Builders Association of King and Snohomish Counties’ Remodelers Council about home care, repair and improvements. If you have questions about home improvement, send them to homework@mbaks.com.