A.Terry Brennen of Camroden
Associates in Westmoreland, N.Y., a consultant who specializes
in mold and pest issues, responds: Wood wasps — also
known as horntails — aren't actually wasps at all, but
received their name because of their resemblance to their
stinging relatives in the Hymenoptera family (see photo).
Found throughout the United States and in other parts of the
world, the various subspecies of wood wasps are all fairly
distinctive looking; I believe your extension service has
correctly identified the insects discovered in your clients'
This is good news, because wood wasps don't sting or bite
people, and they can't cause any significant structural damage
with their chewing.
Furthermore, wood wasps do not colonize buildings. Most likely,
lumber used in the home's construction harbored a few larvae,
which are usually found in trees that have some damage or have
been recently felled.
A single horntail lays only a dozen or fewer eggs, inserting
them one at a time into damaged or decaying softwood. After the
eggs hatch, the larval stages of the insect might spend between
two to five years boring short tunnels in the wood.
Once they've reached the adult stage, however, wood wasps bore
an exit hole and leave, and won't recolonize these holes. So if
the insects you're finding are the result of one female, there
will be only a few. In any case, it would be un-usual to find
Because the insects aren't harmful and are likely to be small
in number, I advise against spraying or fogging. (In general, I
avoid pesticide use whenever possible.) Let nature take its
Only if you end up with more than a dozen of these harmless
insects, with no end in sight, would this mystery warrant