By
Mickey Moore
Wood Flooring Advisors (WFA)
The Problem
I received a call from a member
manufacturer for a job-site
inspection. They had a complaint
about a floor that had been
installed about a year earlier. Now
the customer was noticing small
holes in some boards, and a pest
control company told her that she
had powderpost beetles in her floor.
The company recommended fumigating
her house at a cost of several
thousand dollars.
The Procedure
The floor was site-finished, No.1
common red oak strip installed over
joists. The floor had been sanded,
stained and coated with two coats of
oil modified polyurethane. At the
job site, I checked the moisture
content levels of the boards
indicated, which were 7 to 8
percent, well within the normal
range. I also measured the boards,
which were 21.4 inches wide, exactly
as they should have been. In talking
with the homeowner, I discovered
that she had not seen any actual
insects, and neither had the pest
control expert, however, he looked
at the holes and declared them to be
powderpost beetle holes. I looked
for evidence of an active
infestation. For powderpost beetles,
there are several clues. The most
obvious is spotting an actual live
beetle. Powderpost beetles have a
hard shell and measure from about
1.16 to 1.8 inch in length. When
they emerge from the flooring, their
holes are vertical to the face of
the wood. An active infestation will
have “frass,” which is the telltale
powder that accumulates around the
hole. It has the consistency of
talcum powder and looks like a
little volcano surrounding the hole.
In looking at the flooring in
question, I couldn’t find any
insects or any frass, and I also
noticed that most of the holes were
not vertical to the face of the
boards. Some finish and stain color
extended down into some holes. In
others, the entire walls of the
holes were stained, which is usually
evidence of ambrosia beetles. I
determined that this was not an
active insect infestation.
The Cause
The pest control person was correct
in that insects had made the holes
in question, however, these holes
had not been made recently. In any
case, the holes were grade
characters that existed in the rough
lumber. When the flooring is
installed and sanded, existing holes
are packed with sanding dust that is
covered by the finish. As the floor
expands and contracts, the dust
collapses, and traffic on the floor
causes the finish over the holes to
break, exposing the holes for the
first time.
How to Fix the Floor
Small holes such as those from
powderpost beetles are acceptable in
almost all grades of flooring. If
the customer objects to seeing the
holes in the floor, the typical
solution is to use a filler designed
for finished floors to fill the
holes.
In the Future
With complaints regarding potential
powderpost beetle infestations, the
most important thing is to look for
signs of an active infestation. If
it is active, it’s important to have
the bug identified by a professional
entomologist. Many pest control
workers are not qualified to make a
positive identification. If it
appears that there is an active
infestation but there aren’t any
obvious insects, one way to coax
them out is to put a glass over the
hole, wait until dark and shine a
flashlight onto the glass. The light
should attract the creatures up into
the glass so they can be captured.
If there is an active infestation of
a few boards, usually replacing
those boards will remove the bugs;
if the infestation is larger,
usually sanding and treating the
floor with a borax treatment
designed for powderpost beetle
infestations will do the trick
By
Mickey Moore
Wood Flooring Advisors (WFA)
