Pest control

Yoram Haviv <yoram [at] loop__com> writes

>Do you know of a *reliable* way to control powderpost beetle
>infestation in a small item of furniture (clocks)?

You requested alternative treatments for clocks infested in
powderpost beetles, indicating that you are a collector and your
current treatment involves the use of methyl bromide.

This is a great question since it includes a whole range of issues
which should be of interest to the preservation community. In
addition, I respect that since these are your objects you have the
absolute right to treat them as you wish.

First, I'm not exactly sure what powderpost beetle you are treating
for. My guess, based on the reinfestation of old wood, is that you
may have Lyctid beetles, Anobiid beetles, or possibly the oldhouse
borer. Knowing what you have may, or may not, change some
suggestions. I am also assuming that you are primarily concerned
with larval stages (i.e., the objects are acquired with active
frass, but that after treatment you rarely see re-infestations,
suggesting that the storage conditions after you acquire the clocks
are good and there is little re-infestation). If you are treating
and re-treating the same clocks then obviously I would suggest you
examine your storage conditions and explore options for making it
less attractive to the beetles.

Second, I'm not sure that I would use methyl bromide. There is
something around a 10% failure rate with methyl bromide when used to
control Lyctids. In addition, while I don't know much about clock
construction I would be concerned about chemical affects. Methyl
bromide, for example, affects some metals and is readily absorbed by
red and white oaks, resulting in long-term off-gassing.

But, if methyl bromide isn't used, what is left? Well, there is
sulphuryl fluoride, which is slightly less damaging to most objects.
This, however, is likely no easier for you than your current
fumigation. In addition, sulphuryl fluoride tends to be less
effective against eggs and requires a higher dosage.

You indicate that freezing is inappropriate. The next suggestion
from the museum field would be non-toxic gas fumigation (i.e.,
nitrogen). This is a great technique, but I doubt that it would be
appropriate (i.e., cost effective) for a collector (unless, of
course, there was an institution or a pest control company in the
area which was using the technique already--even this, however, is
not something you can do in your backyard).

I wonder about heat treatments. There is some literature which
suggests a temperature of 49 degrees C (120 degrees F) maintained
for three hours is effective against Lyctids. Would this temperature
be acceptable to the glass, the metals, the wood, the finish, and
the glues? I wouldn't want to expose collections to this temperature
on any sort of routine basis, but perhaps it is less offensive than
chemicals. I'm not sure.

There is also the possibility of treating individual bore holes
using a combination of silica gel and pyrethrum (one such chemical
is Drione). This dust can be injected using a standard syringe.
There is also the possibility of using a borax treatment on the
interior of the clocks. Boron compounds have been found to be very
effective against powderpost beetles. Both of these techniques,
however, assume that you can reach all the interior wood surfaces.

Bottom line, there is no silver bullet or simple treatment. All of
the appropriate options are more or less complex. Those which have
been pushed as simple are now recognized as either very unhealthy
for people or very damaging to the collection or not effective.
Sometimes all three are appropriate, with the perfect example being
the vapona No Pest Strips--carcinogenic, corrosive to metal, fading
fabrics, dissolving glues, and typically not killing insects.

Best wishes,

Michael Trinkley, Ph.D.
Director
Chicora Foundation, Inc.
PO Box 8664
Columbia, SC  29202-8664
803-787-6910

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                  Conservation DistList Instance 10:59
                 Distributed: Monday, December 30, 1996
                       Message Id: cdl-10-59-001
                                  ***