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Subject: Silverfish


From: James Hay <james_hay>
Date: Tuesday, June 19, 2007
Holly Chase < [at] sunrider__com> writes

>Does finding one silverfish and a few dead moths justify treating
>all the artwork and cases in that gallery?

I'd say, yes. As a rule of thumb in regards to insect infestations,
no insects is better than a few live or dead ones. No insect damage
being the goal, a total absence of live or dead insects is the
route. If you don't have one, you ought to begin a program of
integrated pest management (IPM) now. On one hand, it could be that
the insect you found is only a random, single intruder from
outdoors, but on the other hand, you may have discovered an
enterprising individual insect who strayed from the central feast
that is a glue joint in one of your hangings. You won't know which
until a thorough, knowledgeable search fails to find an infestation
anywhere in your collection.

Pheromone traps might be a good idea somewhere within the museum,
but not necessarily within the showcases. You definitely do not want
to lure pests into the showcases or storage cabinets. You must begin
searching through your facility and the collection for any other
insect life. You must empty, sweep and vacuum, and clean your
showcases, you must begin mapping the facility to identify where you
are going to place your lures and/or traps, then identify, date, and
install the sticky traps and/or lures, and then begin monitoring
whatever kind of insect presence you discover in your lures and
traps. Are numbers trapped on the rise? Begin with a weekly
inspection; after a month without exciting finds, perhaps monthly
sweeps will suffice. As one of my esteemed colleagues says, you have
to think of insects like a gas: they can go anywhere, and you cannot
keep them out of a museum. You simply must be determined, organized,
and perseverant in trying to find and eliminate them. They're very
good at hiding, as you know.

"Anoxia" means without oxygen; all stages of insect life can be
suffocated if deprived of oxygen for about two weeks. The anoxic
method we use here tends to be carbon dioxide, which works well and
is not too expensive.  I believe many American museums use nitrogen
chambers instead, to avoid contributing CO2 to the environment.
Whatever the method, I imagine that the famous museums in southern
California either have fumigation chambers themselves or engage
private firms that fumigate anoxically for them, and they ought to
be able to suggest who can fumigate your collection for you. Anoxic
fumigation leaves no poisonous residue that might damage your
collection. The downside of the absence of a poisonous residue is
that there nothing to stop re-infestation, except for your continued

As for eliminating insects hiding within a built-in showcase, you
can be sure it isn't easy. If the showcase was removable, you could
anoxically fumigate it as well.  For a built-in unit, I think all
you can do is clean it very well with a brush and vacuum. Perhaps
you can also paint it on the inside with a paint approved for
display case interiors. The smell ought to kill a few insects.
Perhaps you can find a kind of caulking that is not dangerous to
artifacts, and you can seal all the little cracks between showcase
and wall. After painting and caulking, the showcase will have to air
out for some weeks to allow offgassing to mostly end before you
reuse the showcase. Some old museums have come to terms with
historically interesting, if insect plagued, built-in display cases,
and accept a low level of insect activity as the price of continuing
to use the showcases. They continue to use sticky traps inside the
cases, in spaces out of sight from the public and separate from the
volume containing the display material, to trap and destroy insects.
They avoid poisons, owing to the danger to the public, staff, and
artifacts. Sticky traps kill, too.

Museum pest control is a big subject with its own discussion group.
These are just some tips.

As another rule of thumb, I am guessing that, if you rigorously
clean and trap and monitor insect activity for six months in all
showcases, storage areas, loading docks, areas where food is
consumed, offices, entrance areas, and so on, without finding one
more protein-eating museum insect pest, then you probably do not
have an active infestation. You might still have one, but that is a
pretty long time for an insect colony to exist without an
adventuresome individual insect wandering off and getting caught in
one of your traps. The danger is that one normally finds the damage
before one finds the pests. If I were you, I'd reinvigorate your IPM
program now and vigorously sustain it. I  hope you enjoy reading
more about IPM, and good hunting.

James Hay
Senior Conservator
Furniture and Decorative Arts
Canadian Conservation Institute
1030 Innes Road
Ottawa Ontario K1A 0M5

                  Conservation DistList Instance 21:12
                 Distributed: Wednesday, June 20, 2007
                       Message Id: cdl-21-12-002
Received on Tuesday, 19 June, 2007

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