Hi, I'm a botanist and curator of the New York State herbarium. We routinely freeze herbarium specimens to kill cigarette beetles. I've also used the technique on my personal collection of Navajo weavings, just to be on the safe side before adding an item to the collection. I've never noticed any problems with either the herbarium specimens (dried, pressed plants taped or glued to paper sheets) or to the weavings. The herbarium specimens are simply placed in the freezer in stacks. I've rolled and then wrapped the weavings in plastic as you suggest.
The treatment seems to be effective. We don't have any data on effective temperatures nor time intervals for cigarette beetles, but for dermestids, the accepted treatment is -20 C for a minimum of 4 days. Our freezer goes to nearly -33, and I tend to put the stuff in for a couple weeks, just to be safe.
The main problem in terms of efficacy is diapause. Most of the insects are probably actively reproducing, but it is possible, especially at this time of the year, that some might become dormant in preparation for winter. They then might survive the cold treatment. With particularly dirty herbarium material, then, after a few weeks in the freezer, I move them to a heated cabinet at about 35-40 C for about 5 - 7 days, then return them to the freezer. I hope that any diapausing insects would become active in the heat, and then be killed by the return to the freezer. I don't know that this would actually work, but it is simple enough to do.
Good luck,
Chuck Sheviak
Curator of Botany
New York State Museum
Albany, NY 12230
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Hello. I was hoping to get feedback from those of you who have experienced
freezing textile collections to kill pests.
A few months ago we discovered live carpet beetles (and plenty of dead ones)
in our costume/clothing collection (95% dresses, mostly from late 19th c.,
mostly silk or cotton) . Our pest control people need us to clean
everything out of our three infested, small textile/costume storage rooms so
that they can do a "crack and crevice" treatment. In the meantime, we plan
on freezing our costume collection to kill the pests. This is our plan:
--place each item in a thick poly bag, making sure to pad the shoulders and
folds with acid free tissue. Try to get out all of the air without
squishing the textile. Seal bag.
--place a few bags in a box; seal, label, and inventory the box.
--place box in freezer for two weeks to kill the pests (the local grocery
store is donating space in their huge freezer which maintains a constant
temp way below freezing). We will have about 25 boxes of textiles to
freeze.
--remove box after two weeks and keep in cool room until we place the
textiles back in the pest-free storage rooms.
These are my basic questions:
--should I freeze the textiles for two weeks? what is the minimum amount of
time to freeze pests so they die?
--should I take special precaution with freezing costumes made of certain
materials?
--is there a rust danger when freezing and thawing costumes that contain
metal elements (like buttons, clasps, etc.)?
--anything else I should know or be aware of before implementing my plan?
Sincerely,
Jarrod Diels-Roll
Curator
Pejepscot Historical Museums
159 Park Row
Brunswick, ME 04011
207-729-6606
207-729-6012 (fax)
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