freezers for insect control in museums

[Fewless, Gary]

Thanks to everyone who responded to my questions about the use of freezers
to control museum pests.  In spite of the frustration of some at enduring
another round of discussion on a topic that has been around before, I think
it was very useful.  There is something to be said for a sampling of the
methods that people are actually using, and the use of freezers to control
pests is not so old that we have adopted any actual "standards".  Indeed the
answers I received were extremely diverse.

Responses ranged from about -20 to -80 F and time of treatment from 2-3 days
to a month.  It seems that each institution has adopted some set of
compromises involving the effectiveness of the temperature used, the time
treatment must be applied, and cost to own and maintain, among other
considerations. In general the warmer temperatures require longer
treatments, up to weeks or a month in length.  Colder temps (-80F) might
require only a few days, but there is some concern that this extreme
temperature can break down associated materials of mounts, etc.  If a large
volume of material must be treated (and for many institutions treatment is
continuous, beginning again when the last item has been processed) the
longer time of treatment would be unacceptable.  Another important
consideration is the size of the specimens treated.  Larger items may
require several days just to ensure that the interior portions have reached
the target temperature--treatment time can only begin after this point.

Thanks again to everyone.  I am continually impressed by the helpful tone of
this group.

Gary Fewless