[NHCOLL-L:36] Re: dermestids

[David L Dyer]

Research has shown that a temperature of -20 degrees C for at least 48
hours will kill all life stages of most pests (Florian, M.E. 1986. 
"The Freezing Process - Effects on Insects and Artifact Materials"
Leather Conservation News, 3(1):1-9). However, I have found that some
dermestids will survive at 48 hours so we now routinely freeze for 72
hours, and have found this to work well. Also, to be effective the insects
must not be allowed to acclimate. Thus specimens should not be stored in
any cool environment prior to freezing. The rate of cooling should be
rapid, so allow adequate air circulation around objects; avoid thick
stacks of specimens. Be sure to place specimens in a sealed, polyethylene
bag with as much air removed as possible. This will prevent condensation
on the objects after removal from the freezer. Then, the specimens
should remain in the bag until they have returned to room temperature.
Slow thawing will also help by causing maximum damage to insect pests.
Hope this helps!

Dave

David Dyer, Curator
University of Montana Zoological Museum
  and Herbarium
Division of Biological Sciences
University of Montana
Missoula, MT 59812

On Thu, 18 Mar 1999, Laurel Casjens wrote:

> I am looking for information on temperature/time ratios needed to 
> kill dermestids by freezing.  In either a normal freezer or an 
> ultracold, how long do we need to keep material in the freezer to be 
> sure of killing dermestids and their eggs?
> 
> Has anyone rented a freezer truck to treat quickly a large amount of 
> boxed material?  Did it work?  Are there horror stories?  Is this a 
> reasonable idea?
> 
> Thanks for any help
> 
> Laurel Casjens
> Utah Museum of Natural History
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> Laurel Casjens
> Curator of Collections
> Utah Museum of Natural History
> University of Utah
> Salt Lake City UT 84112-0050
> 
> 801-585-9057
> 801-585-3684 (fax)
> 
> casjens at geode.umnh.utah.edu
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