Re: Specimen fumigation
 
   The last few messages on modes of fumigation of dry preserved
specimens make some interesting observations, but I have seen nothing
to indicate what pests are being the problem, if any.  I presume that
insects are the main culprits, likely one or more species of dermestid
beetles.  However, booklice (not true lice), cockroaches, and other
critters can be equally devastating.
   Freezing and inert gas fumigation are both viable alternatives to
more typical pesticides, but both have severe limitations requiring
accurate determination of the pest at hand.  For example, dermestid
beetles, depending on species, can tolerate normal deepfreeze temps
for many hours, even days.  Also, even if you freeze for a 3-4 days
or a week, the adults and larvae may have been killed, but not
necessarily the eggs; again, depending upon exposure duration.
Similarly, inert gas use is not defined, but CO2 or N2 have their
exposure limits as well.  If short duration, the beetles will simply
close their spiracles and await breathable air.  Eggs can tolerate
extremely low O2 concentrations for long periods of time; thus, repeated
treatments may be necessary.
   The failure to begin with proper pest determination can cause
serious problems in the museum, as much as in the crop field.
 
==========================================
Paul J. Johnson
Assistant Professor & Curator
Insect Museum, Box 2207A
South Dakota State University
Brookings, South Dakota 57007   USA
e-mail: [log in to unmask]
==========================================
"By every conceivable measure, humanity is ecologically abnormal."
                                          - E.O. Wilson
                                            The Diversity of Life