An 'Odd' discovery...

[Robin Leech]

An old trick we have used in western Canada is to put the critters and
infested material into an air-tight chamber.  Flood the chamber with
CO2.  One of the easiest sources of CO2 to use is dry ice.
The CO2 causes the pests to open their spiracles wide - wide
- and they cannot close them when you introduce the next poison.

Give the CO2 treatment for a 15-24-h period, then drop in the real
toxin - cyanide gas for 24 h, and 48 h for the PDB.

Because they are now forced to keep their spiracles wide open, the
PDB or CN gas goes straight in.

After a 24-h period with CN gas, or perhaps 48 h with PDB, open
and vent the chamber to the outside.  All the critters will be dead.

Robin