I used sugar and yeast for my planted aquariums as well it works fantastic for that. Never had to worry about a regulator sticking and overdosing the fish as happened to several on the planted aquarium forum.
I wonder if you made several CO2 reactors and aimed them into an enclosed space if you could get more a higher ppm in the environment to kill the pests.
Neat dry ice directory, sure aren't many sources around here! LOL