When I first started out in preparedness food storage, I read somewhere that many long-term storage folks have a dry ice solution. It not only kills critters, but it helps remove oxygen from the container, which increases storage time. They use white food grade puckets with screw on lids, fill the containers to about two inches from the top, and then fill that last two inches with dry ice. Seal the container with the screw on lid, and almost immediately the critters and their evil spawn are frozen to death. As the dry ice reverts to a gas, it replaces any remaining oxygen in the container.
Thought that was a cool idea, and might be of benefit to someone !