Slash-and-burn ant eating

The idea is that civilization is a fragile thing, and the reason it prevails is because it's been around for a short time, and even other humans (not to mention animals, which need millions of years to evolve) haven't figured out how to counter it in their control of the landscape. But ants don't rule the insect world, proudly sharing their spheres of influence exclusively with bees and termites. The prophecy is that a method will be devised to smoke out city dwellers in a very small group, and then devour food from storage facilities for several years. And humans with this method of management will quickly wipe out civilizations from most landscapes.