On its own terms, this campaign was a massive success: it appears to have driven the country’s sparrow population to the brink of extinction. But sparrows don’t eat just grain and fruit; they also consume insects. With the threat from natural predators vastly reduced, the locust population boomed and then feasted on the harvest in a manner far more destructive than anything that sparrows could have achieved. In this way, the campaign to “exterminate the four pests” contributed to the famine that killed 45 million people during the Great Leap Forward.
