Mao Zedong or Chairman Mao had a plan to kill all the sparrows in order to prevent them from eating the food crop. So Communist China dessimated the sparrow population not realizing the ecological catastrophe they had caused. What he didn't realize was that though the Sparrows ate rice, corn and whatever else they also ate parasites and bugs.

Without the sparrows to maintain the parasites they saw their crops get dessimated. And after that the locust population exploded prolonging the problem and creating a famine. Mao's well intentioned plan causes a famine killing an estimated 20 Million people.

Top that.