Wouldn't it be much more effective to just kill all their children then? The adults will grow old and die in time. Without children, no new adults. Just kill the kids. Problem solves itself, no?
There will come a time, in the not-too-distant future, when each of us will have to choose sides and grimly set about doing what must be done. Should such a task fall to me, God grant me the determination to see it through rather than go all squishy about how cute they would look in matching sailor suits.