The Cobra Effect?
There is an interesting anecdote about the British rule of India. Worried about the large number of venomous cobras in the Indian city of Delhi, the British government had a brilliant idea: they offered a reward for every dead cobra. While this initially resulted in people killing cobras to claim the reward, it soon resulted in unforeseen problems for the British. People began to breed cobras to claim the reward. When the British realized this, they scrapped the reward program. The people then released the worthless snakes, resulting in an increase in the cobra population. The efforts taken by the British to solve the cobra problem had actually exacerbated the situation.