It's called the Cobra Effect. In colonial India, under British rule, the city of Delhi had a problem with cobras. To control the cobra population, the government offered a bounty for every dead cobra. Huge numbers of dead cobra were handed in but the cobra problem got worse, not better. Why? Because people realised they could profit from this bounty by breeding cobras, not to kill them in the wild, but to kill them for the bounty. This turned into a small-scale cobra farming operation. When the government became aware of this practice, they discontinued the bounty program. Without the incentive, the cobra breeders released their now-worthless snakes into the wild. As a result, the cobra population in Delhi ended up increasing rather than decreasing, exacerbated by the government's own policy.