Rat bounties were common at the beginning of the twentieth century as a way to rid cities of disease and infection due to rats. In the wake of the 1906 West Coast plague Portland instituted a widely publicized rat bounty. How was it implemented? And did it work?
There is a good deal of reason to doubt that the bounty would be effective. One of the most famous bounties, in Hanoi, is widely cited as an example of Perverse Incentives: the high bounty led potential claimants to breed rats, and did not reduce the rat population.