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Sorry for the title but don't know how to phrase it exactly.

I once read an article about a period (in France I think but I'm not sure) when the cities were growing and people strted to have issues with rats (I think) that were spreading deseases.

So the authorities decided to pay citizens a sum of money for any dead rat they presented. Thes worked for a period until people figured out they could make lots of money out of this. And so they started raising rats only to kill them later and make the money.

I can't find anything online (don't know what keywords to use) but maybe someone has an ideea on when this happend and where.

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I've edited the title, by I'm also not 100% happy with it. – Darek Wędrychowski Mar 23 '13 at 19:16
@DarekWędrychowski - better? – DVK Mar 23 '13 at 22:58
Much better! :) – Darek Wędrychowski Mar 24 '13 at 7:34
up vote 6 down vote accepted

This happening is known as The Great Hanoi Rat Massacre. It took place in 1902 in Hanoi, which was a French colony at that time.

At the beginning action was a success, but as the bounty was granted for every rat's tail, soon the town was occupied by rats with cut out tails, that were left alive for breeding, and there were more and more rat farms in the downtowns.

You'll find details in "Of Rats, Rice, and Race: The Great Hanoi Rat Massacre, an Episode in French Colonial History" by Michael G. Vann.

What's interesting, the situation when an attempted solution to a problem actually makes the problem worse is called Cobra Effect, which origins come from a similar story that took place in Delhi under British rules, only this time it was about poisonous snakes. What's more, when the government finally decided to stop paying for dead cobras, they were all released alive by breeders, so the population of cobras after the happening was much bigger then previously.

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That was it! Thanks! – john Mar 23 '13 at 21:36
BTW, this was very eloquently covered in "Freakonomics" podcast couple of months ago, with many other examples of Cobra effect (including, very recently, in USA with opigs on military base :) – DVK Mar 23 '13 at 21:50

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