Shimla (HP), Sep 07 (ANI): Himachal Pradesh declared monkeys as menace and took up a sterilisation drive. It has proved to be ineffective as monkeys continue to attack farmlands and residential areas. A farmer complained that the menace caused by the monkeys are the most in the villages of Pujali, Dhamichi and Kuwara. Even after sterilisation the population of monkeys are nearly 150,000. This problem will continue for the next twenty years because the average lifespan of a monkey is 20-25 years.