https://en.wikipedia.org/wiki/The_Mosquito https://en.wikipedia.org/wiki/The_Mosquito > The Mosquito or Mosquito alarm is a hand wound machine used to deter lo

https://en.wikipedia.org/wiki/The_Mosquito https://en.wikipedia.org/wiki/The_Mosquito > The Mosquito or Mosquito alarm is a hand wound machine used to deter loitering by young people by emitting sound at high frequency, in some versions so it can be heard mostly by younger people. > The sound was made into a mobile phone ringtone, which could not be heard by teachers if the phone rang during a class.