Mosquito bites itch, become red and swollen, and the longer you scratch to relieve the symptoms, the worse they get. Once the bite is there, it's too late. You need to take action beforehand. This repellent plug emits a high-pitched sound that mimics the wingbeat of mating male mosquitoes. Fertilized, blood-sucking female mosquitoes react negatively to this sound and try to leave the area where it can be heard. The device has a discreet and modern design and is sized to fit a standard power outlet.