Some apps claim to imitate the wingbeat frequency of dragonflies or bats, which are natural mosquito predators.
Most "anti-mosquito" downloads claim to repel insects by emitting —high-frequency tones (usually between 10kHz and 20kHz) that are often inaudible to adult humans but supposedly irritating to pests. Common theories used by developers include: anti mosquito download
Others claim to mimic the sound of male mosquitoes to repel pregnant females (the ones that bite), though research shows females are largely indifferent to these sounds. Does It Actually Work? Some apps claim to imitate the wingbeat frequency