Download at: http://itunes.apple.com/app/ultrasound-killer/id469459961?mt=8
New App released, Ultrasound Killer is a Mosquitoes & Rats repellent, it works with a certain frequency ultrasounds.
Surely you do not find an application as easy to use.
How to? Press “On” to activate a repellent and use the volume keys to configure the effectiveness.
More volume is equal to say more effectiveness because the sound waves travel farther so the radius increases.

;)
Here you can see a video demostration: