If you have an iPhone, then with a few clicks and for free, you can download and try the ultrasound repellent application "No! Mosquito!" developed by the Cursor Plus MB team.
This app creates the sonic waves and pulses that humans can't hear, but the mosquitoes do. As you may know, mosquito males are not blood eaters, only the female mosquito bites and only when she has eggs inside her body. She needs human blood that allows her to mature these eggs. At that time mosquito female don't want to meet mosquito males, because she is already fertilized. By changing application parameters you can simulate mosquito male buzzing sound so mosquito females will go away.
It's easy to work with the "No! Mosquito!" application. Press the big "power" button and you will see how the app will change from the static view to the illuminated "buzzing" mode. Because the waves are almost inaudible, it's clear when the app is working. Change the frequency range from 14 to 22 kHz and you will find the "best working spot" for your environment and your mosquitoes. Keep the volume high for better protection. You can change parameters easily and next time the application will remember what you have chosen. I found that I can hear 14 - 15 kHz waves so I decided to change all modes to higher than 16.5 kHz frequency because it's better to sleep when you can't hear that noise. It's good to have a timer as you don't need to worry about closing the app. It will turn off the session for you automatically.
On the market, there are a few applications like this, but those lack advance functionality and look amateurish. Most of them have a background mode only in the paid version, so with the free version you will drain your battery because the screen will remain lit all night long. "No! Mosquito!" app has this background mode for free.
If you want to have a stylish and more functional anti-mosquito app in your phone, we suggest you to try this application. For no cost you will get all the functions that other developers are offering in their paid versions (background mode, full scale 14 - 22 kHz sinus wave ranges, and timer). Two color skins you will get for free too. For an additional $0.99 price, you will get the extended smart mode and the auto mode algorithms for your better protection. Plus you will get the presets where you can save different parameters and play all these together during an audio session.