Russian scientists travel to Sahel to test most effective mosquito repellents.

Why the Sahel? 

"To verify the actual effectiveness of protective devices, we went to the heart of the malaria epicenter, where mosquitoes are particularly aggressive and number in the thousands," said Roman Yakovlev, the study's lead author and a Russian researcher.

Results:

Most effective: Electronic heating devices proved to be the most effective. According to the researchers, they create an invisible protective "dome" around them, within which mosquitoes either lose their ability to detect hosts or die while flying.

Less effective: Smoke coils, scented candles and ultrasonic devices performed significantly worse.