Photo: CDC/PHPPO/DPDE/CAB/PhotoServices/James Gathany

For 50 years, it's been a ritual. People heading outdoors first coat themselves in a layer of DEET to fend off mosquito attacks. For backyard barbecues, a 25% DEET formula may do. Head into the woods or go fishing on a lake, and you'll need something closer to 50% strength. Despite our hesitation to apply something that seems so toxic to our skin, we do it. Why? Because it works.

Now we know for sure why it works, thanks to a study completed at Rockefeller University. Mosquitoes simply can't smell us through the scent of all that DEET. The bloodthirsty tormentors find us with keen olfactory sensors that detect human sweat and carbon dioxide that we exhale. The smell of DEET simply overpowers their senses, making our bodies somewhat invisible to the mosquitoes.

What do you use to keep mosquitoes at bay?