Mosquitoes
Octenol
When people and animals breathe, they exhale mixture of carbon dioxide and octenol, which is actually a type ofalcohol. Octenol is sometimes described as 'cow’s breath in a can', and is a remarkable lure for mosquitoes. Mosquitoes and other biting insects have extremely-sensitive receptors that can detect this chemical from almost 100 feet away.
Body heat
Circulating blood in animals and humans radiates body heat. As mosquitoes have sophisticated heat sensors, they follow body heat and exhaled gases and fly to their target. The exact temperature depends on the type of mosquito.
Moisture
During breathing people also exhale water vapor and perspiration is produced during active movement. Even small amounts of water will attract mosquitoes as it could mean possible blood source or possible breading site.
Movement
Mosquitoes can see their victims from within 30 feet by locating the changes in waves of light around them, caused by moving objects.