Date Time How One of Oldest Natural Insecticides Keeps Mosquitoes Away The Aedes aegypti mosquito, which can spread dengue fever, Zika virus and yellow fever. New research shows mosquitoes are able to “sniff out” trace amounts of insecticides using specialized receptors on their antennae. Photo by James Gathany, CDC DURHAM, N.C. — With mosquito season upon us, people are stocking up on repellents to prevent itchy bites. Bug repellents are important because they don’t just protect against the buzzing, blood-sucking little pests — they also safeguard against the diseases they carry, which kill some 700,000 people worldwide each year. Surprisingly, despite widespread use, no one understood exactly how most mosquito repellents keep the insects away. Now researchers are starting to uncover the first pieces of the puzzle.