First, they gathered piles of mosquitoes' favorite nectar-producing plants and analyzed the chemical makeup of each flower's fragrance. They exposed mosquitoes to individual elements of each fragrance to find out which ones got their attention, then eliminated any scent that also brought bees to the yard. The final result was an intoxicating perfume of sugars and proteins that no mosquito could refuse.
— Read more at Floral-Scented Pesticide Lures Mosquitoes to Their Death at Mental Floss.