Oxitec is trying to leverage this mating instinct to help wipe out one particular species of mosquito: Aedes aegypti, carrier and spreader of some of the worst insect-borne diseases known to medicine—dengue, malaria, and Zika. The A. aegypti mosquito has evolved to survive even the most effective pesticides. It can lay 500 eggs in just a bottle cap’s worth of water, and it prefers to bite humans over animals, so it lives in places where no one thinks to spray, like under the couch. ... The idea behind Oxitec’s experiment is that if enough genetically modified male A. aegypti mosquitoes are released into the wild, they’ll track down large numbers of females in those hard-to-find places and mate with them. The eggs that result from any union with an Oxitec mosquito will carry a fatal genetic trait engineered into the father—a “kill switch,” geneticists call it. The next generation of A. aegypti mosquitoes will never survive past the larval stage, never fly, never bite, and never spread disease. No mosquitoes, no Zika. ... Oxitec is far from the first company or research team that’s tried to sterilize an entire insect population. Scientists have been going after A. aegypti in this way since the 1970s, usually by irradiating them. The problem with radiation is that it makes the mosquitoes too weak to get out and breed. The great innovation of the Oxitec method is that it cleverly achieves the same result as sterilization, while leaving mosquitoes able to do what mosquitoes do. ... Oxitec charges about $7.50 per person per year in each area it treats.