As sterile male mosquitos, that is.
From The Guardian: "Male mosquitoes don’t bite or carry disease. One of the main approaches Google is testing involves rearing male mosquitoes with a naturally occurring bacteria, called wolbachia, which stops them from having offspring with wild female mosquitoes. When an infected male tries to mate with a wild female, her eggs won’t hatch; Google explains in a blogpost: 'the population gets smaller with each generation.'”