The Aedes aegypti mosquito transmits deadly viruses like Zika, chikungunya, and dengue, but doesn't actually get sick from the diseases it carries. George Dimopoulos of the Johns Hopkins Malaria Research Institute talks with Stephanie Desmon about a new discovery of a protein, Argonaute 2, that plays a key role in the mosquito's immune system, and how genetically modifying mosquitos could make them vulnerable to the viruses they carry. They also discuss how much of an impact killing off large numbers of mosquitos would have, both on the burden of disease and larger ecological balance.