As Zika virus advances in Central and South America, and more US residents (almost 150 so far) return from the area with infections, public health officials are braced for the next likely step: the moment when Zika passes from a traveler bearing the virus in his or her blood, to a local mosquito, and then to another person. That viral traffic has the potential to ignite Zika outbreaks in the United States in the areas where the mosquito species which carry it already flourish, across the South, in the Mid-Atlantic states and as far north as Des Moines, Cleveland and New York.

And though no one is yet talking about it publicly, that presents an enormous problem. In the United States, mosquito control —