According to an ongoing study called the National Cockroach Project, the roaches of three NYC neighborhoods—the Upper West Side, the Upper East Side, and Roosevelt Island—are genetically distinct. Like many of the city's humans, each group tends to stay in its own neighborhood. And, since American cockroaches originated overseas, these urban insects can also claim immigrants as ancestors.

To find out more about what's bugging the Big Apple, we sat down with the project's lead scientist: Mark Stoeckle, an infectious-disease specialist and senior research associate at the Rockefeller University's Program for the Human Environment.

We'd been working with high-school students using bar coding, which is a simple way of identifying species by DNA. And one of the projects a couple