New York City Mayor Bill de Blasio is on a campaign to wipe out the large populations of rats that plague the city and, in particular, some of the city’s housing projects. Yesterday, he gave a presentation on his plan while sitting behind a large sign that read "Watch Out Rats!" "We love our city but our city is associated for many generations with the problem of rats," de Blasio said. He then outlined a new approach to the problem which involved the use of dry ice to humanely suffocate entire rat colonies in their burrows. In order to demonstrate...