cruiser came to this apartment in nearby yonkers, new york, and sure enough -- >> good boy. >> so, helerts. you can let the dog sniff around. they are pace back and forth until they pick up on the scent. >> i couldn't believe that a little dog like that knew exactly where they were. okay. >> reporter: it's nina's bedroom that's infested. >> see, the arms, to down here. >> reporter: she showed us the tiny red bite marks covering her body. >> they hit anywhere. >> they hit anywhere. they don't have a preference. >> reporter: for nina and the millions of other bed bug victims nationwide, the question victims nationwide, the question is, why now? the insects were all but eradicated a half century ago with the help of ddt, but ddt has since been banned in the u.s. over health, environmental u.s. over health, environmental and other fears. >> well, actually never were completely gone. they were probably in low populations in various cities. >> reporter: louis sorkin knows all about the insects. >> the populations were able to increase invisibly. >> reporter: new york's authority on the crea