More than a quarter of the country’s 2.4 million bee colonies have been lost — tens of billions of bees, according to an estimate from the Apiary Inspectors of America, a national group that tracks beekeeping. So far, no one can say what is causing the bees to become disoriented and fail to return to their hives. As with any great mystery, a number of theories have been posed, and many seem to researchers to be more science fiction than science. People have blamed genetically modified crops, cellular phone towers and high-voltage transmission lines for the disappearances. Or was it...