Mysterious 'Colony Collapse Disorder' Threatens Food Chain

Three times in the past 120 years, honeybees have disappeared for mysterious reasons. Twice since the 1980's, there have been infestations of bee-killing mites. But those episodes have been restricted to limited areas. Since last November, tens of billions of honeybees all over the country are flying away from their hives and never returning. Bees pollinate hundreds of fruits, vegetables, flowers and nuts worth $14 billion, and scientists have no idea why so many are disappearing.  Is there another way to pollinate?  Is the disappearance of honeybees related to genetically engineered crops?  We talk with a beekeeper who's lost 60% of his insects and get a report on a two-day conference of bee experts investigating what's now called "colony collapse disorder."