Mother Nature Network: Youve probably heard that honeybees in America had a particularly difficult time this winter, with hive losses surpassing 50 percent in some areas. Colony collapse disorder or CCD is blamed for doubling or tripling the usual rate of winter hive die-offs, and years into the epidemic, scientists are still scrambling to understand the cause or causes. Linkages have been found between CCD and a number of factors, but a single, smoking, bee-killing gun remains elusive. Lets take a look at some of...