Even so, the USDA's survey of beekeepers found that nearly a quarter of the bees in managed honeybee colonies—a total of 23.2 percent nationwide—perished from October 2013 to April 2014.

That was far better than the average annual loss of 29.6 percent reported since 2007, and the 30.5 percent loss recorded during the winter of 2012-2013. But it's appreciably higher than the threshold of 18.9 percent losses that beekeepers consider economically sustainable, the USDA said.

"This year's survey results, while encouraging, do not provide much comfort because it is not known why the bees seemed to do better this past winter than previous winters," said Gene Robinson, director of the Institute for Genomic Biology and an entomology expert at the