Last year's survey commissioned by the Apiary Inspectors of America found losses of about 32 percent.
As beekeepers travel with their hives this spring to pollinate crops around the country, it's clear the insects are buckling under the weight of new diseases, pesticide drift and old enemies like the parasitic varroa mite, said Dennis vanEngelsdorp, president of the group.
This is the second year the association has measured colony deaths across the country. This means there aren't enough numbers to show a trend, but clearly bees are dying at unsustainable levels and the situation is not improving, said vanEngelsdorp, also a bee expert with the Pennsylvania Department of Agriculture.
"For two years in a row, we've sustained a substantial loss," he said. "That's an astonishing number. Imagine if one out of every three cows, or one out of every three chickens, were dying. That would raise a lot of alarm."
The survey included 327 operators who account for 19 percent of the country's approximately 2.44 million commercially managed bee hives. The data is being prepared for submission to a journal.
About 29 percent of the deaths were due to Colony Collapse Disorder, a mysterious disease that causes adult bees to abandon their hives. Beekeepers who saw CCD in their hives were much more likely to have major losses than those who didn't.
"What's frightening about CCD is that it's not predictable or understood," vanEngelsdorp said.
On Tuesday, Pennsylvania's Agriculture Secretary Dennis Wolff announced that the state would pour an additional $20,400 into research at Pennsylvania State University looking for the causes of CCD. This raises emergency funds dedicated to investigating the disease to $86,000.
The issue also has attracted federal grants and funding from companies that depend on honey bees, including ice-cream maker Haagen-Dazs.
Because the berries, fruits and nuts that give about 28 of Haagen-Daazs' varieties flavor depend on honey bees for pollination, the company is donating up to $250,000 to CCD and sustainable pollination research at Penn State and the University of California, Davis.