ELBOW LAKE -- In a sprawling bee yard, beekeeper Steve Ellis, wearily surveyed 1,300 hives destined for fields across the countryside.
Given bees pollinate fruits, vegetables and nuts, and pollination is required for about one third of all food production, he should be enthused about their summer journey.
But as Ellis knelt in front of a hive to inspect it, he had cause for concern. Many of the bees were in no condition to pollinate plants and make honey. Indeed, drifts of decomposing bees covered the ground.
"From a beekeeper's standpoint, it's a nightmare," Ellis said. "Dead bees everywhere."
The problem isn't an isolated one. Across the nation, large numbers of bees — about one third of colonies each year — have been dying for the past six years. Scientists believe the cause is a combination of pesticides, disease and poor nutrition, and some are concerned the annual bee losses are unsustainable. As soon as this year, some warn, there might not be enough bees to pollinate some crops.
As Ellis lamented the rotten odor of dead bees, which close to the hive he said "smells like death," a single bee struggled out of the hive dragging a dead bee.
"It's actually a good sign some of the bees have enough wherewithal to carry dead bees off now," he said. "For about a week they were so impaired they couldn't even carry the dead carcasses out, they just piled up."
So what killed millions of bees in this bee yard?
The Minnesota Department of Agriculture, Bayer Crop Science, the University of Minnesota and Purdue University are all testing the dead bees, said Ellis, who thinks they were killed by a Bayer Crop Science insecticide from a nearby farm field.
During the winter, Ellis takes his bees to California to pollinate almond trees. He recently trucked the hives back to Minnesota and was at his bee yard preparing the hives to be placed in fields around the region when bees started dying.
A farmer was planting corn on a nearby field that day, and the wind blew clouds of dust over the bee yard. Ellis thinks that dust carried a toxic mix, as the seeds were treated with neonicotinoid insecticide.
According to pesticide industry reports, more than 90 percent of corn seeds planted in the United States are coated with neonicotinoid insecticides.
Systemic insecticides are taken up by the growing plant, so the chemical is inside the corn plant, ready to kill any pest that munches on the leaves, stalk or roots.
Bayer Crop Science sent a team to collect samples of dead bees, Ellis said. The company did not respond to an interview request.
Neonicotinoid insecticides are used on more than 150 million acres of crops. As the seeds are being planted, the insecticide attaches to dust and drifts on the wind.
"Beekeepers in Ontario and Minnesota and Iowa and New York and all over the corn belt are reporting these kinds of problems," said Ellis, a member of the National Honey Bee Advisory Board, an organization formed by bee keepers to address bee losses. "We think it represents an unreasonable risk that EPA should be able to recognize."
Beekeepers have asked the U.S. Environmental Protection Agency to restrict the use of neonicotinoid insecticides. Earlier this year, the European Union imposed a two-year ban on three neonicotinoid insecticides after the European Food Safety Authority identified "high acute risk" to bees.
One area of concern identified by European regulators is exposure to bees during spring planting.
In response to that ban, the EPA said there is not enough scientific evidence to impose similar restrictions in the United States. The agency is reviewing the registration of neonicotinoid insecticides, but that review is expected to take several years.
Ellis has been fighting government agencies and agri-chemical companies since his bees starting dying in about 2006. He is one of several beekeepers who sued the EPA earlier this year seeking a moratorium on the use of neonicotinoid insecticides while the agency conducts an environmental study of the insecticides. The EPA does not comment on pending litigation.
According to Ellis, about 60 percent of his bees died during the past winter. After losing so many earlier this month, he won't have enough bees to put all of his hives out this summer, and the hives he does set out will only have about half the normal number of bees.
Bees are dying in large numbers around the world.
Scientists and apiarists disagree over exactly what's happening, but there is consensus that disease, nutrition and pesticides create a worst-case scenario for bees. A growing body of scientific research shows even very low levels of neonicotinoid insecticide exposure can affect bee behavior.
Vera Krischik, an associate professor of entomology at the University of Minnesota, notes bees are very social insects with a complex communication system. For insects, bees have a big, well developed brain, and neonicotinoid insecticides work by blocking neurons in the brain, she said.
"Very low levels are affecting foraging. That to me is the huge issue," said Krischik, who is publishing three years of research on bumblebees and honeybees. "Bees can't find their way home. You know, if you can't go out and collect pollen and nectar and you can't bring it back, then a colonial insect is going to have a big problem."
However, it's not just farm fields that are affecting bees.
Neonicotinoid insecticides are ubiquitous in urban backyards. They protect flowers, shrubs and trees from pests.
The insecticide dose on backyard plants is much higher than what is used on farm crops, said Krischik, who found the insecticide that protects a rose bush or an apple tree also is deadly to bees who come to drink nectar from the flowers.
"I start to see a significant number being killed at the regular landscape rate," Krischik explained. "And when I add twice the rate, because you can use this product more than one time a season, the bees die in the flower. Just one sip kills them on the spot."
The next question for researchers is to understand how much neonicotinoid insecticide bees are exposed to across the landscape, Krischik said. But she can't answer that question because she has no money to continue her research.
A year ago, the Minnesota Legislature blocked a grant Krischik received from the Minnesota Legislative Citizen Commission on Minnesota Resources to study how treating trees for Emerald Ash Borer is affecting bees.
This year the Legislature passed a pollinator habitat bill. It appropriates $150,000 per year to improve bee habitat and increase public awareness of pollinators. The legislation also requires state agencies to create a report on pollinator habitat, and establish a process for reviewing the safety of neonicotinoid insecticides.
The legislation reflects a growing public concern about bees, said Marla Spivak, a Distinguished McKnight Professor in University of Minnesota's entomology department.
"The progress is going quickly now. Even this pollinator bill passed in our legislature this session is just amazing. This would have never happened three years, five years ago. So now I think we'll see some positive change," Spivak said. "But right now, honeybees are really, they really are at the tipping point right now."