A beekeeper, or apiarist, moves beehives onto a truck to be transferred to another crop after they completed pollinating a blueberry field near Jonesboro, Maine, June 24, 2014. REUTERS/Adrees Latif

Robert Harvey, a beekeeper or apiarist, is illuminated by lights from machinery as he transfers Italian honey bee colonies to fields of crops for pollination, near Columbia Falls, Maine June 23, 2014. REUTERS/Adrees Latif

Beekeeper Robert Harvey crosses over a barricade as he works to transfer Italian honey bee colonies pollinating a blueberry field near Columbia Falls, Maine June 23, 2014. REUTERS/Adrees Latif

Beekeeper Robert Harvey transfers Italian honey bee colonies from a blueberry field to pollinate crops in different fields near Columbia Falls, Maine June 23, 2014. REUTERS/Adrees Latif

Beekeeper Robert Harvey transfers Italian honey bee colonies that were pollinating a blueberry field to another crop near Columbia Falls, Maine June 22, 2014. REUTERS/Adrees Latif

A honey bee, which beekeepers said was an Italian honey bee mixed with an Africanized honey bee, flies near the headlamp of a truck transferring bee colonies to pollinate crops in Columbia Falls, Maine June 22, 2014. REUTERS/Adrees Latif

Beekeeper Robert Harvey transfers Italian honey bee colonies pollinating a blueberry field near Columbia Falls, Maine June 23, 2014. REUTERS/Adrees Latif

Italian honey bees hover around the suit of beekeeper Robert Harvey as he transfers bee colonies from a blueberry field near Columbia Falls, Maine June 23, 2014. REUTERS/Adrees Latif

Beekeepers use a bee smoker to calm colonies before transferring them to another crop after pollinating a blueberry field near Columbia Falls, Maine June 23, 2014. REUTERS/Adrees Latif

Beekeepers use a bee smoker to calm bee colonies before transferring them to another crop after pollinating a blueberry field near Columbia Falls, Maine June 23, 2014. These pesticides have become a subject of scrutiny in Europe and the United States as concern has mounted that they harm honeybees and other pollinators. REUTERS/Adrees Latif

A colony of Italian worker bees congregate outside their hive while pollinating a blueberry field near Columbia Falls, Maine June 22, 2014. Honey bees pollinate plants that produce about a quarter of the food consumed by Americans, including apples, watermelons and beans. REUTERS/Adrees Latif

A beekeeper uses a lift to stack beehives onto a truck before transferring the bees to another crop after they pollinated a blueberry field near Columbia Falls, Maine June 23, 2014. A lawsuit has now been filed by environmental groups in the United States seeking an injunction restricting the approval of a controversial class of pesticides known as neonicotinoids, or 'neonics'. REUTERS/Adrees Latif

Beekeepers secure a cover over bee hives stacked on a truck as they prepare to transfer the bees to another crop after they completed pollinating a blueberry field near Columbia Falls, Maine June 23, 2014. Over recent years, bees have been dying at a rate the U.S. government says is economically unsustainable. REUTERS/Adrees Latif

Beekeepers are seen atop a truck as they secure a cover over bee hives before transferring the bees to another crop after they completed pollinating a blueberry field near Columbia Falls, Maine June 23, 2014. REUTERS/Adrees Latif

Beekeepers, or apiarists, secure a cover over bee hives stacked upon a truck as they prepare to transfer the bees to another crop after they completed pollinating a blueberry field near Columbia Falls, Maine June 23, 2014. REUTERS/Adrees Latif

David Hackenberg, 65, a beekeeper or apiarist, secures bee hives stacked upon the back of a truck as he prepares to transfer the bees to another crop after they completed pollinating a blueberry field near Jonesboro, Maine June 24, 2014. REUTERS/Adrees Latif

Beekeeper, or apiarist, David Hackenberg, 65, rests by the side of his truck at the end of the evening after transferring bee hives from a blueberry field near Columbia Falls, Maine June 22, 2014. REUTERS/Adrees Latif