“No bees, no blueberries,” said David Yarborough, the University of Maine Cooperative Extension Service’s wild blueberry specialist.

Field studies done in Washington County and elsewhere in Maine have shown that yields can be increased by as much as 1,000 pounds an acre for each hive servicing that acre, up to five hives per acre. Those results presume good weather, adequate soil moisture and good fertilization and pest management.

“There are usually about 55,000 hives trucked in each spring from places as far away as Florida, Texas and California,” Yarborough said. “With anywhere from 20,000 to 40,000 bees per hive, that’s a billion bees. But, when it’s cold, wet and windy, like it has been lately in Washington County, they’ll stay in the hive and try to stay warm. When it’s sunny and warm and calm, they’ll work very hard.”

On Thursday, the sun finally burned through three days of rain, fog and drizzle, boosting daytime temperatures in Washington County’s blueberry barrens by almost 20 degrees.

“The hives have been out there maybe eight or nine days now, but there’s been only a couple of days of decent weather,” Nat Lindquist, vice president of operations at Wyman’s of Maine, said Thursday morning. “They’ll be out today and, for the next few days of sunshine, and they’ll be hungry and angry.”

Maine has 60,000 acres of blueberry barrens, with only half of those acres in production any given growing season, given a two-year cultivation cycle. Milbridge-based Jasper Wyman & Son is the largest of the six companies in Maine that process, freeze and can wild blueberries, There’s also one fresh-pack cooperative. Most of Maine’s wild blueberry fields are clustered in the Down East and midcoast regions of the state. An estimated 99 percent of all the berries harvested in Maine are frozen for use as a food ingredient.

Frank Drummond is an entomologist and a blueberry pollination expert who literally wrote the book on the subject while teaching within the University of Maine Graduate Program in Ecology and Environmental Science. He notes in his magnum opus on bees and blueberries that the cost of renting hives can be a blueberry grower’s single most expensive management practice, but it also is a practice that usually results in higher yields.

Lindquist won’t disclose how much Wyman’s spends on renting hives, but Yarborough said growers are paying rental fees of between $90 and $100 per hive, up from $60 to $70 a hive a few years ago. That was before an era of higher transportation costs and lower bee populations due to “colony collapse disorders” that decimated bee populations and required beekeepers to rebuild their stocks. “But even at 50 cents per pound [last year’s blueberry price was 85 cents], a hive will produce an additional 1,000 pounds [of blueberries],” Yarborough said. “So that’s $500 a hive on a $90 investment.”

Lindquist said the hives Wyman’s rented this spring arrived on trucks from Florida, Louisiana, Pennsylvania and Texas.

“The cost of hive rental has more than doubled in the last six or seven years,” he said. “And with the spikes in diesel prices, we’ve been paying a fuel surcharge. We group the hives in about a dozen ‘bee yards’ throughout the barrens. Some might have 50 to 60 hives, others up to 200.”

The bees will remain at work for another three weeks, Lindquist said. “It all depends on the weather, but it will probably be June 10 before they’re gone.”

Drummond notes that timing is everything, involving factors such as weather over which growers who contract for hives have no control. Ideally, trucks loaded with pallets of hives arrive and the colonies get to work when 15 to 25 percent of the bloom is on the bush.

“If they come too early,” Drummond says, “the bees may fix on other flowering plants and may not switch back to blueberries. If they come too late — 50 percent bloom or later — the earlier blooming clones will not be pollinated.”

Native bees are more productive pollinators than honeybees from away, said Drummond, who has been raising bees since he was age 13. He was recently awarded a $3.5 million federal grant to study Maine’s native bee population at 16 blueberry growing operations in Washington and Hancock counties.

Existing field research, he said, has shown that a single native bumblebee is 2.3 times more efficient as a pollinator than a single honeybee from away. Native bumblebees will “work” in cold and wet weather that honeybees won’t. Having evolved in Maine over hundreds of thousands of years, interacting with lowbush wild blueberries, the natives have perfected in-flight and harvesting techniques for quickly and thoroughly extracting pollen from the wild blueberry flower.

“The bumblebees work three times faster than honeybees,” Drummond said. “And, while a honeybee might inadvertently get one to three grains of pollen while looking for nectar, a native bee will get 20 grains or more.”

Yarborough said another expense of maintaining hives is damage from bears. “The bears in Washington County are just coming out of hibernation, and they’re hungry,” he said. “It’s not like Winnie the Pooh going after honey. The bears will rip the hives apart to get at the protein in the brood [young bees]. That’s why almost every cluster of hives you’ll see in a field is surrounded by electric fence.”

Lindquist said bears are more of a seasonal nuisance than a wrench in Wyman’s operations. “The electric fences help,” he said. “But, if a bear is bound and determined to get to the brood, nothing will stop it.”

Maine’s 2011 wild blueberry harvest tipped the scales at 83.1 million pounds, according to yield results calculated by the U.S. Department of Agriculture. That was 100,000 pounds more than the 2010 crop, which the USDA estimated at 83 million pounds.

While the last two crops were virtually identical in yield, prices paid to growers were up significantly in 2011, jumping from 61 cents per pound in 2010 to 85 cents per pound last year. At that price, Maine’s 2011 wild blueberry harvest was worth $70.1 million, or 42 percent more than the 2010 crop. Midcoast growers saw lower yields per acre than their Down East counterparts due to wet weather during spring pollination and a lack of rainfall during the run up to harvest in late August.

The 2011 wild blueberry crop in Canada weighed in at 132.3 million pounds, up from 125 million pounds in 2010, Yarborough said. The USDA estimates that the total U.S. blueberry crop in 2011 was 428 million pounds, including 345 million pounds of cultivated berries. Oregon accounted for 65.5 million pounds of the cultivated berries, while growers in New Jersey and Georgia had yields of 62 million pounds in each state.