Vast honeybee colony losses during the winter at Fran Motichka’s farm puzzle him.

“I had 20 and I lost 19,” Motichka said as he knelt beside two occupied box hives in a field on his property, about 2 miles northwest of Hamlin Corners.

A half-dozen empty hives stood silently against a stone wall about 150 feet away.

Motichka, 56, who cultivates vegetables and apples, sells hay and raises beef cattle and chickens, discovered the setback in January.

Some 750,000 honeybees had either died or disappeared since he last checked the hives three months earlier.

“About half of them died in the hive and half absconded,” said Motichka, who has kept bees for 15 years on a 98-acre farm that his been in his family since 1909.

Over a typical winter, Motichka said, he loses about one-third of his bees. He had never lost any volume close to 95 percent before.

“They are just not overwintering,” he said. “Anybody out there who has any ideas, I’m open-minded.”

Rising honeybee mortality accelerates attention to their plight, stirring more discussion about the reason for their demise and the potential implications for humans.

Contributors to declining bee populations include pesticides, parasitic mites, poor nutrition and disease, the U.S. Department of Agriculture and the Environmental Protection Agency concluded in a recent report.

More attention has centered since 2007 on a phenomenon called colony-collapse disorder, in which bees mysteriously fly away from hives and never return.

Some experts point to a class of pesticides made from synthetic nicotine as the main culprit, saying it interferes with honeybees’ navigational and homing instincts and causes them to vanish from hives. Neonicotinoids are a common element in agricultural seeds, including corn.

A cornfield stands about one-third of a mile south of Motichka’s farm.

As controversy over neonicotinoids’ impact on bees accelerates, the European Union recently declared a two-year trial ban on their use.

“That’s a major problem for us, the nicotine-based pesticides,” said Charles Kinbar, a Milford-area resident who has kept bees for 20 years and maintains 150 hives in Pike, Susquehanna and Wayne counties.

“I lost about 70 hives this winter,” Kinbar said. “Last year, I lost none.”

Kinbar’s bees all died in hives. His losses totaled approximately 2.5 million insects, 45 percent of his entire cluster.

“I lost $11,000 in bees,” Kinbar said. “This is the first time I ever took a big hit since I’ve been keeping bees.”

Nevertheless, he dismisses colony-collapse disorder as the sole offender.

“Anybody who says this is the smoking gun, it’s baloney,” he said. “Nobody knows.”

What is known is the importance of honeybees to human food consumption. Bee pollination contributes at least $20 billion in U.S. crop value annually, and they play a part in the production of about one-third of the nation’s food and beverage supply, according to the EPA.

In Pennsylvania, honeybees factor into more than $80 million each year in fruit and vegetable production, according to Penn State University. About two-thirds of the value is generated by the state’s apple crop.

Paul Brace, who operates a 140-acre orchard in Franklin Township, has about 100 hives to pollinate his orchard and produce honey.

“All I know is colony collapse disorder didn’t affect us. We’ve never had that happen,” said Brace, who sells his tree fruit and honey at the Scranton Cooperative Farmers Market. “We are one of the fortunate ones.”

Mortality in managed honeybee colonies over the winter averaged 31 percent nationally, according to the USDA, up from 22 percent the preceding year.

“The numbers can be a little misleading sometimes,” said Karen Roccasecca, state apiarist at the Department of Agriculture.

If a hobbyist with four hives loses two, that’s 50 percent lost, Roccasecca said. For commercial beekeepers, large bee die-offs can be crushing.

“It’s hard to sustain that level of loss, especially if that is your livelihood,” she said.

Perry Apiary in Dallas is a wholesale honey producer - the Lancaster-based family-owned firm Dutch Gold is a customer - with approximately 3,000 hives.

Owner William Perry believes he is fortunate not to have a problem with colony collapse disorder, and cold isn’t an issue: His bees winter in Florida each year.

“Maybe that’s how we’ve avoided some of the problems,” Perry said. “It’s a little bit tricky to get them through the winter up there.”

His bees mainly produce honey, although he does some pollination for a watermelon grower in Florida.

Pollination “is fairly hard on them,” he said. “It weakens the bees quite a bit.”

Some unofficial honeybee loss assessments in Pennsylvania from the winter are larger than the national average, with estimates in the 40 percent range.

“I did expect to see higher levels” than the U.S. average, said Maryann Frazier, a beekeeping expert at Penn State Cooperative Extension.

“You do hear these horror stories of people who have lost 80 or 90 percent of their bees.”

Frazier said some beekeepers have reported little or no loss, but the condition of existing bee populations causes concern.

“What we don’t have is a measure of how those bees are doing that are surviving,” she said.

Frazier said she has participated in research revealing an average of six pesticides in pollen samples from beehives. Some samples have no pesticides, she said, and others have 30.

There are implications for food production and possibly human health from the decimation of bee populations, she said.

“I’m far more worried about pesticides in general and the concentration of pesticides in hives,” Frazier said.

The depleted numbers of managed honeybee colonies drives up prices for their use.

Greg Heller rented 16 hives recently to pollinate his 50-acre orchard in Wapwallopen, paying about $85 per colony for the service. Five years ago, he paid $65 per hive.

“Every year, it’s been going up,” said Heller, who also sells fruit at the Scranton farmers market.

Kathleen Swepston of Dallas, a hobbyist beekeeper, blames the weather; her bees had plenty of honey to sustain them through the winter.

“I lost a lot of bees this year after we had a cold snap,” she said.

Swepston said the year before last, all 12 of her hives came through the winter, but last year only three of her 14 hives made it.

“When you open the hive in the spring to see what’s going on, they’re clustered together, dead,” Swepston said.

She does plan to rebuild her hives, but notes that “Bees aren’t cheap.”

“It can be an expensive hobby,” she said.

Bee replacement costs are steeper this year and there are delays in the supply because of soaring demand.

Motichka recently paid about $80 each for six packages of replacement bees. The same packages cost about $50 five years ago, he said.

“Beekeepers have been put off and put off and put off” when ordering replacements this year, Frazier said. “It’s been very hard on them. They are kind of at the end of their resources and at the end of their rope.”

Motichka, though, says he plans to continue keeping bees.

He has spent most of his life around honeybees. His father, Francis, kept bees for more than 60 years and founded the Wayne County Beekeepers Association. His sister, Dolores, is vice president of the association.

So, when Motichka discovered his winter losses, it took a personal toll.

“Your heart sinks,” he said, with a pained look in his eyes. “It’s like taking part of your family.”