Certain plants, to reproduce, require a menage a trois with a bee.

Increasingly, bees aren't showing up.

David Hackenberg has never seen anything like it in a half century of beekeeping.

Hackenberg, 63, grew up on a dairy farm in Pennsylvania and has relished the aromas of honeybees gathering fresh nectar from an early age.

"It's plant sex," he said. "Without it...there are no apples, blueberries, watermelons, almonds or pumpkins."

Today, his Lewisburg, Pa.-based company, Hackenberg Apiaries, provides bees to fruit, nut and vegetable growers in California, Florida, Georgia, Maine, Michigan, and Pennsylvania.

He runs up to 3,000 hives with 30,000 to 40,000 bees apiece. But it is all he can do to keep them from disappearing like tiny planes in the Bermuda Triangle. Hives, buzzing like cities, can go mysteriously vacant.

There are no signs of bee struggle. There are no dead bee bodies. The bees are simply gone. It is like a bee rapture with no bejesus.

Some blame cellphones, global warming or genetically modified crops. Others pin the phenomena on alien abductions. "I've heard it blamed on "The Russians,'" Hackenberg said.

Scientists still remain puzzled over what they call Colony Collapse Disorder, attributing it to multiple possible factors. But Hackenberg is pretty sure he knows what's causing it.

In Jerry Seinfeld's 2007 animated "Bee Movie," bees file a lawsuit against humans to redress over-consumption of honey. Flowering plants--and many sources of food--die out. And a cartoon humanitarian crisis ensues.

Hackenberg is featured in another bee movie, an award-winning documentary called "Vanishing of the Bees," narrated by actress Ellen Page of "Juno" (2007) and "Inception" (2010).

The independent film, which has already made the rounds in Europe, is now screening across the U.S. through at least the beginning of June as part of the "Do Something Reel Film Festival," presented by Whole Foods Market. (Find a local screening at www.vanishingbees.com.)

Filmmaker George Langworthy told me he landed Page as the film's celebrity narrator through Leonardo DiCaprio. During production of "Inception," DiCaprio and Page were having a snack.

"One of the assistant directors killed a bee that was hovering around the table," Langworthy said, "and she kind of chewed him out and said, 'You shouldn't kill the bees. Don't you know there's a crisis with bee health?' Leonardo was standing there and said 'Wow, you should see this film.' And it was right at the same time we were looking for a U.S. narrator."

Hackenberg has never met Page and isn't caught up in being one of her co-stars, or being on CBS' "60 minutes," or even becoming the face of the bee crisis.

"I'm just hoping the message that's in this movie gets out, and people start thinking about where their food comes from," he said.

Hackenberg blames neonicotinoids, a modern class of insecticides, and its leading manufacturer, Bayer AG (BAYRY).

"He is selling this, but he has nothing to back to it up," said Jack Boyne, a spokesman for Bayer CropScience LP in Research Triangle Park, N.C.

Boyne, who has a doctorate in entomology, said Bayer officials have had long discussions with Hackenberg and other beekeepers.

Boyne ran though a litany of studies showing no causal relationship between neonicotinoids and colony collapse disorder. U.S. farmers have been using neonicotinoids since 1994, and the mysterious bee disappearances weren't widely noticed until 2007, Boyne said.

Bayer, which depends on bees to pollinate its own canola seed production in Canada, wants the problem solved too, Boyne said. One possible contributor, he said, is the rise of the parasitic verroa mite.

"We are obviously sympathetic to the plight of the beekeeper and this malady facing the bees," he said. "I know these beekeepers are frustrated."

Bayer officials met with filmmakers but refused to appear on camera. "They were looking for a villain," Boyne explained.

Mostly, what Hackenberg points out is an intriguing correlation. For many years, scientifically unsophisticated people correlated polio and ice cream. But also for many years, scientifically unsophisticated people correlated cancer and smoking. Big tobacco insisted this was ridiculous, but was it really?

The truth sure gets complicated when business is at stake.

"The technology in this whole thing is so well buried," Hackenberg said. "These huge companies are good at hiding their trade secrets."

And the bees keep vanishing. Where do they go? "Nobody knows," Hackenberg said. He suspects they fly off to die in the brush, their little bodies never to be recovered.

"I don't worry bees are going extinct," Hackenberg said. "I'm more worried about commercial beekeepers going extinct."

(Al's Emporium, written by Dow Jones Newswires columnist Al Lewis, offers commentary and analysis on a wide range of business subjects through an unconventional perspective. Contact Al at al.lewis@dowjones.com or tellittoal.com)