The busy bee may be a cliche. But it turns out that bees are very busy on the world’s farms, pollinating many of the fruits, vegetables and nuts we eat.

But a major report from the National Academies says bees and other important pollinators are losing out to development and disease. The report’s authors warn the losses could have a big impact on some farmers, such as the almond growers of Central California.

Growers there depend on commercial beekeepers to produce their billion-pound nut crop, which is among the state’s most valuable agricultural product.

Beekeeper Gene Brandi stores some of colonies in large white boxes not far from a sprawling almond orchard near Los Banos.

Last spring, his bees spread pollen from tree to tree in the orchard. Now, giant harvesting machines are moving through the orchard, shaking trees with a crab-like craw and making the nuts spill down to the ground.

Recently, Brandi was getting his hives ready for the winter. He wore a big round hat with mesh that kept the honeybees off his face. To keep the bees calm, he shot puffs of dark gray smoke into the hives, after dropping matches into a beat-up metal box called a smoker. “The smoker is the beekeeper’s best friend, other than the bees themselves,” he said.

Brandi’s been a beekeeper since 1978. In that time, his bees have pollinated not just almond trees, but cranberries, blueberries, cherries, apples, plums, melons, avocados and wide variety of vegetables. According to the new report, beekeepers like Brandi help put the bloom on at least 90 important crops — including about one-third of the fruit, vegetables and nuts found in your local store.

Indeed, many beekeepers ship their bees around the country so that they can be in the right place at the right time for the farmers.

Brandi says it takes a lot of healthy honeybees to do this massive job — like the ones in his colonies.

“Big full bodies, full wings,” he says, admiring his bees. “They are gathering nectar, gathering pollen, and that indicates colony health to me. These are basically happy contented bees.”

But keeping bees healthy isn’t easy, he says. You have to watch out for everything from freakish weather to predators like bears and skunks. Brandi says the skunks come in at night and scratch at the front of the wooden hives.

“And they get the bees to come out, and they will fill their bellies with bees,” Brandi says. “They don’t want honey they just want bees,” he says.

But Brandi says bears and skunks are nothing compared to a newer threat. It’s a tiny Asian mite that sucks the juices out of European honeybees, crippling and then wiping out entire colonies.

Scientists know this mite as the Varroa destructor. Beekeepers call it the vampire mite.

According to the new report, the vampire mite helped wipe out the nation’s wild honeybees in the late 1990s. Then it started ravaging commercial colonies. Brandi, who owns 2,000 hives, says his bees got hit hard in the winter of 2004. He remembers pulling the lids of boxes and hearing silence.

“I ended up with a 30 percent loss,” he says, one of his biggest ever.

It is hard to understate the damage these mites are doing to the nation’s most important pollinators. Researchers say they have helped reduce bee numbers by nearly 30 percent over the last 25 years.

As a result, even as almond farmers and others need more pollinators, there are far fewer European bees to go around. And some experts, like Eric Mussen of the University of California, Davis, worry that the vampire mites could be everywhere again this winter.

“This year is another one of those years where the bees are not particularly strong and healthy,” Mussen says.

“Unfortunately, I am afraid that we are looking forward to another winter of significant winter losses and fewer bees next spring.”

Mussen says he worries that the mite attacks will help put a lot of beekeepers out of business. That could further accelerate a long-term decline in the number of commercial beekeepers. These are jobs people have to want to do, he says.

“You get up before dawn and work until long after dark, and then you get up and do it again the next day,” Mussen says.

Experts say it’s possible that other bee species could take the place of some of these commercial bees. Robbin Thorp, an emeritus professor at UC Davis, has been studying and collecting native bees for more than 40 years now. He shows off several thousand specimens lined up in the long glass drawers inside a compact museum at the university.

Thorp turns a crank that opens up a row, and finds one kind of bee that could be helpful.

“That’s Bob,” Thorp says. “The blue orchard bee. It’s being used to pollinate apples and cherries.”

There are other wild bees that could pollinate crops, he says. Unfortunately, many of these kinds of bees may also be in decline, according to the new report. And, ironically, the farms that need bees the most are a big part of problem. Giant weed-free farms that destroy habitat and use a lot of pesticides are the worst offenders, Thorp says, and have helped drive some bees to edge of extinction.

There are solutions to these problems. For instance, efforts to restore habitat that might support wild bees are now underway. And researchers also are looking for ways to kill the mites.

The question now is whether those new programs will pay off in time to help avert a looming pollination crisis. It’s a crisis that might begin with the news that there are not enough commercial bees to pollinate California’s ever bigger almond orchards.

A symbol of this potential crisis now passes by the UC Davis campus every fall, when large numbers of commercial honeybees migrate into California for the mild winters. The trick is that these bees don’t fly west on their own wings, but travel inside the wooden boxes piled up in tractor-trailers rumbling down the interstate freeways.

Unofficially it’s the biggest insect migration in the country.