What’s happening to the bees?

For several years now, third-generation beekeeper Tibor Szabo has watched large stocks of his beloved honeybees die off.

"Bees that just land around the yard, just sitting on plant leaves, running around in the grass: they're not coming home," said Szabo.

"They're twitching and spasming in front of the hive. A good percentage of the colony just disappeared."

Szabo’s plight is part of a crisis among the colonies. According to a report released this week by the federally supported Bee Informed Partnership, honeybee deaths have been above historic averages for nearly a decade — but not in any predictable way.

Bees die every winter, and the acceptable range of loss for a healthy colony hovers around 15 percent. However, in the winter of 2010–11, for example, the loss of managed honeybee colonies on average was 30 percent — well over the acceptable range.

In the following season, the death range was around 22 percent. It then rocketed back up to 31 percent in the winter of 2012–13.

This past season, losses were at 23 percent.

The U.S. Department of Agriculture has been closely monitoring hive losses since 2006, when the unexplained colony collapse disorder came to light.

Other researchers see the deaths as resulting from a range of other lethal factors such as viruses, parasites, environmental changes or pesticides.

"Eventually we're going to reach a threshold where it's not going to be worth it for a beekeeper to maintain a colony only to see 40 percent of it die every year,” said bee biologist Amro Zayed.

Bees are highly evolved socially, and they protect each other communally from diseases. Therefore, their species is more fragile, as they have less individual immunity than other insects.

"Ten years ago they seemed to be bulletproof and invulnerable to any of the diseases," said bee researcher Mike Allsop. "Now we are seeing that they are getting sick and dying."

Bees and the plants they pollinate form a symbiotic relationship that comes together on the American dinner table to the tune of 1 in 3 mouthfuls, according to the Department of Agriculture.

An estimated $15 billion in value is added to U.S. crops each year by bees.

"If we lose bees, we’re going to lose a significant amount of our food supply," said bee scientist Clement Kent.

"That’s it. Without bees, we don’t get fruits, don’t get a lot of animal feeds that are dependent on bee pollination. There are many things we’ll lose.”

What's happening to all the bees?

Can American agriculture adapt?

What do bee deaths say about the overall wellness of our ecosystem?

We consulted a panel of experts for the Inside Story.