DADE CITY - To a veteran beekeeper like David Hackenberg, it was as astonishing as seeing water flow uphill.

Last October, he left 400 hives in a field in Ruskin to feed in Brazilian pepper tree blossoms. When he returned a month later, all but 36 of the colonies had been abandoned, right down to the part of the honeycomb filled with larvae and pupae - the future of the hives.

"I could tell the whole order of things had just gone haywire," said Hackenberg, 58, who has been keeping bees since he was 12.

Hackenberg, who spread the word to scientists and other beekeepers, is credited with sounding the alarm about what may be the most devastating honeybee die-off in U.S. history.

The crisis, marked by bees mysteriously vanishing from their hives, has been identified in 24 states in every part of the country, said Jerry Hayes, Florida's chief apiary inspector; about 35 percent of Florida's colonies have disappeared, he said, with the losses concentrated in the southern half of the state, where many beekeepers from the eastern United States spend the winter.

Unless scientists can find the cause of the die-off and a solution, its long-term consequences may be as ominous as its name: Colony Collapse Disorder.

Not only are the livelihoods of beekeepers endangered, Hayes said, but so is the estimated one-third of the nation's food supply that depends upon honeybee pollination - apples, almonds, melons, blueberries and some varieties of citrus, including grapefruit.

"Honey is a byproduct of pollination," he said. "It's wonderful and it's great, but more importantly, without honeybees taking pollen from one flower to another, that plant has no reason to build a fruit or a nut."

Scientists alerted

Even so, beekeeping remains a small and underappreciated industry, Hackenberg said, "the ugly stepchild of agriculture."

That is why Hackenberg has been so important, Hayes said. He is well-connected, opinionated, funny and, for an interview on Thursday afternoon, dressed to stand out, wearing a multicolored hat advertising his business, and a large, square belt-buckle engraved with images of bees and honeycomb.

A former president of the American Beekeeping Federation, he has been on the telephone constantly in recent weeks, talking to reporters across the country from his winter headquarters in a remote corner of northwestern Pasco County.

When he began telling fellow beekeepers of his vanishing hives last fall, some were skeptical, but others told him they had been losing large numbers of bees for more than a year.

By reporting this to agriculture officials, Hayes said, Hackenberg "was the one who got this whole thing started."

In response, farming experts from several states and universities have formed an emergency working group to study the disease.

So far, the scientists know only two things for sure, said Dennis vanEnglesdorp, Pennsylvania's state apiarist: The main symptom has been the mass abandonment of hives. And the variety of fungi, viruses and mites found in collapsing hives suggests a widespread failure of the bees' immune systems.

"It's a lot like AIDS," Hackenberg said.

The rest, at this point, is conjecture.

Bees are increasingly trucked long distances to take advantage of crops, such as almonds, that pay high pollination fees. This may strain their ability to recover from infections, the report says, and expose them to a wider range of diseases and toxic chemicals.

"They forage over a large area so they pick up a lot of junk," Hayes said.

The "prime suspect" for the collapse, according to Hackenberg, is an increasingly popular class of pesticides called neonicotinoids that the U.S. Environmental Protection Agency has identified as highly toxic to honeybees.

Another possible culprit, vanEnglesdorp said, is a new strain of fungus that has appeared in many of the failing hives. But he and Hayes warned it is far too early to settle on a single cause of the outbreak.

Beekeepers have reported several smaller but equally mysterious collapses in the past, vanEnglesdorp said. In the 1980s, invasive mites from South American all but wiped out the feral bee population and contributed to a steep decline in U.S. beekeeping. The number of hives in Florida has since dropped from a peak of 12,000 to about 1,000 currently, Hayes said, and the number of colonies from nearly 400,000 to 279,000.

That, at least, was the count before the current collapse, which cost Hackenberg about 2,000 of his 3,000 hives - and an estimated $350,000 in lost revenue and the expense of rebuilding his stock of colonies.

By "splitting" hives, taking bees from a healthy colony to a new box with a young queen, Hackenberg has already created 400 hives. He has deposited some of these into nearby orange groves, where they will improve the harvest, produce a premium grade of honey and use the nectar to build "good, strong, boiling-over beehives that we can take up North to pollinate apples."

So, he is confident his business will survive this year, he said. "But what's going to happen next year, if whatever is causing this is still out there? What's to say the problem is not going to get bigger?"