A mysterious problem that causes bee colonies to decline is once again taking its toll on California's beekeepers.

The problem known as colony collapse disorder is characterized by a sudden drop in a bee colony's population and the inexplicable absence of dead bees.

The disorder has no known cure and appears to be cyclical. After several mild years, it has resurfaced with a vengeance, said Eric Mussen, apiculturist with the University of California at Davis.

"It never went away, but this year a substantial number of beekeepers got walloped again," said Mussen, the state's leading bee expert. "And worse than they had been hit before."

Although Mussen said it is too early to tell exactly how many bees have been lost, a bee industry official said losses in the state vary from 30 percent to 80 percent.

Roger Everett, a Tulare County beekeeper and president of the California State Beekeepers Association, lost 50 percent of his nearly 6,000 bee colonies.

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