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