It's Mysterious indeed. How can a bee keeper who had 2900 colonies of bees suddenly lose 1900 colonies without warning? It's called called Colony Collapse Disorder and it's running ramped while experts are trying to find the reason behind it! Bees that have been studied were found to have foreign fungi, bacteria and other organisms that are weakening the bees immune system. The problem has spread over 24 states and can become or already is a very serious problem. For instance, in Florida, the sate's 45 million dollar apple crop is 90 percent dependent on the bees pollination! The problem is so bad that I heard on the radio today that congress will be looking at the problem. Hopefully this can be resolved sooner than later.
Some resources to investigate:
Also Google Colony Collapse Disorder.