It's been three years since the first reports emerged of what some scientists call colony collapse disorder: the sudden wasting away of previously healthy beehives. Researchers have been largely at a loss to explain the situation, which has now spread through the North America, Europe and parts of Asia. Some point toward disease and pesticides, while others put the blame on the way hives are being handled by commercial beekeepers.

It's all the same to David Bradshaw, a California commercial beekeeper who says his methods are no different than those employed by his father. Bradshaw purchased the family bee service 12 years ago. He tells the BBC that at one time, he had some 4,200 hives to rent out — mostly to the almond industry, which depends on commercial honeybees to pollinate their crops. Today, he's down to just over a quarter of that number. And the hives continue to die.

Brett Addee is another California beekeeper. He's an even bigger operator — his company is the largest in the United States — but the story is the same. More than a third of his bees have simply disappeared. The Guardian caught up with Addee as he surveyed his struggling hives:

While scientists continue to debate ways to address colony collapse disorder, commercial honeybees aren't the only pollinators. Natural bees also play a part, and there are things we can all do to improve their habitat and keep wild bee populations healthy. Check out five ways to help our disappearing bees and do your part. That buzzing in your yard this spring is good news for bees — and everyone who depends on them.

Beekeepers say their hives are still in trouble
The cause of colony collapse disorder remains uncertain and that's bad news for farmers and the rest of us.