David Bradshaw's family business is threatened by colony collapse disorder
All over the world bees have been disappearing but nowhere has been more affected than the United States.
Scientists there have dubbed the phenomenon colony collapse disorder - but some experts argue that this is misleading, and that what's killing the bees is the way they are being exploited by commercial beekeepers.
BBC World Service science reporter Matt McGrath went to meet one beekeeper in California for whom colony collapse disorder is a very real affliction.
On a windy isolated dirt track, in the shadow of the Sierra Nevada mountains sit David Bradshaw's bee hives, hovering between life and death.
David scampers around the sick colonies prising off the lids and lifting out the sticky wooden frames on which the bees build their honeycombs. He doesn't like what he sees.
"There should be bees covering two thirds of the frame, that's how you measure colony strength"
He holds up the rectangular divider, a few brown shapes crawl around on the comb in the middle.
"This one's only, two frames of bees I'm hoping to find something round here to show you oh..this one's terrible, that's terrible too .they're all pretty much the same," he says with a mixture of frustration and resignation.
I've been tending to these bees and doing everything I can for them and they still die
Many of these hives are too weak to survive and the bees will soon be gone. David will then transport the empty boxes that once housed the colonies back to his yard. Already the crates there are stacked high.
52-year-old David has beekeeping in his blood. And the decimation of his hives hurts him deeply. "This is all I've done, and I take pride in my bees and it kinda tears at me, its part of me, it's what I do, I live and breathe bees."
The Bradshaws was a family business. His father, who had once worked on the Gemini rocket programme that took America's astronauts to the moon, decided that bees were a better bet than space exploration. About twelve years ago, David bought his father out.
There were some good years, thanks in the main to the rapid expansion of the almond industry that dominates this part of the central Californian valley. The almond growers depend on commercial beekeepers to pollinate their valuable crop. At one time, David had 4,200 hives out to rent.
Commercial beekeeper David Bradshaw explains what the loss of bees has meant to him
But for the past five years, the mysterious affliction that has been dubbed colony collapse disorder has devastated David's hives - He now has just 1200 left. Initially David blamed himself.
"I'm their keeper, you know if I had a herd of sheep and they got out on the road and they all got hit by a car it would definitely be my fault. But I've been tending to these bees and doing everything I can for them and they still die.
"Talking to the experts, they don't know, nobody has any help, it seems like we are all on our own .."
The scale of the losses has taken their toll on David. He says with a laugh that he's glad his wife has a good job.
"There have been quite a few sleepless nights, especially at this time of year it used to be fun .I'm still a beekeeper, I have to have bees to rent, if I don't have bees then I'm not in business."
The use of the term colony collapse disorder has been criticised by some scientists and other experts who say that it's often an excuse for poor beekeeping. David sighs heavily.
"Well I don't abuse my bees, I kinda take offence at that, when we transport them we take great pains to make sure they arrive safely, to make sure they have water. It's totally unexplained.
"That's the frustrating part. There's no reason that these bees here should be in this shape, just three months ago they were beautiful bees, they were large thriving colonies, and to have them dwindle down to one or two or frames of bees is beyond comprehension as far as I'm concerned."
But despite the disappearance of his bees, and the lack of clarity about what's causing it, David remains an optimist. He points to a small discreet emblem on the side of his pickup truck, a hieroglyph of an ancient bee.
"That little hieroglyph there is Egyptian it stands for a beekeeper or bees. It's an ancient craft; it's been around a long time. The bees will endure."
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