[Below is the original script. But a few changes may have been made during the recording of this audio podcast.]

Spring is in the air and as flowers bloom, honeybees buzz into action, pollinating from now until late fall. Humans add to that bee business, trucking the insects across country to pollinate vast fields of crops, from almonds in California to apples in Maine.

While this sounds like the most natural thing for the honeybees, they are technically an invasive species in North America.

That's right, the seemingly sweet honeybee is a human-introduced European import crowding out native species, such as the blue orchard bee. Not unlike zebra mussels or kudzu.

But honeybees are a useful invader. With other insects, they provide some $57 billion worth of free ecosystem services, such as pollination.

That's why scientists sprang into action as reports of a mysterious disease wiping out bee hives swarmed in 2007 and 2008. Dubbed colony collapse disorder, the deaths have been linked to pesticides, disease and overwork. For more on that, check out our online In-Depth Report this week "The Buzz on Bees."

While studies have shown that our native bees could pinch pollinate for the European imports, their populations are too small to fill the honeybee's role.

Fortunately, early reports from this winter are promising. Honeybees seem to be recovering. That's sweet news for farmers, foodies and, yes, honey lovers.

—David Biello