America's honeybees are dying off at a fast rate because of a mysterious killer called Colony Collapse Disorder. 

In the past seven years since it was first reported, about a third of America's honeybees have died off. 

Those bees are needed to pollinate all sorts of crops we eat, like pumpkins, almonds, and apples. 

Without these pollinators, farmers could lose $15 billion in crops. 

But some experts are proposing an unusual solution: using lesser-known bee species and training them to do the job.

More people know about honeybees -- which are actually European transplants -- and bumblebees. But America is home to thousands of native bee species. Most of their habitat, however, was destroyed when humans began transforming the natural landscape for the purpose of large-scale farming.

In a piece for Scientific American magazine, contributor Hillary Rosner explains how scientists in California are figuring out ways to encourage native bee species to return, and lighten the pollinating load for honeybees.