It started in 2006. Scores of honeybees began dying for seemingly no reason, prompting scientists to come up with the term "colony collapse disorder." According to the Department of Agriculture, reported bee-colony death rates in the U.S. were 29% in 2009, rising to 34% in 2010. And although a handful of plausible explanations have been offered — fungal infection, pesticides, climate change — no one really knows why they're dying. But it's not just honeybees: a recent study by the University of Illinois suggests that the four main types of bumblebee populations have plummeted more than 90% in the past 20 years.