Grist: Bees are having a really hard time right now. For about a decade, they`ve been dying off at an unprecedented rate - up to 30 percent per year, with a total loss of domesticated honeybee hives in the United States worth an estimated $2 billion. At first, no one knew why. But as my colleague Tom Philpott has reported extensively, in the last few years scientists have accumulated a compelling pile of evidence pointing to a class of insecticides called neonicotinoids. These chemicals are widely used...