Bees at a cluster of apiaries in northeastern France have been producing honey in mysterious shades of blue and green, alarming their keepers who now believe residue from containers of M&M’s candy processed at a nearby biogas plant is the cause. Since August, beekeepers around the town of Ribeauville in the region of Alsace have seen bees returning to their hives carrying unidentified colorful substances that have turned their honey unnatural shades. Mystified, the beekeepers embarked on an investigation and discovered that a biogas plant 4 km (2.5 miles) away has been processing waste from a Mars plant producing M&M’s, bite-sized candies in bright red, blue, green, yellow and brown shells. Asked about the issue, Mars had no immediate comment.