Since August, bees in the town of Ribeauville have been feasting on "unidentified colourful substances", causing their honey to turn shades of green, blue and purple.
The colourful contaminants come from a nearby factory that has been processing M&M's candy waste.
While the substance tastes like honey, beekeepers have had to dispose of the concoction.
The processing plant has since cleared its containers and says it will be storing future waste indoors, far away from hungry bees.
This is the latest round of setbacks for local beekeepers, who have been struggling to turn a profit amid dwindling bee populations and limited honey supplies caused by a harsh winter.
With files from Reuters