Video: Beekeepers solve mystery of blue honey

Beekeepers were initially stumped as to why this was happening, but now believe reason is the bees’ fondness for M&Ms.

The Alsace apiary where the strangely-coloured honey was appearing is very close to a biogas plant which deals with waste from a Mars chocolate factory, reports the BBC.

It is thought the bees have been munching the sugary waste from M&Ms, and the colouring has contaminated the honey they produce.

This summer’s heavy rain meant that bees have not been able to forage as much, said a spokeswoman for the British Beekeepers' Association, Gill Maclesn

"Bees are clever enough to know where the best sources of sugar are, if there are no others available," she said.

The plant operator said it regretted the situation and had put in place a procedure to stop it happening again. As for the blue honey, the beekeepers say it is unsellable.