An unusual experiment has revealed that honeybees are attracted to and even "drugged" by caffeine in plant nectar.

Many plants produce caffeine, primarily in their leaves as a naturally bitter deterrent against plant-devouring insects, like caterpillars.

But here, lead researcher Margaret Couvillon explains how trained bees revealed their natural addiction to caffeinated nectar.

All footage courtesy Roger Schürch, Margaret Couvillon and Hasan Al Toufailia

Video producer: Victoria Gill