Flowers Have Hidden Heat Signals That Attract Pollinating Bees

(From left to right) The heat patterns of poppy, rockrose, and daisy flowers.

(From left to right) The heat patterns of poppy, rockrose, and daisy flowers. University of Bristol

It is well understood how flowers use complex color patterns and smells to attract pollinating bees. But now, scientists have discovered that flowers also emit heat to advertise themselves to insects — creating temperature arrays that mimic the color designs of petals.

On average, heat spots were 4 to 5 degrees Celsius warmer than the rest of the flower, but could be as much as 11 degrees warmer.

To test how significant these heat signatures are in insects’ pollinating behaviors, scientists from the University of Bristol in the United Kingdom created artificial flowers that only had temperature patterns, not colors or smells. They found that bumblebees were able to use the patterns — invisible to the human eye — to distinguish between different flower species and the pollen they provided. They published the research earlier this month in the journal eLife.

“The presence of multiple cues on flowers is known to enhance the ability of bees to forage efficiently,” said Heather Whitney, a biologist with the University of Bristol and lead author of the new study. But she warned that climate change could have “additional previously unexpected impacts on bee-flower interactions by disrupting these hidden heat patterns.”