How Bees Find Their Way Home

A worker bee weighs about as much as a paperclip, yet it is one of the natural world''s finest navigators. A single bee can fly several kilometres from its hive to look for flowers and still get straight home afterwards, often along a more efficient route than the one it followed on the way out. How a creature with a brain the size of a grass seed manages this has puzzled scientists for more than a hundred years.

The first big clue came from Karl von Frisch, an Austrian biologist working in the 1940s. He noticed that bees coming back to the hive perform a kind of dance on the surface of the honeycomb. The direction and length of this dance tell other bees the location of a food source, sometimes hundreds of metres away. Von Frisch was awarded a Nobel Prize in 1973 for this work.

Bees, it turns out, do not rely on a single trick. They use several different cues at the same time. One is the sun: they can navigate by the position of the sun even when it is partly hidden behind clouds. They also appear to recognise landmarks such as tall trees or buildings on the ground below. A few studies hint that bees can sense the Earth''s magnetic field too, although this finding remains debated.

Why should anyone care about the travel habits of an insect? The answer is on our plates. Bees pollinate many of the crops that humans depend on, and a healthy bee population needs healthy navigation. Over the past few years, scientists have grown concerned that pesticides and habitat loss may be making it harder for bees to find their way back to the hive. If that turns out to be the case, it could affect food production around the world.