A Robot with the Right
Bee-havior

By Gary Raham • Illustrated by John Rice

At first, the real honeybees did not notice the robot bee in their hive. But once the robot began to beat its metal wings, a few nearby bees turned to face it. The metal bee danced. The real bees left the hive and went directly to a pan of sugar water that scientists had placed nearby. The robot was speaking “honeybee language.”

This tiny robot bee is helping to solve an old mystery: How do bees tell their hive mates where to find the flowers with the richest and tastiest nectar? For years, careful observers could see that bees communicate, but it took a long time for someone to learn how they do it.

The Waggle Dance
After finding a rich source of food, an explorer bee returns to the hive and dances in a special way on the wall of the hive. In the 1940s a German scientist named Karl von Frisch studied the honeybees’ dancing and concluded that the movements were a kind of language.

When a honeybee finds food for her hive, she has some of the same problems that people have when they give directions to an unfamiliar place. (The bees that explore for food are always female, and so are the bees that collect it.) The bee must tell her sisters which way to fly and how far they will have to go. Von Frisch also suspected that she told something about the quality and quantity of the nectar. But how does the explorer bee talk to her nest mates in a dark hive?

The mystery has to do with a dance that the explorer bee does on the hive wall called a “waggle dance.” The bee moves in the pattern of a double loop, like a figure eight. She waggles her backside between one loop and the next.

Other bees come over to check things out. The returning bee is somehow “recruiting” them to gather the food she has found. Then, the recruited bees go out and find the new food without any more help.

A Dance Language
Von Frisch tried to understand the bees’ dances. He watched honeybees in a special hive with a glass wall. He found out where the bees went after each dance. Then he figured out which part of the dance told the other bees which way to go and which part told how far to go.

Von Frisch discovered that the direction the bee faced when it waggled told the other bees which way to fly to find the flowers. If the explorer waggled while she faced straight up the honeycomb, the others flew toward the sun to find the flowers. If the dancer waggled when she faced straight down the comb, the others flew away from the sun. If the bee waggled while facing sideways to the right, the others went to the right of the sun, and so on.

Von Frisch also noticed that the speed of the dance matched how far away the food was. The faster a worker “looped and waggled,” the closer the flowers.
Many scientists thought von Frisch was right. But others had doubts. They were not sure how an explorer bee could get the attention of the other bees in
the dark.

Scientists tried to test von Frisch’s ideas by building robot bees that could dance in the honeybee’s language. But the real honeybees paid no attention to the robots.
Two researchers, Wolfgang Kirchner and Axel Michelson, tried something different. They knew that other researchers had discovered that honeybees can make some sounds with their wings at a lower pitch than their familiar buzzing sound.

Most scientists thought that bees could not hear and that these sounds were not important. But Michelson and Kirchner discovered that honeybees can hear. Like some other insects, honeybees have hearing organs on their antennae.

These “ears” might explain how honeybees can get important information from an explorer bee's dance in the dark. The honeybees might not be able to see which way she faces when she waggles, but they can probably tell by listening.
Kirchner and Michelson wanted to find out whether the dancing bee beats her wings to say, “Listen. I can tell you where to find lunch.”

Metal Bee
They made a robot body out of brass and gave it metal “wings” that vibrated at the same speed as honeybee wings. A motor controlled the robot’s figure eights and waggles. A thin plastic tube delivered a sample of sugar water for other bees to taste. (Real explorer bees give out samples.) This new robot worked. It got the honeybees’ attention, and it told them how to find a pan of sugar water lying in a field.

Now scientists are listening in to learn what other kinds of bees have to say. Of the four species of honeybees studied so far, all have some variation of the dance language. Three species that live in dark hives get their nest mates’ attention with sound. The fourth species, a dwarf bee, dances silently in the daylight. Do some bees use sound to communicate other kinds of information? Someday we may find out.