How Do Bees Communicate? The Waggle Dance and Pheromones

The waggle dance: a map in motion

The waggle dance is the best-known example of symbolic communication in any animal other than humans. A forager of the western honey bee returning from a rich patch of flowers climbs onto the vertical comb and runs a figure-of-eight. In the straight middle part, the waggle run, she shakes her abdomen from side to side while buzzing her wings. She then loops back, alternately to the right and to the left, and repeats the run, sometimes dozens of times.

Other bees crowd behind her, following her movements with their antennae. After several circuits, they fly out and search for the spot.

How bees code direction and distance

The dance contains two key pieces of information:

If the waggle run points straight up, the food lies toward the sun; if it points 40 degrees to the right of vertical, the food is 40 degrees to the right of the sun. Bees correct for the sun’s movement over the day, and they can use the pattern of polarized light in blue sky when the sun is hidden behind clouds.

Distance is measured by how much of the landscape streams past the bee’s eyes during the flight, not by energy spent. Experiments in which bees flew through narrow patterned tunnels made them “overestimate” short trips. Roughly, each second of waggling stands for about 1 km (0.6 mi) of flight, but the scale varies between colonies and subspecies.

The round dance and other bee dances

For food close to the hive, within roughly 50–100 m (160–330 ft), bees perform a round dance, circling back and forth without a clear waggle run. Many researchers now see the round dance and waggle dance as one continuous system: as distance increases, the dance gradually gains a longer and more directional waggle portion.

Honey bees have several other signals:

• Tremble dance: a forager who has to wait a long time to unload nectar shakes slowly around the comb, recruiting more bees to receive and process nectar.
• Stop signal: a short vibrating head-butt that discourages dancers, for example those advertising a crowded or dangerous food source.
• Shaking signal: a bee grips another and shakes her body up and down, which tends to raise the activity of the bee being shaken.
• Piping: sounds made by queens before they emerge or fight, and by scout bees signaling a swarm to warm up for take-off; see why bees swarm.

Proof that the dance works

Karl von Frisch decoded the dance in the 1940s by training bees to feeding dishes placed at different directions and distances. He shared the 1973 Nobel Prize in Physiology or Medicine. In the 1960s, some researchers argued that recruits found the food by smell alone, and the debate lasted years.

Later experiments settled it. In 2005, a team led by Joe Riley used harmonic radar to track individual bees after they followed a dance, and showed that they flew straight toward the direction and distance coded in it, then searched around the end point. Experiments with a robotic bee have also recruited real bees to chosen spots.

Pheromones: the chemical language of the hive

Honey bees rely on pheromones, chemical signals that trigger a response in other bees, for nearly everything they do:

• Queen pheromone: a blend from the queen’s jaw glands that tells workers she is present and healthy, keeps them from raising new queens and suppresses their ovaries. It spreads through the colony as workers lick and touch her; see what a queen bee does.
• Nasonov pheromone: workers raise their abdomens at the hive entrance and fan their wings to release a lemony scent that guides lost bees and swarms home.
• Alarm pheromone: released from the sting area, it smells a little like bananas and calls guards to defend the hive.
• Brood pheromones: larvae release scents that tell workers to feed them and cap their cells, and they influence when young workers start foraging.

Touch, taste and food sharing

Bees constantly exchange food mouth to mouth, a behavior called trophallaxis. This spreads nectar and pheromones through the colony and gives each bee a constant sample of what is coming in. A forager learns that the colony needs nectar when receiver bees take her load quickly. Antennae touch everything, reading the waxy scent markings that identify nestmates, and guards at the entrance sniff each arriving bee to keep strangers out.

How other bees communicate

Dancing is unique to honey bees. The buff-tailed bumblebee and other bumblebees cannot show nestmates where flowers are; a successful forager runs excitedly around the nest and releases a scent that stirs others to search, and they learn the flower scent from the nectar she brings. Some tropical stingless bees lay scent trails from the nest to good flowers, and bumblebees and some solitary bees mark flowers they have just emptied with a scent that tells others to skip them.