Why Do Bees Hum?

Why Do Bees Hum?
Sound production in bees is caused by the rapid beating of their wings. When someone approaches a hive, the bees detect the intruder by chemical scents. Other activities which are visual cues will cause bees to become aware of an intruder. Standing in the "flight-path" to and from the hive will disrupt the bee's normal activities of leaving and returning to the hive. Dark colors also seem to bother bees, and they are much more likely to investigate or become alarmed.
The increased buzzing heard from a disturbed hive is actually caused by the increased wing beat activity as the bees fan alarm phermone throughout the hive. At first approach to the hive entrance, a line of guard bees are seen which patrol the entryway and only allow hive members to enter. When an intruder or disturbance is detected, the guard bees point their stingers in the direction of the intruder and open the plates that overlap to cover the abdomen, all the time furiously fanning their wings. Under the last segment of the abdomen lies the scent gland which produces the alarm phermone, a chemical scent that communicates danger to the hive. As the alarm scent is spread throughout the hive, more bees release alarm scent and begin to fan until the characteristic "buzzing" sound of an upset hive become audible.

The alarm scent both communicates danger to the hive and stimulates bees to take flight in defense of the colony. The degree to which this alarm and buzzing occurs is realted to the size of the hive. Single field bees seldom emit much sound since they are unlikely to defend a single flower in the way thousands of bees will defend a hive.

Other Bee Sounds

"Queen piping" refers to an audible squeek emited by queen bees under special circumstances. The sound is made by vibrating the folded wings. It is believed that the vibrations of small plates at the base of the wings produces the sound since queens that have had their wings clipped can still pipe. The queen may also rest her body against a hard surface and use it as a sounding board.

Queen piping is associated with swarming activity. One study discovered that in the 25 minutes before the colony swarmed, the queen piped 25 times. Piping seems to take place between the queen ready to leave with the swarm, and the developing queens still in capped cells. The queen's piping may serve as a warning for new queens to delay emergence until the swarming queen has left.


Dance Communication

When field bees return to the hive, they perform a "waggle-dance" which communicates the type and location of a food source. During the dance, a worker will sometimes emit a short "weep" sound which will cause the dancer to stop and offer the pollen or food to the requesting worker.

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Last modified 20 November 1998