Originally scientist thought that bees made a buzzing sound with the rapid beats of their wings, which were though to course air vibrations that the human ear detected as a buzz.  Larger bees had slower wing beats, which were thought to cause the lower buzz pitch, and smaller bees that had higher wing beats also had higher pitched buzzes.

However this did not explain why some bees could buzz whilst completely at rest, and so scientists were forced to look deeper for answers.  It has now been discovered that it is not the wing beat that actually causes the buzzing noise, but instead it is all part of the complex flight system found in bees and flies known as the ‘click mechanism’.  This mechanism is what allows the bees to flap their wings fast enough to provide enough thrust and lift to fly their relatively heavy bodies.

The buzzing noise is created as the bees thorax clicks in and out of place at high speed, which enables them to not only flap their wings, but also to twist and turn them at an angle as they beat up and down, which reduces drag and allows the bee to beat their wings even faster.  This means that they can get as many two beats or more for every tiny muscular contraction, which equates to as many as 200 beats per second.  The click of the exoskeleton resonates in the thoracic cavity and creates that characteristic buzzing sound.

Scientist also think some bees, such as the larger bumble bees, also use this buzzing vibration to help shake pollen free from flowers, and this may explain why some bees still buzz loudly when they are on flowers, especially plants such as tomatoes and honey suckle as these have tubular anthers which are more difficult for larger bees to reach the pollen inside.

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