The buzzing sound is produced by the rapid, high-frequency vibration of a small organism’s body parts. This noise is a byproduct of kinetic energy being transferred to the surrounding air, creating pressure waves that our ears interpret as a continuous hum or whine. The sound is common among small, fast-moving animals, where the speed of motion exceeds the frequency response of human hearing. Understanding this noise requires looking at the specific animals that generate this rapid mechanical action and the underlying physical principles involved.
Identifying the Main Offenders
The most common sources of buzzing sounds are flying insects, primarily members of the Hymenoptera (bees and wasps) and Diptera (flies and mosquitoes). Honeybees and bumblebees produce a distinct, deeper hum due to their larger size and lower wingbeat frequency. A honeybee beats its wings around 230 times per second, displacing a substantial volume of air.
Flies, including common houseflies and blowflies, also generate a noticeable buzz, often with a slightly higher pitch than many bees. Different species of flies can be distinguished by their sound. For example, one study found that the mean wingbeat frequency for some carrion flies ranged from 169 to 224 cycles per second. The size of the insect generally correlates inversely with the frequency, meaning larger flies tend to produce lower-pitched buzzes than smaller ones.
Mosquitoes are known for their irritating, high-pitched whine that can be detected easily. Their smaller size necessitates extremely high wingbeat frequencies to maintain flight, often ranging between 250 and 700 cycles per second. The precise frequency of this whine can even differ between sexes, serving as a form of communication between males and females.
The Physics of Flight Sounds
The buzzing sound is a result of aerodynamics and the physics of moving air. When an animal flaps its wings, the rapid oscillation displaces air, generating pressure waves that radiate outward as sound. The primary factor determining the pitch of the buzz is the wingbeat frequency, which is the number of times the wings flap per second.
A higher wingbeat frequency creates a higher-pitched sound, while a lower frequency results in a deeper hum. Tiny insects like midges, which may flap their wings over 1000 times per second, produce an extremely high-pitched whine. Conversely, larger moths with slower wingbeats (5 to 8 cycles per second) are often silent to the human ear. The wing’s shape and its interaction with the air during both the downstroke and upstroke also contribute to the unique acoustic signature of each species.
The sound is not exclusive to insects; hummingbirds are a notable non-insect example whose common name is derived from their wing sounds. They can achieve wing-flapping rates of up to 99 beats per second while hovering, generating an audible hum. This sound is an incidental byproduct of the rapid movement required to sustain their specialized flight pattern, similar to the phenomenon observed in insects.
Buzzing for Reasons Other Than Flight
While flight is the most common cause of buzzing, some animals intentionally produce vibrations for specific behavioral purposes. Bees, particularly bumblebees and solitary bees, use a specialized technique called sonication or buzz pollination. During this process, the bee grabs a flower and vibrates its thoracic flight muscles without moving its wings, causing the flower to shake.
This deliberate, high-frequency vibration (often several hundred cycles per second) is used to forcefully dislodge pollen from specialized anthers, such as those found on tomato or blueberry plants. This targeted action is distinct from general flight and is an effective way for the bee to collect nutrient-rich pollen. Honeybees are incapable of performing this type of intentional buzzing.
In other cases, buzzing serves as a form of communication or defense, classified as a non-flight buzz. A threatened bee or wasp may generate a warning buzz by vibrating its flight muscles while remaining stationary to deter a threat. These defense buzzes differ in frequency and amplitude from flight sounds, acting as an acoustic signal.