The hottest summer months often bring a distinctive acoustic phenomenon: a loud, continuous, high-pitched buzzing that seems to emanate from the treetops. This relentless sound is a characteristic soundtrack of the season, marking the peak of warm weather. This intense, whirring drone is one of the most recognizable noises in the natural world. The sheer volume and persistence of this summer sound often leads people to wonder about the creature responsible for such a powerful chorus.
Identifying the Cicada
The insect behind the summer’s loudest, most sustained buzz is the cicada, a large and robust member of the order Hemiptera, or true bugs. They are easily recognized by their thick bodies, large, clear, membranous wings, and prominent, wide-set compound eyes. Adult cicadas typically range from one to two inches in length, and their coloration varies significantly between different types.
The most common types are annual cicadas, sometimes called dog-day cicadas, which appear in late summer and often have camouflaged bodies in black, green, or olive patterns. Periodical cicadas are famous for their synchronized mass emergences every 13 or 17 years, and these species are generally smaller with black bodies and striking red eyes. Both types spend the majority of their lives feeding underground as nymphs, but the adults emerge solely for mating, which is the purpose of their intense acoustic display.
How the Cicada Produces Sound
The unique sound produced by the cicada is not created by rubbing body parts together, as seen in crickets, but through a specialized organ found exclusively in the males. This structure is a pair of tymbal organs, which are circular, ribbed membranes located on the sides of the insect’s abdomen. The tymbal is composed of a series of stiff ribs embedded in a flexible plate of exoskeleton.
Sound production begins when a specialized, powerful muscle attached to the tymbal contracts and relaxes rapidly. This muscle action causes the ribbed membrane to buckle and unbuckle sequentially, with each buckle producing a distinct, sharp click. The muscle can contract between 120 and 480 times per second, producing individual clicks so quickly that they merge into the continuous, loud buzz heard by human ears.
The cicada achieves its astonishing volume, which can reach over 100 decibels, by employing its largely hollow abdomen as a natural resonance chamber. This large, air-filled cavity acts like the body of a drum, greatly amplifying the sound waves generated by the tymbal clicks. The male cicada can modulate the sound’s intensity and pitch by flexing muscles to open and close specialized flaps, or opercula, over the tymbal organs.
Other Common Summer Buzzing Insects
While the cicada produces the most prominent and continuous summer drone, other insects contribute to the seasonal buzzing chorus with different sounds and mechanisms. Many common buzzing noises are incidental sounds of flight, created by the rapid movement of wings through the air. Large Hymenoptera, such as bumblebees, hornets, and carpenter bees, create a lower-pitched buzz because their larger wings beat slower than smaller insects. This sound is localized, temporary, and linked to their movement, lacking the sustained nature of the cicada’s call.
Other familiar summer sounds come from insects that use stridulation, a mechanism involving rubbing two specialized body parts together. Crickets and katydids, for example, produce rhythmic chirps and clicks by scraping a file-like structure on one wing against a scraper on the other. This method results in a pulsed, rhythmic sound, often heard at night, which is clearly distinguishable from the cicada’s mechanical whir. The buzzing of mosquitoes is a high-pitched whine created by wings beating hundreds of times per second, but this sound is localized and low in volume.