As darkness settles, a distinct chorus of buzzing and chirping often fills the night air. These nocturnal soundscapes are a common experience, hinting at a hidden world of insect activity. Identifying the sources of these sounds reveals an intricate natural symphony.
Common Nocturnal Buzzers
Among the most prominent insects contributing to the nighttime chorus are cicadas, katydids, and crickets. Cicadas are known for their loud, continuous buzzing or whirring sound, sometimes resembling an electric string trimmer or power saw. While often associated with daylight, some cicada species vocalize into the evening.
Crickets produce a rhythmic chirping sound, often described as musical due to its relatively pure and low frequencies. Only male crickets generate these sounds. Katydids contribute a raspy, buzzy, or whiny call, often interpreted as “katy-did” or “katy-didn’t.” These insects are primarily active and vocal after dark.
The Science of Sound Production
Insects employ various biological mechanisms to produce their characteristic sounds. Crickets and katydids use stridulation, rubbing specialized body parts together. Male crickets create chirps by rubbing a scraper on one forewing against a file-like ridge on the other. This rapid friction generates vibrations amplified by their wings. Katydids also stridulate by rubbing their forewings together, with one wing’s sharp edge moving against a file-like ridge on the other.
Cicadas utilize a different, often louder mechanism involving specialized organs called tymbals. These ribbed membranes are on the sides of the male cicada’s abdomen. Muscles rapidly contract, causing the tymbals to buckle inward and produce a series of clicks. The rapid succession of these clicks results in the continuous buzzing sound, amplified by the cicada’s hollow abdominal cavities and internal air sacs.
Purpose of the Nocturnal Chorus
The sounds produced by these insects serve fundamental biological purposes, mainly centered around reproduction and survival. Male insects vocalize at night primarily to attract mates. Each species has a unique calling song, enabling females to identify and locate partners.
Beyond attracting females, these auditory signals also play a role in territorial defense. Males use their calls to communicate their presence and warn off rival males from their established areas. Cicadas may also produce sounds when disturbed or threatened, such as a squawk when handled.
Identifying the Sound Source
Distinguishing between insect sounds at night involves paying attention to specific auditory characteristics and environmental cues. The frequency, rhythm, duration, and overall pattern of the sound help differentiate species. Crickets produce regular, lower-frequency chirps with distinct pauses between calls. Katydids emit a higher-pitched, raspy, or buzzy sound, often pulsed in distinct syllables.
Considering the time of night and season also provides clues. Katydids and crickets are predominantly nocturnal, while the loudest cicada choruses are heard during the day and at dusk. Observing the sound’s general location is also helpful. Katydids call from high in trees, whereas crickets are heard closer to the ground or in low-lying vegetation.