Katydids are common nocturnal insects recognized by the distinct sounds they produce during warmer months, a familiar part of the nighttime soundscape. This article explores the specific sounds katydids make and the biological processes behind their acoustic displays.
The Signature Katydid Song
Katydid sounds vary significantly by species but share common characteristics. The common true katydid (Pterophylla camellifolia) is known for a repetitive song often interpreted as “katy-did, katy-didn’t” or “katy-did.” This distinctive call typically consists of two to three harsh pulses, often with pauses lasting up to a couple of minutes. These sounds are described as raspy, buzzy, or tick-like, sometimes resembling a zipper or a Moroccan shaker.
Katydid songs are loud and can be heard from high in trees, where these insects commonly reside. The calls are typically given from dusk into the night. Some species produce complex songs, while others have simpler, more irregular patterns compared to the consistent chirps of other insects. Large choruses can sometimes drown out other sounds in a woodland environment.
The Mechanics of Sound Production
Katydids produce sounds through stridulation, rubbing specialized body parts together to create friction and vibrations. Male katydids typically generate sound by moving a sharp edge on their right front wing rapidly against a file-like ridge on their left front wing. This mechanism is described as a “scraper” (the sharp edge) moving across a “file” (the ridge with tiny teeth).
The vibrations from this rubbing cause thinned, transparent wing cells to resonate, amplifying the sound. While most sound production comes from males, some female katydids also produce sounds, though less common. Katydids minimally elevate their wings during sound production, just enough for the necessary vibrations.
The Purpose Behind the Calls
Katydids primarily produce sounds for mate attraction. Male katydids broadcast their calls to attract females. Each species has a unique call pattern, allowing females to identify and respond to appropriate partners. This species-specific “song” ensures successful reproduction by preventing interbreeding with other species.
Beyond attracting mates, these calls also serve other functions. Some calls are associated with territorial defense, deterring other males from their space. In some instances, females might respond to a male’s song with a specific call, further facilitating courtship. The intensity and pattern of the calls can also vary with temperature, with warmer conditions often leading to more frequent trills.
Differentiating Katydid Sounds
Distinguishing katydid sounds from other nocturnal insects, such as crickets and cicadas, involves key differences. Katydids are primarily nocturnal, their calls heard at night, unlike most cicadas, which typically sing during the day and early evening. Cicada sounds are often described as a louder, continuous, high-pitched buzz, whine, or rattling, sometimes reaching up to 100 decibels.
Crickets, also nocturnal, produce a more consistent, rhythmic “chirp” that sounds more musical due to purer and lower frequencies. Katydid sounds, in contrast, are often more raspy, irregular, or broken. They are described as short, sharp scraping noises or a series of clicks, rather than a continuous buzz or a steady chirp. While crickets and katydids both use stridulation, the specific sound they produce helps differentiate these common summer night musicians.