Katydids are common nocturnal insects known for their distinct sounds that fill warm summer nights. These creatures communicate through a variety of calls, and their presence is usually detected by sound rather than sight. Katydids are widespread, with approximately 6,400 species globally, each contributing to the intricate soundscape of their habitats.
How Katydids Produce Sound
Katydids generate sounds through stridulation, rubbing specialized body parts together. Male katydids use their forewings for sound production. The right forewing has a sharp “scraper,” while the left forewing, which overlaps the right, contains a file-like ridge with tiny teeth on its underside. Sound is created when the katydid rapidly moves the scraper across the file. This friction causes vibrations in the wings, amplified by clear, thinned membrane areas, sometimes called “mirrors” or “speculae.” This process allows for the production of frequencies from 3-5 kHz up to and beyond 20 kHz, making some calls ultrasonic and inaudible to humans.
The Purpose of Katydid Calls
Katydid calls serve several biological functions, primarily communication. The most significant purpose is mate attraction, where males produce calls to signal their presence to receptive females. Species-specific songs help females identify potential mates from their own species, even among numerous other singing insects. Calls also play a role in inter-male communication, allowing males to establish and defend territories. The loudness and pattern of a male’s song can influence female choice and deter rival males. Some katydid species synchronize their calls in large choruses, creating a resounding pulsation of sound that can attract more distant females.
Identifying Katydid Sounds
Katydid sounds are often described as sharp, raspy pulses, distinctly different from the continuous chirps of crickets or the buzzing of cicadas. A common True Katydid’s call is frequently likened to the phrase “ka-ty-did, ka-ty-didn’t,” a helpful mnemonic for identification. These calls typically consist of two to four notes delivered in a distinct rhythm.
Katydids are predominantly nocturnal singers, calling from dusk into the night, often from high in trees. This nighttime activity contrasts with cicadas, which primarily call during daylight hours. The tempo and pattern of katydid songs can vary by geographic location and with temperature, becoming slower as temperatures drop. Their rhythmic patterns make them a recognizable part of the summer night soundscape.