Locusts are a type of grasshopper known for forming vast swarms that impact agriculture. Beyond their visual presence, locusts also produce various sounds. This article explores the specific noises locusts make, how they produce them, the reasons behind their vocalizations, and how their sounds differ from those of other common insects.
The Distinctive Sounds of Locusts
Locusts produce a range of sounds, including buzzing, clicking, crackling, or snapping. Some species create a “violin-like buzzing sound” by rubbing body parts. These noises may be heard day and night, varying by species and activity.
Individual locusts produce soft, muffled buzzing. However, large swarms amplify these sounds significantly, creating a continuous, intense noise. For example, band-winged grasshoppers, a type of locust, produce a loud snapping or cracking sound with their wings while flying, a process known as crepitation.
How Locusts Produce Their Sounds
Locusts primarily create sound through stridulation, a process common among many insects. This involves rubbing two specialized body parts together, typically their hind legs against their forewings.
Stridulation uses a “file” and a “scraper.” Short, peg-like bumps on the inner surface of the hind femurs act as the file, rubbing against a hardened vein or edge on the closed forewing (the scraper). This generates vibrations that produce sound. Some locusts also create sounds through crepitation by snapping or clapping their wings during flight, resulting in crackling or rattling noises.
Why Locusts Make Noise
Locust sounds serve as a form of communication, conveying messages to other locusts. A primary purpose of these vocalizations is mate attraction. Males use specific songs, produced through stridulation and crepitation, to signal their presence and attract females for reproduction.
Sounds are also used for territorial defense, helping locusts protect their space from rivals. These noises can also act as warning signals to deter predators. For example, locusts perceive ultrasonic signals, like those from bats, and respond by changing flight patterns or increasing wingbeat frequency to evade capture.
Locust Sounds vs. Other Insects
Distinguishing locust sounds from other insects, such as crickets and cicadas, aids identification. Crickets typically produce melodic chirps by rubbing their wings together, a different form of stridulation compared to locusts. Crickets also have longer antennae than locusts.
Cicadas are known for their loud, continuous buzzing or droning sounds, reaching volumes up to 120 decibels. Unlike locusts, cicadas produce these sounds using specialized organs called tymbals, located on their abdomen. These ribbed membranes rapidly buckle, creating the characteristic cicada song, primarily used by males to attract mates. While “locust” is sometimes mistakenly used for cicadas, especially in North America, locust sounds are generally not as loud as those of cicadas.