How Do Grasshoppers Produce Sound?

Male grasshoppers will make a singing sound by rubbing a hind leg against one of their hard forewings. The rough leg causes the wing to vibrate and make a sound, almost like a bow playing a cello.

Grasshoppers and orthopterans in general, produce sounds to attract mates or protect their territories. Grasshoppers can be identified by their unique songs, which differ slightly from species to species. Unlike crickets, grasshoppers do not rub their wings together to make noise. Male grasshoppers produce sounds to attract a female mate, doing so in one of two ways – stridulation or crepitation.

• Stridulation involves rubbing one body part, which acts as a rasp, against another, which acts as a scraper. Most grasshoppers stridulate to make their characteristic sounds. In grasshoppers, a row of pegs along the inside of the hind leg acts as a file, or rasp. The grasshopper rubs this leg surface against the thickened forewing, causing a vibration and thus a sound.
• A few grasshoppers, most notably some band-winged grasshoppers in the family Oedipodinae, use an entirely different method of sound production, called crepitation. These grasshoppers snap their hind wings rapidly as they fly, making a distinct crackling sound.

Male grasshoppers typically do all the singing, mostly to attract females. The females rarely make sounds, but it has been observed that they do so in the courtship ritual.     Males also make sounds to warn other kinds of insects to stay away. Some grasshoppers even make alarm calls when danger is near.

Many long-horned grasshoppers can sing, too. But they use their two front wings instead of their legs. One wing has a “file.” The other wing has a “scraper.” The grasshopper rubs these two parts together to make a song.  The intensity of the sound and its duration has a distinct flucuation pattern across the sonic frequency spectrum from 5 KHz to 35 KHz.  Interestingly, they perceive and emit sound from multiple directions simultaneously.   In the frontal direction, ultrasound contributes approximately one-quarter of the radiated sound intensity, whereas in the other directions the sonic and ultrasonic contributions are approximately equal.

Scientists have discovered that each leg produces a harmonized group of tones with the other in a pattern similar to what is referred to as an audio comb filter with peaks centered at 5, 6.3, 8, 10, 12.5, 16, 20, 25 and 31.5 kHz. Human auditory range is from 20Hz to 20 KHz, meaning that a large portion of grasshopper/locust communication is inaudible and only detected with sensitive audio equipment capable of operating in the ultrasonic range.  What makes this significant is that they are simultaneously communicating with biochemical feedback and sound in multiple channels and directions all in real time.  Grasshoppers truly are a highly evolved and amazing species.