How Insects Like Crickets and Cicadas Chirp and Sing

Grasshopper.
Grasshoppers, crickets, and cicadas all make audible sounds. Getty Images/Kester Looser/EyeEm

By late summer, the most common singing insects—grasshoppers, katydids, crickets, and cicadas—have matured and started their courtship calls in earnest. The air is filled from morning to night with their buzzes and chirps. 

Crickets, katydids, and grasshoppers belong to the same order, Orthoptera; cicadas are from the order Hemiptera. How do these insects make sounds? The answer varies depending on the insect.

Crickets and Katydids

Field cricket.
Crickets produce by rubbing their wings together. Life On White/Photodisc/Getty Images

Crickets and katydids produce sound by rubbing their wings together. At the base of the forewing, a thick, ridged vein acts as a file. The upper surface of the forewing is hardened, like a scraper. When the male cricket calls for a mate, he lifts his wings and pulls the file of one wing across the scraper of the other. The thin, papery portions of the wings vibrate, amplifying the sound. This method of producing sound is called stridulation, which comes from Latin meaning "to make a harsh sound."

Only male crickets actually produce sounds and not all species of crickets chirp.  Crickets actually produce different calls for different purposes. The calling song, which may be heard for distances up to a mile, helps the female find the male. The female responds only to the unique, characteristic sound of her own species. Once she is near, the male switches to a courtship song to convince her to mate with him. And, in some cases, the male also sings a post-copulation celebratory song. Crickets also chirp to establish their territories and defend it against competing males.

Some crickets, such as mole crickets, dig tunnels in the ground with megaphone-shaped entrances. When the males sing from just inside their burrow openings, the shape of the tunnel amplifies the sound enabling it to be heard from further distances.

Unlike crickets, among some species of katydids, the females are also capable of stridulation. Females chirp in response to the shrill of the males, which sound like,"katy did," which is how they received their name. The males use this sound for courtship, which occurs late in the summer.

Grasshoppers

Grasshopper.
Grasshoppers make sounds in one of two ways – stridulation or crepitation. Getty Images/E+/li jingwang

Like their cricket cousins, grasshoppers produce sounds to attract mates or protect their territories. Grasshoppers can be identified by their unique songs, which differ slightly from species to species. 

Grasshoppers stridulate like crickets, rubbing their wings together. Additionally, males and sometimes females make loud snapping or crackling sounds with their wings as they fly, especially during courtship flights. This unique mode of sound production is called “crepitation,” the snapping sounds apparently being produced when the membranes between veins are suddenly popped taut.

Cicadas

Cicada.
Cicadas make sounds by contracting special muscles. Getty Images/Moment Open/Yongyuan Da

The sound of the cicada love song can be deafening. In fact, it is the loudest song known in the insect world. Some species of cicadas register over 100 decibels when singing. Only the males sing, trying to attract females for mating. Cicada calls are species-specific, helping individuals locate their own kind when different kinds of cicadas share the same habitat.

The adult male cicada (order Hemiptera) possesses two ribbed membranes called tymbals, one on each side of its first abdominal segment. By contracting the tymbal muscle, the cicada buckles the membrane inward, producing a loud click. As the membrane snaps back, it clicks again. The two tymbals click alternately. Air sacs in the hollow abdominal cavity amplify the clicking sounds. The vibration travels through the body to the internal tympanic structure, which amplifies the sound further.

If a single male cicada can make a noise over 100 decibels, imagine the noise produced when thousands of cicadas sing together. Males aggregate as they sing, creating a cicada chorus known as a lek. 

A female cicada that finds a male attractive will respond to his call by doing a maneuver descriptively called the "wing flick." The male can both see and hear the wing flick and will reply with more clicking of his tymbals. As the duet continues, the male makes his way toward her and begins a new song called the courtship call.

In addition to its mating and courtship calls, the male cicada makes noise when startled. Pick up a male cicada, and you'll probably hear a good example of the cicada shriek. 

Sources

Katydid.
Katydid. Getty Images/Johner Images