8.2 Lesson 2: How Insects Make Sounds

Listen to the video and think about...HOW do insects make these sounds??

How do insects make sounds?

We live in a noisy world. One of the noisiest inhabitants on Earth are insects. No matter where you go, you can’t escape them. It is estimated that 75% of the over 8 million different species of life on Earth are insects. No wonder it’s impossible to escape their constant, noisy chatter.

But how do insects make sounds?   As you read, think about what is similar between how sound is produced in all these insects and what you have figured out in your investigations in class about how instruments produce sound.

Crickets

Among the noisiest of insects are crickets. Only the male crickets make sounds, and surprisingly, not all species of crickets produce sound. Crickets make sounds for many reasons, but one of the main reasons is for male crickets to attract female mates.

​When a male cricket wants to attract a mate, he lifts up his wings and rubs them together. Each wing has "teeth," much like a comb does. The chirping sound is created by running the top of one wing along the teeth at the bottom of the other wing. When the cricket does this, the teeth strike each other, and thin portions of the wing deform, change shape, and vibrate to make the sound.

Grasshoppers

Grasshoppers are another group of insects that use sound in their everyday life. One way they make sounds is by rubbing one of their hind legs, which has rows of pegs on the inside, against the stiff outer edge of their wing. These sounds are produced in order to find a mate and protect their territory. Grasshoppers can also make loud snapping or cracking sounds with their wings as they fly. They “pop” their wings by causing the membranes between the veins to stiffen, leading them to change shape and vibrate. This is another way to get attention when they are trying to court another grasshopper for mating.

Cicadas

Another noisy insect is the cicada. Cicadas make the loudest mating song of any insect or animal. Some species can produce songs as loud as the sound from a car’s speakers at maximum volume.

The male cicada makes sounds by changing the shape of two membranes in his ribs called tymbals. By contracting a muscle, the cicada bends the membrane inward, producing a loud click. As the membrane snaps back, it clicks again. This produces vibrations that move through his abdomen to make the sound louder. Cicadas also make sounds to attract mates and protect territories.

Observe the slow-motion videos on the next two slides...

Think about the sound that a bee, mosquito, or fly makes as it flies near your ear. Each produces a buzzing sound as they fly. On the following two slides, analyze the insects flying to figure out what might be producing these sounds as they are doing this.