You've probably heard lots of bug sounds. Remember the familiar chirping sound of a cricket on a warm summer evening? Most sounds produced by insects are used to attract mates. The crickets you hear are males calling to females. The tiger moths that we study make sound too, but you can't hear them. They are too high in pitch. Imagine playing middle C note on a piano. Now go up an octave to the next highest C. You would have to do this 7 times to have a pitch as high as that of a tiger moth. Normal pianos do not go up that high in frequency. Why not? Sounds above our normal range of hearing are called ultrasound. When we lower the pitch of moth sounds so that you and I can hear them they sound like clicks - you can simulate moth sound by running your thumb over the teeth of a comb.
How does a moth make sound?
The organs that moths use to produce sound are called tymbal organs. The word rhymes with cymbal - another much larger sound making device. A tymbal organ is a tiny little blister of cuticle on the middle portion of the moth's body just above its third pair of legs. Each tymbal has a row of ridges along its front edge. Each ridge is called a microtymbal and makes its own personal click. The moth can make the tymbal buckle in and out using muscles hidden underneath. Each time the tymbal buckles it makes a series of clicks. Each time it relaxes it makes a second series of click. If you would like to hear a moth make sound click on the button shown below. Next time you are finished drinking a can of soda squeeze the can and listen to the clicks. When you release the can it makes sound again. This is just like how moths produce sound, only they use their tymbal organs instead of a soda can.
SEM by Margie Rodgers
This is an example of a tymbal from an arctiid moth.
Why do moths make ultrasonic clicks?