MAY
2007

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

5-10-07

Sounds Made by Insects Difficult to Mimic

Most people are familiar with sounds produced by insects. Some insect sounds are the result of wing vibration during flight. Such is the case with the buzz of bees. Sounds that are the byproduct of flight generally do not serve a specific function to the insect.

But the sounds of insect wings might send a message to other animals. For instance, the characteristic buzz of a bee or a fly could mean the potential for a sting or bite. Rimsky-Korsakov was so impressed with such sounds that he used high-pitched violins to represent the queen in his classic composition, "Flight of the Bumble-bee."

Paying close attention to the pitch of the sound of a bee can tell you something about the insect. For instance, an active honey bee produces 435 wing vibrations per second. She is humming in the pitch of A. When a honey bee gets tired, the number of vibrations goes down to 326, and we hear an E. House flies vibrate their wings 21,120 times per second, which is an F sound. And, I guess, house flies never get tired, since they apparently always buzz in F.

Most insect sounds, though, serve a specific function. Such as startling a predator, defining a territory or attracting a mate. Sounds are produced by insects in a variety of ways. Some insects, such as grasshoppers and crickets, stridulate. Technically, that means that these insects rub one body part such as a wing or leg on another body part to produce the clicks and scrapes so familiar to most of us.

Cicadas produce their sounds by vibrating a membrane on their thorax. These insects are drummers. Maybe "noise-making" is a better description of their sound production. At least anyone who has been in the vicinity of a large number of singing cicadas can vouch for the fact that cicadas make up in volume for any quality deficiency in their song.

Humans have long tried to use our language skills to capture the sounds produced by insects. But it is a difficult task. For instance, the name of one group of insect songsters is the katydid. That name is based on the sound of one type of katydid, which to some listeners appeared to be calling "katy did, katy did, katy did!" What katy did has yet to be answered. Maybe the insect didn't do anything at all. Because as entomologists point out, there are times when katydids produce a three-syllable sound that sounds like "katy didn't!" Oh well, the name is inappropriate anyway. As it turns out, which is the case for all singing insects, it is not the female that sings. So katy is a male!

The name cricket comes from the fact that some French-speaking folks back in days gone by described the chirp of this insect as "cree kay." So, today, we use an English version of the sound to give a name to this group of insects.

A recent delightful book called "The Songs of Insects" by Elliott and Hershberger includes a CD of insect sounds, as well as wonderful pictures of the insect songsters. In the book, the authors describe the sounds in terms of pulse rates and frequency. For instance, the four-spotted tree cricket produces a continuous trill of about 40 pulses per second at a frequency of 4 kHz.

They also sometimes try to describe the sound in words. For instance, the sword-bearing conehead, a type of grasshopper, sounds like "tst-tst-tst-tst-tst-tst..." Another goes "zee-zee-zee-zee." The common true katydid produces a harsh "ch-ch-ch-ch." Another katydid produces a sound of zits. Still another, a two-part sound of "zeee-dik!"

Of course, it is not easy to make a sound like an insect. But some of us try. Some years ago, I was practicing my repertoire of insect sounds before heading off to teach a class about insect communication. Right in the middle of my best rendition of tsts, ch-chs, zees and zits, a tap on my door was followed with the question of, "Are you OK?"

It was probably better not to try to answer that question!

 

Writer: Tom Turpin
Editor: Olivia Maddox