AUGUST
1998

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

8-13-98

"The Sons of the Cicadas" in Concert this Fall

Each fall, one of nature's singing groups, "The Sons of the Cicadas,” begins its annual serenade. Cicadas are insects that long have long been recognized for the sounds they produce.

Generally, cicada sounds are considered songs. Like music of any kind, quality is a value judgment rendered by the listener. To the female cicada, the sounds produced by the male cicada-and only the males produce sound-are the lilting strains of the sweetest love song. She uses the music to select a mate.

When several hundred cicadas are crooning in concert, the sound can be deafening. Some folks think that the decibel level, as well as the monotony, places the sound in the category of noise.

Noise or song, the sound is produced by the insect with a pair of organs located on the first segment of the abdomen. The sound-producing organ is a cavity covered with a lid. Inside is a membrane called a tymbal that is vibrated by muscles to produce the sound.

Cicada sounds long have been noted by humans. Ancient Chinese attached religious significance to the sound. Because of translation errors, it actually may have been the cicada and not the cricket in Aesop's fables that sang all summer and failed to plan for the winter, as did the ant.

In folklore of the United States, the first sound of the dog-day cicadas is said to predict the first frost in six weeks. In this case, the folklore is probably close to the truth. The common name of the dog-day cicada is based on its emergence from the soil during that period of time known as the "dog days of summer.” From the dog days, it's only a couple of months until the first frost in most years in the Midwest.

There are two common types of cicadas. The dog-day cicadas are mostly black insects with green markings. The life cycle lasts from two to five years with the immatures feeding underground until the emergence. Each year, some of the dog-day cicadas emerge. They are sometimes called the annual cicadas, since we see some every year.

The other major group of cicadas are called periodical cicadas. Periodical cicadas are common in the eastern part of the United States. They have a life cycle that lasts 13 or 17 years. There are three species that live 13 years and three species that live 17 years.

The periodical cicadas are smaller than dog-day cicadas and have reddish wing veins. Periodical cicadas emerge during May and June, sometimes in very large numbers.

Both groups of cicadas lay their eggs in the twigs of trees. This process sometimes can damage small trees but generally does no permanent harm to mature trees. All cicadas emerge from the soil where they have sucked sap from tree roots during their development stages. After emerging, they crawl up a tree trunk or post and emerge as an adult, leaving their "shell” hanging on the bark.

Then, it's time to tune up the vocal chords, or rather tymbals, and join the other males in a rousing rendition of "The Bachelor Seeks a Wife.”

 

Writer: Tom Turpin
Editor: Olivia Maddox