AUGUST
1997

 

 

 

By
Tom Turpin
 
Professor of
Entomology
Purdue University

 

 

 

 

 

8-14-97

The Trees Are Alive With The Sounds Of Cicada Music

During August and September, insect songsters are at their loudest. One of the most recognizable insect sounds belongs to cicadas.

Cicadas are percussionists. They produce their sound by vibrating a pair of membranes located on the abdomen.

Cicadas have long been admired by humans because of their singing habits. Many scholars believe that Aesop's Fable about the grasshopper and the ant is really about a cicada, not a grasshopper. Both insects seem to be wasting time singing during the fall when the ants are busy laying in their winter's store of food.

Grasshoppers and cicadas share few characteristics except singing, but the two types of insects were confused when European settlers first colonized North America. The word locust had been used since biblical times to describe migratory grasshoppers. Early settlers called the great masses of cicadas they encountered locusts. So the settlers didn't distinguish between these two insects, both of which occur in large numbers, fly and sing. That confusion exists today. Many North Americans use the word locust for the insects known in the rest of the world as cicadas.

Ancient Chinese people also admired the cicada, so much so that it was considered a magical insect. It appears frequently in Chinese art and jewelry because of the ancient high esteem for the insect.

Cicadas have unusual and interesting life cycles. The periodical cicada has the longest life span of any insect other than some queen termites of Africa. Periodical cicadas have 17- or 13-year life cycles.

Adult periodical cicadas emerge from the soil, where in their immature stage they would feed on the sap from roots. The males do the singing to attract females for mating. The mated females lay eggs by cutting small slits in the bark of twigs. The newly hatched immature drops to the ground and enters the soil, where it will feed for years and years.

Other cicadas are not as long lived as the periodical, but still spend from two to five years underground. That is the case with the so-called annual cicada. It is called the annual cicada because some emerge each year. The periodical cicadas do not emerge every year in a given area, although some part of the eastern United States will experience an emergence each year.

Cicadas are hard to ignore when they emerge in great numbers and begin to sing. The noise can be deafening. Even the great French naturalist Fabre was interested in the singing habits of this insect. He believed, in spite of the sound produced, that cicadas could not hear. His belief was based on the fact that, unlike most singing insects, cicadas would continue to sing around disturbing noises. In an interesting experiment, he convinced the town fathers to shoot cannons in the town square in an attempt to quiet the cicada noise. The cannons were fired, the cicadas kept right on singing, and Fabre concluded that they did so only because they were deaf. As it turns out cicadas aren't deaf — they're just cantankerous when it comes to their singing!

 

Writer: Tom Turpin
Editor: Andrea McCann