The Cicada: Many Things To Many People


In this century of rapid scientific discovery, there still exist natural phenomena with the power to inspire wonder and mystery. The cicada, an insect known since ancient times, is one such phenomenon. Because scientific
knowledge of the cicada contains many gaps, these mysterious insects can still stimulate our imagination or lead
us into confusion. At the present time, the cicada is many things to many people: it is a curiosity that should be approached scientifically; it is a source of superstition and dread; it is also little more than an annoying, seasonal inconvenience.
The cicada is a stout, black insect about an inch in length. Various species of this insect can be found all over North of the America. When the cicada is at rest, its large, transparent, veined wings are folded over the top of its body and extend about a quarter of an inch beyond it. Cicada wing veins are and information reddish orange in color, as are its eyes and legs. The front legs are sharp and crablike, allowing the animal to hold tight to the bark of trees. The species of American cicada most written about by scientists and most wondered about by the general public is known as the periodical cicada. Its scientific name is Magicicada septendecim. This species of cicada appears above ground only once every seventeen years.
What the cicada does underground for most of its seventeen-year life span was a mystery until fairly recently. In the early part of this century, a man named C.L. Marlett, who worked for the United States Department of Agriculture, decided to find out. He began burying cicada eggs in his backyard and digging them up periodically for observation. He soon found out that the cicada begins life as a tiny nymph about six hundredths of an inch in length. A nymph is an immature insect, before it has fully developed
wings or reproductive organs.
During their sixteen years and ten and one-half months underground, cicada nymphs are nestled against tree roots from which they gently suck the juices. Nourished by this root sap, they begin to grow. They shed their skin four times before they reach adult size.
Once matured, a cicada does not necessarily leave its underground nursery. All cicadas of the same generation in a region wait for a seventeenth spring before they come creeping forth from the ground as a group. The eeriness of this group effort has puzzled humans for centuries. People have responded to the mystery with a host of superstitions, educated guesses, and scientific theories.
One of the earliest explanations for the mass appearance of cicada populations after their long absence in an area was that the insects had come to foretell war. This idea stems from an observation of the adult cicada shortly after it appears above ground. It immediately sheds its skin for the last time and begins to darken in color. Near the outer edge of its front wings, a black mark appears that looks distinctly like the letter W. Some thought this W stood for war. In the past, people who saw a group of cicadas emerge from the ground like an invading army were filled with panic. The sight was especially frightening because literally millions of insects can appear within an area of a few square miles.
Later explanations for the mass appearance of cicadas stem from more scientific observations. Dr. L. L. Pechuman, a professor at the New York State College of Agriculture and Life Sciences at Cornell University, has suggested that coming above ground only once every seventeen years is an excellent way for a species to discourage its natural enemies. Perhaps the cicadas have evolved a special kind of biological time clock to protect them from predators.
James Heath, an insect physiologist at the University of Illinois, theorizes that the cicadas all emerge at around the same time in a certain year because the soil has reached a temperature of 64 degrees. Theories like this have still not been proved absolutely, but they do a lot to dispel the fear, awe, or confusion experienced by many people who witness millions of cicadas surfacing at once.
Once cicadas surface, they lose no time. At this point in This their life cycle, they