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 have only 5 or 6 weeks of life
remaining. They head quickly for the nearest tree or bush and climb onto it.
Then, holding onto the bark with their clawlike front legs, they shed their skin
for the last time and become large-winged adults. These adults will mate, and
the females will then dig into the tender bark of small twigs to deposit their
eggs. The adult cicadas die shortly after the mating and egg- laying process has
occurred. The eggs hatch a few weeks after being laid, thus yielding a new
generation of nymphs. The nymphs fall to the ground from the trees and then
crawl to the soil, renewing the 17-year cycle. Opinions remain divided
concerning the amount of harm done by cicadas to trees and to bushes. The
Pilgrims who is came to the New World assumed that cicadas were locusts. An army
of locusts can destroy acres of greenery in record time by biting and chewing
leaves and stems. To the present day, the Pilgrim misidentification of cicadas
has stuck, and many people still refer to cicadas as "seventeen-year
locusts." Millions of plant lovers use the name as an excuse to fear and
detest cicadas. In reality, cicadas can only suck-not bite-tender plant tissue;
and adult cicadas eat little if at all during their five to six weeks above
ground. According to Jane E. Brody, who writes science articles for The New York
Times, the only harm done to trees by cicadas occurs during egg-laying. This
egg-laying leads only "to a kind of natural pruning and an injury that all
but the young trees can easily withstand." However, Richard Maffei, author
of Insects in Your Garden, strongly disagrees. He maintains that "leaves on
twigs and branches so punctured usually turn brown, but hang on as an eyesore
for weeks before the branch breaks and falls to the ground." Few disagree
with the opinion that the skins shed by cicadas aboveground are an unsightly
form of natural litter. A book by Peter Farb called Insects speaks
disapprovingly of the "junk yard of skins" shed by a swarm of cicadas
in an Indiana orchard in 1953. Jane E. Brody describes a time in the Northeast
in 1970 when passersby had to "skip like schoolchildren’ to avoid crunching
the piles of cicada bodies beneath their feet. This litter is added to by birds
who eat the cicadas, spitting out their wings in the process. For people with
sidewalks to sweep and yards to clean, such animal remains can be a real
nuisance. This is especially true in the case of cicadas, as 20,000 to 40,000
can appear beneath a single tree. As cicada invaders appear, they are also
likely to leave their traces in lawns, flower beds, and fields. Cicada nymphs
burrowing out of the soil in search of a tree can leave a hole as large as
one-half inch across. Such honeycombing of the soil can be very dismaying to
those who take pride in a well-kept lawn. During a 1987 appearance of cicadas in
the Washington, D.C., area, the United States Agricultural Research Service was
plagued by telephone calls from distraught people who wanted to know why their
lawns suddenly had holes. Of all the phenomena related to cicadas, their song,
or-as some call it-their racket, has aroused the most comment. Attached to the
underside of a cicada’s abdomen is a pair of large drumheads. These drumheads
are operated by powerful muscles that set them vibrating. The loud, shrill sound
produced has been compared to the creaking of an unoiled door hinge, a jet about
to land, or the sound of a car motor about to break down. Of course, the cicada
sound with which humans are familiar is actually made by thousands of cicadas
singing together, and it has a hypnotic, droning effect. Only male cicadas are
equipped to sing. The noise attracts females, who eventually mate with their
serenaders. Scientists are beginning to suspect that a very loud noise, produced
by a giant chorus of male cicadas, is necessary for successful mating.
Accordingly, small groups of cicadas, which cannot produce enough noise, tend
not to mate and do not produce a new generation. The human reactions to cicada
music range from fascinated disbelief to annoyance to panic. The Guiness Book of
World Records lists male cicadas as the world’s loudest insects maintaining that
their abdominal drums vibrate at a rate of 7,400 pulses per minute. The noise
produced has been described by the United States Department of Agriculture as
sounding something like "Tsh-ee-EEEE-e-ou!" Motorists driving through
a town populated with lovesick cicadas may stop their cars and open the hood to
find out what is wrong with the engine. People who sleep during the day-the time
when cicadas sing-often have to resort to earplugs. Finally, most people realize
that there is no remedy other than to put up with this sound for five or six
weeks. After all, it only occurs in a particular area once every seventeen
years. All in all, the cicada is a creature little understood by most humans.
Throughout the centuries it has been misnamed or mistakenly feared. Legend has
attributed terrible powers to it. The cicada has been called everything from a
plague to an omen of war to a backyard nuisance. Perhaps, in years to come, as
scientists discover more about this infrequent visitor, it will lose some of its
mystery. Only then, in the human mind, will it join the familiar ranks of such
warm-weather insects as the mosquito and the butterfly.
Brody, Jane E. "After 17 Years, Cicadas Prepare for Their Roaring
Return." The New York Times, May 12, 1985, pp. C1, C3. "Cicadas."
The Encyclopaedia Britannica, vol. 3, 1980 ed. Farb, Peter, and the Editors of
Time-Life Books. The Insects. New York, New York: Time-Life Books, Inc., 1970.
"The Living World." The Guiness Book of World Records. New York, New
York: Sterling Publishing Company, Inc., 1987. Maffei, Richard. Insects in Your
Garden. New York, New York: Dalton, 1984.