Part 1

Produced by Tom Cosmas compiled from images made available by The Internet Archive

Transcriber Notes

Emphasis displayed as Italics and =Bold=. Whole and fractional parts of numbers are displayed as 1-5/8.

THE

PERIODICAL

CICADA

The 17-Year Locust

U.S. DEPARTMENT OF AGRICULTURE • Leaflet No. 310

THE PERIODICAL CICADA

No other insect in North America excites as much curiosity and wonder as does the periodical cicada when it makes its sudden, springtime appearance at intervals of 17 or 13 years.

After years of living in underground tunnels, millions of cicadas issue from the earth as if by a predetermined signal, undergo startling transformations, and spread through nearby trees and bushes. From morning till night they fill the air with their weird, droning song. In a few weeks, after mating and laying eggs, they die.

The periodical cicada, often erroneously called the 17-year locust, is widely distributed over the eastern half of the United States, and occurs nowhere else in the world. In the North its life cycle is completed in 17 years; in the South the cycle is completed in 13 years.

The adult insect is about 1-5/8 inches long. Most of its body is black. The legs are reddish, some of the veins in the nearly transparent wings are orange, and the eyes are red.

The periodical cicada, known scientifically as Magicicada septendecim, is closely related to common cicadas, which appear every year. The common cicadas, called harvest flies and dog-day cicadas, appear later in the season than the periodical, and the adults live longer. Their whirring song, which is slightly similar to that of the periodical cicadas, but has less variation in the notes, is a "lazy" sound that we associate with the languorous days of late summer.

Cicadas have a beak for piercing plant tissue and drawing sap into their bodies. They are large relatives of leafhoppers, aphids, scales, and other sucking insects.

Some Misconceptions

The dramatic and bizarre elements in the life cycle of the periodical cicada have caused the insect to be regarded, not only with curiosity, but also with superstition and fear.

Even before the white man came to North America, the Indians thought its periodic appearance had an evil significance.

Early American colonists had never seen the periodical cicada. They were familiar with the Biblical story of locust plagues in Egypt, but were not sure what kind of insect the story referred to. When the cicadas appeared suddenly by the millions, some of the colonists thought a "locust plague" had been visited upon them.

To some extent the confusion between cicadas and locusts exists today; cicadas are commonly called locusts. The term "locust" is correctly applied only to certain species of grasshoppers. Migratory locusts, which comprise one of these species, ruined crops in Egypt in Biblical times. They still damage crops in that country and in many other parts of the world.

Even when the periodical cicada is not confused with some other insect, its appearance in overwhelming numbers arouses fear that crops will be destroyed. But the cicada does not feed on foliage of any kind. If the adults feed at all, they do so by inserting their beaks in bark and sucking juice. Although the adults cause no feeding damage, the adult females make injurious punctures in twigs and limbs of trees and bushes with their egg-laying apparatus.

A false belief that is much less widely held today than formerly is that the distinct black =W= toward the outer end of the front wings foretells war. The mark is a characteristic of the species, and is produced by deeper pigmentation of the veins.

The cicada cannot sting, and any story is mythical that tells of cicadas poisoning fruit by stinging it.

How Cicadas Develop

Using the blades of a curved, sawlike egg-laying apparatus on the end of the abdomen, the female cicada punctures the bark of a twig and makes a pocket in the wood. In the pocket she lays 24 to 28 eggs in 2 rows. She then moves forward, cuts another pocket, and lays more eggs. She continues this process until 5 to 20 pockets have been made in the twig. The pockets are placed close together in a straight row. Sometimes they form a continuous slit 2 or 3 inches long. Moving from one twig to another, a cicada lays a total of 400 to 600 eggs.

The eggs are laid in twigs and small branches of a wide variety of trees and plants. They hatch in 6 to 7 weeks. The immature insects are called nymphs.

The newly hatched nymphs fall to the ground and burrow until they find suitable roots, from which they suck juice. This is the beginning of a 17- or 13-year period of underground existence. Most of the nymphs are 18 to 24 inches beneath the surface.

By spring of the 17th or 13th year the nymphs are fully grown. The transformation to the adult stage of the life cycle is soon to occur. Several weeks before emerging from the ground, the nymphs start burrowing upward. When they have burrowed to about an inch beneath the surface, they stop and await the proper time to continue.