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.