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Scientific name: Magicicada sp.
Common name: 
Periodical Cicada  ("Seventeen Year Locusts")

(Information in this Species Page was compiled by Emily Morse in Biology 220W, Spring 2002, at Penn State New Kensington)

Image the following scenario taking place in Western Pennsylvania:

An adult periodical cicadaIn June, 1985 female cicadas gather in wooded areas filled with the incessant songs of the males. The loudest songs and the largest gatherings of singing males attract the greatest number of receptive females. After mating, the female cicadas use a saw-like appendage (the “ovipositor”) on the end of their pointed abdomens to dig under the bark on limbs of oak or hickory or dogwood trees. Into each of these gashes they lay one or two dozen tiny eggs. Each female then moves on to another limb and then another and another until they each have deposited their six hundred eggs into roughly forty different sites.

By August, the adult cicadas are all dead and gone, and their roaring buzz has faded into a distant memory. The eggs that were not eaten by birds or ants or that were not destroyed by fungi or the summer heat hatch into tiny, ant-sized larvae that fall un-noticed to the ground where they began to burrow six to eighteen inches down into the forest soil. There, among the tree roots whose watery fluids will sustain them, they begin a slow, steady growth and metamorphosis that lasts the next seventeen years.

A periodical cicada nymph It is now April 2002 and these deposited larvae are nearly fully grown. They begin to dig their way back out of their soil home, using their modified front legs.  In May, they are a couple of inches below the soil surface, waiting for  just the right weather to emerge out through their soil turrets and mounds.   Once in the open air they will undergo their final metamorphosis into the short-lived, flying stage of their life cycle.

In June, the rolling, buzzing, and some say, maddening, chorus of the seventeen year cicada will once again fill the woods and suburbs of western Pennsylvania. Those individual cicadas lucky enough (because luck and sheer force of numbers seems to be the principle way that these poorly flying, extremely visible insects survive) to escape the extensive predation by birds (especially crows and grackles), snakes, spiders, skunks, fish, moles and even dogs and cats, will set up, for 2019, another reemergence and another extension of their “magical” cycle of life.

Periodical cicadas of Brood VIII are heard and seen every seventeen years in the woods of Western Pennsylvania during a four or five week period in May and June.  The adults emerge in huge numbers from their soil “nurseries.” They average typically tens to hundreds of thousands of individuals per acre but spectacularly can be found in densities of millions per acre! The male cicadas have a sound producing organ on the ventral side of their rounded abdomens which they use to generate the familiar and inescapable buzzing sound which attracts female cicadas and drives humans of all genders into the relative quiet of their homes. The buzz of a male cicada can reach ninety decibels and has been compared to the roar of a chain saw. The ability to generate noise of this magnitude has earned the periodical cicada the title “world’s loudest insect.”

There are over 1500 described species of cicadas in the world, but only seven of these are classified as “periodical.” The life cycle of a normal, “annual” cicada can span several years and typically includes extensive larval or “immature” stages in which the cicada lives underground feeding on the fluids of tree and other plant roots. In periodical cicadas, though, this life cycle is stretched and expanded to intervals of thirteen or seventeen years! These adult “magical” cicadas (their genus name is Magicicada!), then, spend their allotted month in the open air only after a decade and a half of a dark, subterranean existence.

The adult periodical cicadas have stout, black to brownish colored bodies that are about one and one eighth inches long.  They have two pair of membranous wings that are tipped in orange. The front wings are twice as long as the hind wings and have an open span of about three inches. The head is dominated by a pair of large, bulging, red eyes.

The seven species of periodical cicadas are found exclusively in the eastern United States. Their natural distribution is from the Great Lakes down to the Gulf of Mexico. The three species in the northern portion of this range tend to have seventeen year life cycles while the four species in the southern portion tend to have thirteen year cycles. There is considerable overlap in the ranges of these different types but little potential for interbreeding because of the asynchrony of their adult forms. Within both the northern and southern ranges there are communities of several species that do have their adult emergencies synchronously timed. These communities of cicadas are called broods. There is some controversy as to how many broods there actually are, although most authorities agree that there are at least twelve broods of seventeen year cicadas and thirteen broods of thirteen year cicadas still in existence. A number of broods have died out since their initial descriptions back in the Nineteenth Century. Some new broods have, however, also come into recent existence.

The name “locust” is used in reference to these periodical cicadas. This is an unfortunate, but persistent, mislabeling. “Locust” is an ancient, Biblical name for the grasshopper. The plague of locusts that beset the Egyptians in Exodus describes swarming clouds of voracious plant consuming grasshoppers that can decimate hundreds of square miles of crops and forage. Early settlers in North America seeing the unexpected emergence of the thousands and thousands of cicadas thought that they were observing a plague of Biblical proportions and so named the insect “locust.” In reality, the adult periodical cicada feeds only moderately on plant fluids and alone does very little damage to trees or other vegetation. Limb scarring from egg laying and larvae emergence can open some trees up to infections, but that too is usually without very much serious damage to the productivity or viability of the tree.  Even the larvae, slowly feeding on the fluids within the roots of their host trees do not greatly affect their overall health or rates of growth.



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