Insect identification > Homoptera > Periodical cicada

Periodical cicada


The periodical cicada or 17-year locust (Magicicada (Tibicina) septendecim L.). - This remarkable insect is a native of North America. It is found from Vermont and Massachusetts to northern Florida and west to Wisconsin, Iowa, Kansas, (Colorado?) Oklahoma and Texas but is not of great importance near its northern limits.

The adult is about an inch long, with a stout black body, orange eyes, legs and wing veins. The wings when at rest extend con­siderably behind the body. In the far South it appears early in May while near its northern limits it may be as late as early June.

The insects are usually in evidence for 5 or 6 weeks and are particularly noticeable in and near wooded areas. They suck the sap from various trees but do little injury in this way. The females lay their eggs in the smaller twigs of trees, shrubs and even in herbaceous plants, the oak and hickory, and in the case of fruit trees the apple seeming to be preferred for this purpose, though more than 75 kinds of trees are attached.

The eggs are placed in slits made in rows by the ovipositor and a twig thus punctured is liable to break off either entirely or in part. The eggs hatch in 6 or 7 weeks and the nymphs drop to the ground and burrow to the roots where they feed until the seventeenth spring from the one when they entered the ground, most of them being between 6 and 18 in. below the surface.
During the seventeenth spring the nymphs burrow upward nearly to the surface of the ground but do not usually come out until ready for the final molt producing the adult.

In some cases, however, upon reaching the surface they construct earthen cones or chimneys sometimes six or eight inches high, within which the burrow is continued. It is supposed that these are constructed where the cicadas are in moist places and these structures will bring the insects out above the moisture, or that a shallow soil enables them to reach the surface before the normal time, or unusually warm conditions hasten their start, and on their arrival they are not ready for their final molt. Recent work indicates that length of day is a factor. Probably the last word on this subject has not yet been said.

Arrived at the surface of the ground and ready to molt for the last time, the nymphs crawl out of their burrows, the greater number of them in the afternoon and evening, and make their way to any objects such as a tree, stick or anything at hand and on these molt for the last time and become the adults which are ready for flight the next morning.

In the course of nearly 17 years of underground feeding it is only natural that some finding an abundant food supply should be able to gain a little time and appear during the sixteenth year as "forerunners" of the main brood, and that others with scanty food should be delayed until the eighteenth season. These are few in number, however. In the South is a race with a 13-year life, the origin of which as related to the other race is not as yet explained.

Though a cicada's life is (except for the race just mentioned) 17 years, they occur in one place or another every year, showing that in some way in the past these insects have diverged so that there are now 17 broods. Some places are so unfortunate as to have several of these broods but, though the cicada may appear there every 4 or 5 years, the descendants of any one of these will not be found until 17 years have elapsed.

Numerous enemies of the periodical cicada are known, many of them being parasites. Some birds feed on them and a fungus causes disease of the adults. Various mammals feed on them as they are coming out of the ground.

Cicada Control. - In forests nothing can be done to control these insects; but when they appear in sufficient numbers in parks and orchards to make treatment desirable, certain methods for preventing injury or for the destruction of the insects are feasible. In some cases, collection of adults by hand has paid. In others, spraying the treetrunks and other objects on which they rest while molting after leaving the ground, aiming to hit as many of the insects as possible, has proved quite effective, for where the cicadas are not killed they are crippled by the action of the particles of the spray which strike them.

This treatment, however, to be successful must be repeated every evening about sunset or very early in the morning, before the insects begin to fly, as long as they continue to come out of the ground.

In the case of fruit trees anywhere, pruning is not advisable, if spring cicadas are due in that locality, until after the eggs are laid. Then, pruning and burning the punctured twigs before the eggs hatch are desirable. In some cases young trees suffer so severely that it is not advisable to set out nursery stock the year before cicadas are due. Apple "whips," however, can usually be safely planted the same spring that the cicadas come, being generally too small to suffer much by the attacks of these insects. Hogs allowed to run under trees known to have cicadas at their roots will kill many of these pests as they come to the surface to become adult in May and June of their seventeenth year.

Various species of cicadas are common in nearly all parts of the United States. In the East the dog-day cicadas (Tibicen linnei Sm. & Grsb., and others) are often noticeable, singing in the trees during late July and August. Most of these species are somewhat larger than the periodical cicada and generally black and olive green, with a white powder or "bloom" on the underside of the body.

They are supposed to have about a 2-year life history and, as individuals occur every year, two distinct broods. A few of these species greatly resemble the periodical cicada in color but are smaller, and, as they appear more than a month after the latter have disappeared, no confusion should lead to the belief that the periodical cicada has appeared at that season.