Harvest Fly , a hemipterous insect, of the division homoptera (from having the wing covers of the same texture throughout), of the family cicadadoe, and chiefly of the genus cicada (Oliv.), improperly called locusts in America. It has been known from remote antiquity, and is the of the Greeks, cicada of the Latins, eigale of the French, and cicala of the Italians. The harvest flies or cicadians have short antennae, conical, six-jointed, and tipped with a little bristle ; wings and wing covers in both sexes, inclined at the sides of the body; three joints in the tarsi; a hard skin ; and in the female a piercer lodged in a groove under the end of the body. Those of the genus cicada, which has been improperly translated grasshopper, are easily known by their broad heads; their large, convex, and brilliant eye on each side, and three simple eyes on the crown ; their wings and the covers veined and transparent; and an elevation on the back part of the thorax in the form of an X. The males make a loud rattling sound by means of a kind of kettle-drum apparatus on each side of the base of the abdomen ; this is covered by two large oval plates, and consists of a cavity containing plated folds of a parchment-like membrane, transparent as glass; these are moved by muscular cords, whose alternate and very rapid contractions and relaxations produce a corresponding tension and looseness of the membranes and a consequent harsh rattling noise, heard to a considerable distance; the action is assisted by the rapid movements of the wings, and the sound is rendered more intense by the resonance of cavities within the body protected by valves.
The piercer has two lateral plates toothed like a saw in the lower portion, and between them a spear-pointed borer. They have not the power of leaping like locusts and grasshoppers; the legs are short, and the anterior thighs are armed with two stout spines. In the perfect state they live only a few weeks, performing the work of reproduction and then dying; in the larva state they are wingless and subterranean, living on the juices of roots, and passing a series of years in the ground.
The C. septendecim (Linn.) is called the 17 years locust from the prevalent belief that its life is prolonged to that extent in the imperfect state; undoubted testimony, both from popular and scientific sources, proves that these insects usually appear at intervals of 17 years, but accidental circumstances may accelerate or retard their progress to maturity; though they appear in some parts of the country probably every year, and indeed in all districts except northern New England and to the north of that, the lineal descendants of each swarm appear only every 17 years; the popular name of locust was doubtless derived from this fact of their appearance in large swarms after long intervals of time, like the locusts of the East. In the perfect state this harvest fly is of a black color, the anterior edge and principal veins of its transparent wings and covers being orange red; near the tips of the covers there is a dusky zigzag line in the form of the letter W, which by the superstitious is supposed to indicate approaching war; as the mark on the other wing would be inverted like the letter M, the two were supposed to announce a war with Mexico during their appearance in Louisiana in 1835, which however did not arise until some years after; the eyes are red, with metallic reflections; the rings of the body are edged with dull orange, and the legs are of the same color; the expanse of wings is from 2 1/2 to 3 1/4 in.
Though found upon almost all kinds of trees, except most evergreens, they prefer forests of oaks. The perfect insects emerge from the ground from February to the middle of June, according to latitude and the warmth of the season; their numbers are often so great that the limbs are bent and broken by their weight, from six to eight being sometimes seen on every leaf; the drumming sound is heard from morning to night, but most loudly between the hours of 12 and 2. They are not found in low alluvial lands, and a dry air is necessary for the perfection of the drumming. The males perform the act of reproduction and soon die; they present scarcely a trace of digestive apparatus, and probably take no nourishment; the sexual system is fully developed on emergence from the ground, each of their 500 sperm cells containing about 1,000 spermatozoa. The females have each about 500 eggs, of about 1/30 of an inch in diameter, which when deposited are twice that size; their digestive system is complete, and the demand for food to develop the eggs must be satisfied during their longer life; the females are one third smaller than the males.
In order to deposit her eggs, the female clasps the smallest twig of a tree with her legs, and introduces the piercer to the pith obliquely and in the direction of the fibres, detaching little splinters by the lateral saws at one end to serve as a cover to the perforation; after boring a hole long enough for about 16 eggs, she introduces them in pairs side by side, but separated slightly by woody fibre, and standing obliquely upward; after making a nest and filling it in a space of 15 minutes, she makes others on suitable twigs until her stock is deposited; by this time incessant labor has so weakened her that she drops exhausted from the tree, and soon dies. The eggs are pearl white, very delicate, and are hatched in from three to six weeks, according to favoring circumstances. The twigs pierced by the insect wither and fall to the ground, either on account of the wound or because such are selected as would soon fall from natural causes; in this way many of the larvae reach the earth, but most are developed on the trees; the emerging larva is about 1/16 of an inch long, hairy and grub-like, of a yellowish white color, with six legs, the first of which are strong like lobster claws, and spiny beneath; there are rudiments of wings, or little prominences, on the shoulders, and under the breast is a long sucking ciliated tube with a central tongue.
Active on leaving the egg, they in a few moments drop to the ground, and at once bury themselves beneath the surface by means of their fore feet; they follow the roots of plants, perforating them with their beaks and sucking their juices; they do not descend very deeply into the soil, and change but little during their long subterranean abode except in size and in development of the rudimentary wings. As the time of transformation approaches, they gradually advance toward the surface in cylindrical and circuitous passages, about half an inch in diameter and from a depth of one or two feet; now become pupae, they gradually acquire strength for their final change; they leave the earth in a warm night and ascend trees, on which in a short time the pupa skin bursts on the back, and the perfect cicada comes forth. The ground is sometimes riddled like a honeycomb by their numbers, which in about six weeks are all dead. Did these insects appear every year or two in the same locality, fruit and forest trees would suffer much from their attacks, even though they only rob roots of juices; but fortunately they appear only at long intervals, and their eggs are eaten from the beginning by ants and other insects; the larvae are also devoured by the same insects, by birds (especially woodpeckers), by toads and frogs, and other reptiles; when turned up by the plough, blackbirds and hogs eat great numbers of them; many perish in their wooden prison, and others are killed by the fall from the trees; as they generally occur in swarms containing about the same number at each period, of course only a small proportion of the eggs laid can ever produce the perfect insect, probably not more than two of the deposit of each female arriving at maturity. - Another American species is the dog-day cicada (C. canicularis, Harris), so called from the time of its first appearance on July 25; it is about 1 3/5 in. long, with a spread of 3 in.; it is black above, with a powdery white substance on the under parts, and with green markings on the head, thorax, wing covers, and legs.
These and several other species have the drumming apparatus, which is always in-tegumental, having no relation to the respiratory system; the sound in some of the large southern individuals continues for nearly a minute. Other harvest flies of the same family, but principally of the genus membracis (Fabr.), have only two eyelets; they are not furnished with a musical apparatus, but have the faculty of leaping a distance of 5 or 6 ft.; they are more properly called tree-hoppers. For full details and references in regard to the American cicadadoe, the reader may consult Dr. Harris's work on " Insects Injurious to Vegetation." - The European species do not pass more than a year in their subterranean abode. The C. plebeia (Linn.) is the largest, and is probably the one sung by poets of antiquity, especially by Anacreon and Virgil. These insects were so highly esteemed by the Athenians that they wore golden images of them in their hair; they, however, were also esteemed as food, just before the conclusion of the nymph state; they are said to be sold in South American markets, and, freed from the head, wings, and legs, to be roasted and ground into flour. More than GO species have been described, spread over almost all the warm regions of the earth.
The C. plebeia is black, with reddish spots on the thorax and wing covers. The C. o?')ti, common in central and southern Europe, is about an inch long, yellowish mixed with black; by their wounding certain species of ash tree (ornus), a saccharine fluid escapes, which, dried and hardened, is used in medicine as manna; this hint from the insect has been taken advantage of by man, who, by making incisions in the trees, is able to obtain a large supply of this purgative substance.
Seventeen Years Locust (Cicada septendecim).
European Harvest Flies. - 1. Cicada plebeia. 2. Cicada orni.