1911 Encyclopædia Britannica/Cicada

CICADA (Cicadidae), insects of the homopterous division of the Hemiptera, generally of large size, with the femora of the anterior legs toothed below, two pairs of large clear wings, and prominent compound eyes. Cicadas are chiefly remarkable for the shrill song of the males, which in some cases may be heard in concert at a distance of a quarter of a mile or more. The vocal organs, of which there is a pair in the thorax, protected by an opercular plate, are quite unlike the sounding organs of other insects. Each consists in essence of a tightly stretched membrane or drum which is thrown into a state of rapid vibration by a powerful muscle attached to its inner surface and passing thence downwards to the floor of the thoracic cavity. Although no auditory organs have been found in the females, the song of the males is believed to serve as a sexual call. Cicadas are also noteworthy for their longevity, which so far as is known surpasses that of all other insects. By means of a saw-like ovipositor the female lays her eggs in the branches of trees. Upon hatching, the young, which differ from the adult in possessing long antennae and a pair of powerful fossorial anterior legs, fall to the ground, burrow below the surface, and spend a prolonged subterranean larval existence feeding upon the roots of vegetation. After many years the larva is transformed into the pupa or nymph, which is distinguishable principally by the shortness of its antennae and the presence of wing pads. After a brief existence the pupa emerges from the ground, and, holding on to a plant stem by means of its powerful front legs, sets free the perfect insect through a slit along the median dorsal line of the thorax. In some cases the pupa upon emerging constructs a chimney of soil, the use of which is not known. In one of the best-known species, Cicada septemdecim, from North America, the life-cycle is said to extend over seventeen years. Cicadas are particularly abundant in the tropics, where the largest forms are found. They also occur in temperate countries, and were well known to the ancient Greeks and Romans. One species only is found in England, where it is restricted to the southern counties but is an insect not commonly met with.