CICADA (Cicadidae), insects of the homopterous division of the Hemiptera (q.v.), generally of large size with the femora of the fore legs spined below, two pairs of large membranous wings and prominent eyes. Cicadas are remarkable for the shrill noise emitted by the males, which has been variously compared to a knife-grinder, scissors-grinder or even a railway whistle, and may be heard in concert at a distance of a quarter of a mile or more. The sound-producing organs are a kind of drum on each side of the base of the abdomen. These drums vibrate by the action of power ful muscles and the sound can be modified by the so-called mirrors or sounding boards. Although no auditory organs are known in the females, the song of the males is regarded as a sexual call.
One of the best-known species is the periodical cicada (Tibicina septendecim) of N. America, often known as the 17-year "locust" which appears in great numbers after long intervals. Its peri odical appearance is due to the nymphs requiring often as long as 17 years for their development, and to the fact that the adults of one generation appear about the same time in vast numbers. By means of a saw-like instrument the eggs are laid in the twigs of trees, and the nymphs, upon hatching, drop to the ground, where they bury themselves. They feed by sucking juices from the roots of forest and fruit trees and finally change into the so-called "pupae." In the latter stage the insect crawls from the ground and, grasping a suitable support, allows of the emergence of the fully-fledged cicada. In some cases these "pupae" construct curi ous earthen chimneys wherein they live before turning into adults. The life-histories of cicadas are all very similar, but few are so long-lived as the species alluded to. Over i,000 kinds are known and they are most abundant in the tropics. One species occurs in the southern counties of England, but is rare ; 74 species are known in the United States. See J. G. Myers, Insect Singers: a Natural History of the Cicadas (1929).