A cicada (play /sɪˈkeɪdə/ or /sɪˈkɑːdə/) is an insect of the order Hemiptera, suborder Auchenorrhyncha (which was formerly included in the now invalid order Homoptera), in the superfamily Cicadoidea, with large eyes wide apart on the head and usually transparent, well-veined wings. There are about 2,500 species of cicada around the world, and many of them remain unclassified. Cicadas live in temperate to tropical climates where they are among the most widely recognized of all insects, mainly due to their large size and unique sound. Cicadas are often colloquially called locusts, although they are unrelated to true locusts, which are a kind of grasshopper. Cicadas are related to leafhoppers and spittlebugs.
Cicadas are benign to humans under normal circumstances and do not bite or sting in a true sense, but may mistake a person's arm or other part of their body for a tree or plant limb and attempt to feed. Cicadas have a long proboscis under their head which they insert into plant stems in order to feed on sap. It can be painful if they attempt to pierce a person's skin with it, but it is unlikely to cause other harm. It is unlikely to be a defensive reaction and is a rare occurrence. It usually only happens when they are allowed to rest on a person's body for an extended amount of time.
Cicadas can cause damage to several cultivated crops, shrubs, and trees, mainly in the form of scarring left on tree branches while the females lay their eggs deep in branches. Many people around the world regularly eat cicadas though the female is prized for being meatier. Cicadas have also been known to be eaten in Ancient Greece, China, Malaysia, Burma, Latin America, and the Congo. Shells of cicadas are employed in the traditional medicines of China. Look up cicada in Wiktionary, the free dictionary.
The name is a direct derivation of the Latin cicada, meaning "tree cricket". There is no word of proper English, or indeed Germanic, etymology for the insect. In classical Greek, it was called a tettix, and in modern Greek tzitzikas—both names being onomatopoeic.