Heard, but not often seen, cicadas are insects in the order Hemiptera, suborder Auchenorrhyncha). They 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 various species of swarming 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. They are known to have been eaten in Ancient Greece as well as China, Malaysia, Burma, Latin America, and the Congo. Female cicadas are prized for being meatier. Shells of cicadas are employed in the traditional medicines of China.
Cicadas live underground as nymphs for most of their lives, at depths ranging from about 30 centimetres (0.98 ft) down to 2.5 metres (8.2 ft). The nymphs feed on root juice and have strong front legs for digging.
In the final nymphal instar, they construct an exit tunnel to the surface and emerge. They then moult (shed their skins) on a nearby plant for the last time and emerge as adults. The abandoned exoskeleton remains, still clinging to the bark of trees. V.3 shows two discarded skins.