When the eggs hatch, the newly hatched nymphs drop to the ground and burrow. Cicadas live underground as nymphs for most of their lives at depths down to about 2.5 metres (8 ft). Nymphs have strong front legs for digging and excavating chambers in close proximity to roots where they feed on xylem sap. In the process, their bodies and interior of the burrow become coated in anal fluids. In wet habitats, larger species construct mud towers above ground in order to aerate their burrows. 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 exuviae or abandoned exoskeletons remain, still clinging to the bark of the tree.
Most cicadas go through a life cycle that lasts from two to five years. Some species have much longer life cycles, such as the North American genus, Magicicada, which has a number of distinct "broods" that go through either a 17-year or, in some parts of the region, a 13-year life cycle. The long life cycles may have developed as a response to predators, such as the cicada killer wasp and praying mantis. A specialist predator with a shorter life cycle of at least two years could not reliably prey upon the cicadas
Cicadas were revered by Chinese as symbols of rebirth, and kept to enjoy their songs.
