This process is called sublimation. The opposite (deposition) is where a gas turns directly into a solid. Sublimation occurs if the pressure and temperature are right for the specific substance, so that the solid phase in a phase diagram borders the gas phase.
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 world, a 13-year life cycle.
As nymphs, cicadas spend many years living in soil between 2 and 24 inches in depth. Once the cicadas reach the surface, they must find a tree or other vertical surface on which to moult and complete their metamorphosis. After shedding their skins, cicadas are adults and fully capable of flight.