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.
Live Long and Burrow. When the soil warms up enough, cicadas emerge from the ground, where they've been sucking moisture from tree roots for the past 17 years. They'll shed their exoskeletons, attach themselves to branches, mate and lay eggs before dying off in about six weeks.