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.
Having spent most of their 17-year-old lives underground, billions of Brood II Magicicada cicadas are emerging throughout the mid-Atlantic states for a few weeks of noise-making, mating, and egg-laying. Though their time aboveground will be brief, around four to six weeks, they'll surely make their presence known.