Like people in a pandemic winter, periodical cicadas are waiting for the warmer weather of spring.

What's happening: In a few weeks, billions of the insects are predicted to emerge in parts of the eastern U.S. after 17 years — and the vast majority of their life — underground.

Brood X is one of the largest of 15 groups of cicadas that come out en masse in the U.S. at different time intervals — some every 13 years, others every 17, and in rarer alignments, at the same time.

• Periodical cicadas (Magicicada) make an appearance most years. (And the adults of annual cicadas, which have a two-year life cycle, emerge every year to reproduce.)

What to expect: Once the soil temperature reaches 64°F, typically in late April or early May, billions of noisy, red-eyed, black-bodied cicadas will emerge in Pennsylvania, Tennessee, Indiana and several spots in between.

• They'll then make a bunch of noise, mate and lay their eggs in trees — all within four to six weeks.
• Those cicadas will die and their nymphs will fall to the ground, bury in to feed on tree roots, and the cicada cycle starts again.

What's next: Who knows what the future holds — and, as Vox's Brian Resnick notes, how cicadas even know when it has arrived — but set your clocks: Brood X will be back in 2038.