Brood XIV Is Back for the 2nd Time This Century

The cicadas of Brood XIV are back for their second 21st-century appearance, making a noisy sweep across 15 states. These large insects, noted for their deafening chorus and sheer numbers—about 1.5 million per tree-covered acre—have begun emerging in Tennessee and North Carolina, with billions more expected across the Southeast through mid-June. Time takes a look at how they operate and why they're counterintuitively more of a boon than a nuisance.

• Timing: Brood XIV—initially recorded by Plymouth Colony's William Bradford in 1634—is just one of 15 periodical cicada groups in the US that emerge at either 13- or 17-year intervals. Each brood emerges in distinct regions (see a Brood XIV map here and a map showing all the broods here), with adults exiting the underground once soil temperatures hit 64 degrees Fahrenheit. They'll survive for about six weeks, during which time the females will make tiny cuts in tree branches to insert their eggs.
• The life cycle: Those eggs will hatch into nymphs within 10 weeks, cascade to the ground, burrow, attach to a rootlet, and suck out the nutrition they need until their next emergence.

• Not that bad: While their decomposing bodies can create an unpleasant odor, cicadas don't swarm, bite, or spread disease, and the damage they cause is limited to the possibility of minor damage to young tree branches from egg-laying. Cicadas help the environment by aerating soil, providing food for wildlife ("They act almost like Snickers bars of the forest," entomologist Dr. John Wallace colorfully tells FOX43), and recycling nutrients into the ecosystem after they die.
• Trivia tidbit: Vox points out that periodical cicadas exist nowhere else on the planet besides eastern North America.