Billions Of 17-Year Brood X Cicadas Set To Emerge In NC In 2021

NORTH CAROLINA — Billions of red-eyed cicadas emitting a shrill 100-decibel mating call after spending 17 years gestating underground are about to emerge and could swarm parts of North Carolina.

The Brood X insects — black insects measuring more than an inch long with orange and red wings— have spent their immature years in the soil. But soon they'll scramble to the surface and emerge all at once in a scene that's almost biblical.

There are 15 different types – or broods – of the cicada though, which means a type is emerging somewhere on the east coast almost every year. The last time Brood X emerged in North Carolina was 2004.

They're different from the green cicadas which are present every year, according to Cicada Mania, a site dedicated to "the most amazing insects in the world."

According to North Carolina State Extension, Brood X is one of six broods that emerge in the state. Following this year's emergence, Brood X will not return until 2038.

Here are the five other broods in North Carolina and when you can expect to see them, according to NCSE:

• Brood IXX — emerges in 2024 and 2041
• Brood XIV — emerges in 2025 and 2042
• Brood II — emerges in 2030 and 2047
• Brood VI — emerges in 2034 and 2051
• Brood IX — emerges in 2037 and 2054

The collective song of male cicadas calling for mates can reach up to 100 decibels. Think of a Harley-Davidson motorcycle with straight pipes constantly running outside your window.

The male cicadas are the ones that make all the noise. They do it by vibrating their tymbals, drum-like membranes on their abdomens. They're used to create a mating call, and the noise is so loud because every male is seeking a mate at the same time.

After mating, the females split the bark on living tree trunks, branches and twigs, burrow in and lay between 24 and 48 eggs at a time.

Scientists can't entirely explain the synchronized emergence of periodical cicadas, but one evolutionary hypothesis is that the forced developmental delay was an adaptation to climate cooling during the ice ages.

Matt Troutman, Patch staff, contributed