If Cicadas Come Out Once Every 17 Years, Why Do You See Them Every Summer?

By: Ashley Hamer

These mysterious insects have one of the strangest life cycles in the natural world.

August 01, 2019

In certain parts of North America, you can expect it every summer: the constant, droning buzz of cicadas. But if you hear it every summer, how is it possible that cicadas only come out every 13 years?

One Of These Broods Is Not Like The Other

The periodical variety of the winged insects known as cicadas spend most of their lives underground, sucking sap from tree roots as they slowly grow into adulthood. Finally, after either 13 or 17 years, depending on the breed, the cicadas finish counting the annual blooming of the trees, wait for the soil to warm, and tunnel straight up out of the ground.

But if periodical cicadas only emerge every 13 or 17 years, why do we see them every year? It's because they don't all emerge at once. Cicadas are grouped into roughly 15 broods: 12 broods of 17-year cicadas and three broods of 13-year cicadas. Each of these broods emerge in different years, so residents in cicada regions rarely spend a summer without them. On top of that, many other species of cicada aren't periodical but annual, meaning they emerge every year.

This article first appeared on Curiosity.com.

Next Up

The “Lungs of Our Planet” are Under Threat

World Rainforest Day is June 22, bringing awareness and action to save these precious ecosystems. But if the current rate of deforestation continues, will there be any rainforests in 100 years?

How the World’s Largest Delta Might Slowly Go Under Water

The uneven rise of the sea impacts communities in South Asia

Big Sur Condors, A Conservation Comeback Story

Condors once ranged from Baja California all the way to British Columbia. But, in 1987, the last wild California condor was taken into captivity in order to preserve the species. Now, thanks to a breeding program in central California, the condors are finally returning to their natural habitat in Big Sur.

It’s World Pangolin Day! Meet The World’s Most Trafficked Animal

World Pangolin Day is a yearly global celebration of pangolins and the people working to save them from extinction. This shy curious creature is the most trafficked animal in the world.

Why Islands Have the Most Beautiful and Unique Creatures on Earth

Places like New Zealand, Austrailia, Hawaii, and the Galapagos give us major wanderlust. But what is it about islands that make scientists weak in the knees?

These Bee Chicas Are Colorado’s Local Heroes

Last year, US beekeepers lost almost 40% of their bee colonies. Four women banded together to help the bee population flourish in Colorado.

Nature from Above: The Art of Aerial Photography

I’ll never forget the first time I went up in a small plane. Technical considerations aside, I had a million thoughts going through my mind.

Wombats: The Furry Heroes of the Australian Wildfires

Wombats dug craters which tapped into deep-flowing water, providing vital resources to fauna and fellow animals.

Two Little Penguin Chicks are Hatched at Bronx Zoo

One-month-old chicks join zoo's growing little penguin colony

Oklahoma’s Annual Bison Health Check-up is a Sight to Behold

In Oklahoma, where some of the US’ last remaining tallgrass prairies grow, Native American communities, cowboys and conservations have been working hard to bring back - and maintain - the bison population in the Great Prairies.