Billions of cicadas are invading the U.S. Should Californians be worried?

It is being called the Cicada-pocalypse and the Cicada-geddon.

Over the next few weeks, hundreds of billions, maybe even trillions of cicadas — grasshopper-like insects — will emerge from underground burrows all across the Midwest and the South where they have been living for as long as the past 17 years.

From Wisconsin to Mississippi, Virginia to Oklahoma, immense swarms of the somewhat creepy, red-eyed bugs will carpet trees like little 1-inch extras in a horror movie and generate ear-splitting mating sounds that have been compared to jackhammers and chainsaws. Some have already begun to come out in Georgia and other parts of the South, prompting one North Carolina county to urge the public this week to stop calling 911 asking about the racket.

Should Californians batten down the hatches? Are we in for a cicada onslaught?

Relax, scientists say. In a state marked by earthquakes, bomb cyclones, mega-droughts, fire tornadoes and atmospheric river storms, it turns out that despite having dozens of species of cicadas in the Golden State, their emergence is usually underwhelming.

“We do have cicadas in California. But they are kind of boring,” said Lynn Kimsey, a professor emeritus of entomology at UC Davis. “Our cicadas come out, but they only come out in little dribbles. So we don’t really pay much attention to them.”

And the ear-splitting cacophony associated with the bug-eyed critters’ mating dance?

“They don’t get really noisy. Back East, you almost have to put on noise-canceling headphones if you are outside when they are around,” Kimsey said.

There are at least 3,000 species of cicadas worldwide and about 170 in the United States. California has 80 species, more than any other state. But they aren’t the type that stay underground for 13 to 17 years, emerging in a near-limitless mass all at once. Instead, California’s cicadas come out every year, in smaller numbers. And because not as many emerge at one time, they often go unnoticed by the public.

“They aren’t as loud or obnoxious here,” said Jeffrey Cole, an assistant professor of biology at Pasadena City College. “They are pretty unobtrusive.”

Cole said in the Midwest and South during big cicada years, couples sometimes have to cancel outdoor weddings because the relentless bugs are so loud.

In 2015, he was in Kansas during the emergence of one major cicada brood.

“There were cicadas on the ground,” he said, “cicadas covering buildings, cicadas on every plant and flying around, and there are loud choruses going all day. You can fill a bucket with them, no problem. They are flying in and out of people’s car windows. It’s wild.”

But Californians who are visiting places affected this summer need not worry.

“They are like little six-legged, winged kazoos,” Kimsey said. “There is nothing they can do to hurt you except maybe fly into you. They don’t bite. They don’t carry disease. They have no interest in you. They are just looking for a date. And trying not to get eaten before they find one.”

They live for about one month and are eaten by birds, raccoons, dogs, lizards, squirrels and other animals.

California’s cicadas are the most common type, called “annual” cicadas. The young ones, or nymphs, stay buried about 1 foot underground for roughly 2 to 5 years, drinking the sap from tree roots to stay alive. Some members of each species come out every year.

By contrast, the cicadas involved in this summer’s cicada extravaganza in 16 states are called “periodical” cicadas. They stay buried much longer. There are 15 different groups, called broods, that come out in varying years. Some broods stay buried for 13 years. Others for 17 years.

This year is the first time since 1803 that two prominent broods, the Great Southern Brood and the Northern Illinois Brood, are emerging together.

In some places back East, there will be 1 million cicadas per acre or more, scientists say, potentially sending the population total over 1 trillion.

And the hype is building, just like with America’s last big natural phenomenon, the April 8 total solar eclipse. Parks and museums are running programs. One bakery in Chicago is making cicada-shaped cakes. T-shirts with pictures of cicadas and messages like “Be Loud. Be proud,” “Reunion Tour,” and “I Survived the Cicada Invasion” are selling briskly.

The whole cacophonous curiosity should last through June, scientists say. After the insects mate, and the females lay eggs in tree branches, the newly born nymphs will fall to the ground, start burrowing, and begin the whole cycle again.

Although cicadas are sometimes mistaken for locusts, they do not cause widespread crop damage, and die within a month of coming out of the ground.

Why don’t California and other Western states have any of the “periodical” cicadas that stay underground for 13 to 17 years and emerge in massive hordes?

Nobody knows for sure. One theory is that the kind of deciduous forests that cicadas like to drink sap from are common in the East, rather than the West. Another is that the West is too prone to droughts and that disruptions in water for multiple years would make it hard to stay alive underground for 17 years relying on tree roots for food.

“It’s like asking why we don’t have giant pandas in California,” said Elliott Smeds, a research associate at the California Academy of Sciences who specializes in cicadas.

“The habitat never managed to migrate here,” he added. “There was never a chance for them to colonize California.”

California cicadas can be seen in nearly all parts of the state in late spring and summer, he said. Rural areas like Mount Diablo, the Sierra foothills, or the San Gabriel Mountains are quieter than cities and easier to hear their mating calls. And the sound?

“It’s often that buzzing noise you hear in the middle of a hot day,” said Peter Oboyski, executive director Essig Museum of Entomology at UC Berkeley. “We’ve all heard them probably. They are the background noise of a hot summer day.”

Nobody is certain how billions of cicadas in the Midwest and South all know to come out every 13 to 17 years, all at once. It happens when the soil reaches 64 degrees. How do they tell time so accurately?

“They have internal clocks just like all animals,” Oboyski said. “Our internal clock gets reset every day. But they are going for 17 years without a reset. It is a cellular mechanism. It’s remarkable. Every single step of their lives is really interesting.”