Why are the trees buzzing? Get the skinny on Southern Utah cicadas

ST. GEORGE — The trees are alive with the sound of buzzing. A chorus of unique insects calls out to potential mates and fills the air with noisy whirring.

A cicada on a tree in Southern Utah, Parowan, Utah, date not specified | Photo by Alysha Lundgren, St. George News

The cicada’s unique sound is created when males vibrate a noise-making organ on their bodies called tymbals, according to Cicada Mania. Cicadas are capable of making a variety of sounds with these organs, including the characteristic buzzing associated with the insect’s mating calls.

Samual Wells, an assistant biology professor at Southern Utah University, said that while most species of cicada use tymbals to create their song, others also crepitate, which is when the insects use their bodies to produce clicking noises.

According to a Facebook post by Zion National Park, some cicadas, like those in the genus Platypedia, lack tymbals and can only use their wings to produce crackling sounds. Similar to how a metal dog-training clicker works, the insects bend the semirigid surface of their wings to create a snapping sound.

Crepitating cicadas can be found in the park’s higher elevations, in Kolob Canyons and along Kolob Terrace Road, according to the post.

Wells said that because multiple species may be present in an area, the insects develop different calls to avoid attracting mates of another species. For instance, in one California location, five species occur together, each with its own song.

A cicada on a tree in Southern Utah, St. George, Utah, date not specified | Photo by Alysha Lundgren, St. George News

“This … has been a good year for cicadas,” he said. “Many species have emerged in Utah and, of course, their calls can be overpowering.”

The primary reason the insects have different songs is that groups don’t always emerge at the same time; cicadas developed different sounds as they evolved.

“(Cicada sound-making) body parts don’t change very quickly over evolutionary time but the timing and amplitude of the calls are more flexible and can change quickly.”

Wells said there are more species of cicada in the West than in the eastern U.S., but they are “often quite different.” The famous cicadas, well-known for emerging every 13-17 years, are not present in Utah, but the state is home to more than a dozen other species, some of which might remain undescribed.

In Utah, cicadas most commonly belong to the genus Okanagana, which is known for its black and orange color patterns. These insects typically have a two- to five-year cycle that is based on accumulated rainfall. Cicadas have precise internal “rain clocks” that allow them to emerge simultaneously, Wells said.

Those who “miss the cue,” also risk not finding a mate, Wells said.

A cicada on a tree in Southern Utah, St. George, Utah, date not specified | Photo by Alysha Lundgren, St. George News

When cicadas emerge from the ground, they leave groups of holes that are bigger than those created by most wasps and spiders. Wells said these holes might be dime-sized. The pits are unique in that they are often unsymmetrical, as the insects simply push through the ground.

To feed, cicada nymphs use piercing-sucking mouth parts, many times stronger than those belonging to mosquitoes, to drill through a tree’s roots and into its vascular tissues to drink the plant’s fluids. Once in place, they can stay put for months or years at a time, Wells said.

Cicadas only dig out of the earth to find mates, St. George News previously reported. They climb trees, where they shed their exoskeleton and leave it clinging to the bark. There, it may startle passersby, but fear not, these insects reportedly are harmless.

“Cicadas are a fun group — and a noisy one at times,” Wells said.

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