Conservation

Brood X: Periodical Cicadas

It's that time again! Every 17 years, periodical cicadas (this ground is known as Brood X) emerge from underground in the late spring. They climb trees, shed the form they held underground, and begin to "sing" their little insect hearts out as they look for mates. The last time we saw these creatures was 2004—back when Brittney Spears was the Queen of Pop and Facebook was just a little app for college students. 

Below, we've compiled a list of FAQs about these small, but noisy, critters. If you have more questions, feel free to reach out to cnc@cincynature.org, follow us on Facebook, Instagram, Twitter, or YouTube, or stop by to learn more about them. They won't be here long -- by the end of June, their babies will be back underground for the next 17 years. 

Want to help scientists studying periodical cicadas map their emergence and learn more about them? Download the Cicada Safari app and help us map Brood X’s emergence! 

 

Cicada FAQ 

What are cicadas? 

Cicadas are insects that belong to the order “Hemiptera.” Hemiptera are unique insects because both their nymph and adult forms contain piercing mouthpartsknown as beaks, which they use to suck fluids out of plantsThis order of insects also includes aphids, leafhoppers, and shield bugs.  

 

Are cicadas dangerous to humans? 

No. Cicadas cannot sting or bite and pose no threat to humans or other animals. 

 

Why are they so noisy? 

Male cicadas have a drum-like organ in their abdomen called a “tymbal.” Small muscles rapidly pull the tymbal in and out of shape. The cicadas mostly hollow abdomen helps to amplify this sound. Male cicadas make noise to establish territory and attract females. Females and some male cicadas will also flick their wings to make a sound, but this is less common.  

Unlike most other insects, cicadas typically sing during the day. Their singing can reach 90 decibels, which is about the same as a lawnmower! 

 

What are “periodical” cicadas? 

Periodical cicadas spend their lives underground and emerge either every 13 years or every 17 years. This is different from annual cicadas, which emerge every year. Annual cicadas can be found around the world. Periodical cicadas, however, are unique to North America.  

Periodical cicadas are known for their black bodies, clear wings, and big red eyes, whereas annual cicadas are green and black. 

 

Why are there so many of them? 

Cicadas are eaten by just about everything. For periodical cicadas, having a population size that numbers in the billions, possibly even trillions (as many as 1.5 million cicadas per acre in some areas!)makes them much less impacted by predation. This helps ensure reproduction and continuation of the species.  

 

What do cicadas eat? 

Cicadas eat xylem, the fluids contained within plants. This makes up both their food and water source. They use their beaks to suck these fluids out of the plants.  

 

Where are periodical cicadas in between their emergences? 

Periodical cicadas spend their time underground feeding on the fluids in tree roots between their emergences. Contrary to popular belief, they do not hibernate during this time.  

 

Why do they stay underground for 17 years? 

Scientists still have a lot of unanswered questions when it comes to periodical cicadas, but it is believed that this timed emergence helps with predation. Most insectivores do not live for 17 years, so waiting this long to emerge from hiding means that no predators have evolved to feed specifically on cicadas. 

 

What is “Brood X”? 

“Brood X (pronounced “brood ten”) is also known as the “Great Eastern Brood.” It is a brood of periodical cicadas that emerges every 17 years. Their last emergence was in 2004, and their next emergence will be this spring and summer (2021). 

 

Where will Brood X emerge? 

Brood X’s emergence will span up to 15 states, including Ohio, Delaware, Georgia, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, New York, North Carolina, Pennsylvania, Tennessee, Virginia and West Virginia. 

While each brood has their own distinct range, periodical cicadas as a whole are exclusively found in the eastern and midwestern United States.  

 

When will Brood X emerge? 

Brood X will emerge when the soil temperature 8 inches below ground reaches 64 degrees. This is typically sometime in mid-May, but can be earlier or later depending on the weatherThey will likely be around until late June or early July.   

 

Will cicadas harm my plants? 

Generally speaking, no. Many people confuse cicadas with locusts, which actually can cause significant harm to crops, trees, and shrubs alike. However, mature trees and shrubs typically withstand no harm from cicadas. 

The only exception to this can be young, immature trees. Their branches can be damaged by female cicadas laying their eggs in them. If this is a concern for you, wrapping your young trees in mesh netting with holes under ¼” wide until the cicada emergence has ended can provide protection.  If you are hoping to plant trees, it is a good idea to wait until July when the emergence has ended, so as not to risk harming a young tree.  

Flowers, crops, and other garden plants are not typically affected by cicadas, as their stems are not sturdy enough to support their eggs. Click here for more information. 

 

What are cicadas good for? 

Cicadas are a valuable part of our ecosystem. They provide a food source for just about anything that eats insectsAdditionally, they prune mature trees, help aerate the soil, and return nitrogen back to the soil when they die and decompose. 

 

Can you eat cicadas? 

While there are a number of weird and wonderful cicada recipes out there, it is not recommended that you eat cicadas. Their populations are fragile and eating them only contributes to declining numbers.  

 

What are the different stages in a cicada’s life cycle? 

Adult female cicadas use their ovipositor (a tube-like organ used for laying eggs) to cut a slit in a tree limb. They lay their tiny, rice-shaped eggs in this slit. Upon hatching from their eggs, young cicadas feed on the surrounding tree fluids. When they are ready, they climb out of their tree branch and dig a hole underground. Here, they begin to feed on the fluids in tree roots. They will spend many years being active undergroundA few days prior to their emergence, the cicadas eyes will change from white to their signature orange or red. 

After 17 long years, the cicadas will create tunnels which allow them to emerge from the ground. Once they crawl from their tunnels in their nymph form, they will seek out a nearby vertical service, like a plant or a fence, and begin to shed their exoskeleton. Their adult skin will harden and their wings will inflate with fluid. In no time at all, they are a fully formed adult cicada. For all of this effort, adult cicadas live an extremely brief life. Their sole purpose during their adult life is to reproduce.   

 

What can we do to help conserve cicada populations? 

As cicadas spend many years just below the surface of the ground, they are extremely susceptible to sprays and pesticides that are applied to lawns. Foregoing the use of these things, or using less of them, can be hugely beneficial to cicadas.  

Habitat loss is another threat to cicadas. As trees are cut down, cicadas not only lose their food source, but also the eggs that may have been laid in that trees’ branches. Planting new trees and shrubs, and leaving existing trees and shrubs intact, is one of the most effective ways to help cicadas thrive.