cicada on a leaf

Brood X cicadas: 2021 the 17-year emergence

Godfrey Nalyanya, Ph.D.

The Brood X cicada — red-eyed and louder than a lawnmower. Their massive 2021 emergence will be taking place across 15 Midwest and Mid-Atlantic states this spring in May through June or, as soon as the soil temperature rises to approximately 64 degrees Fahrenheit. 

Compared to the last Brood X emergence 17 years ago, experts predict this year’s to be one of the largest in history with estimates of over one billion individual cicadas surfacing. So what should the residents or visitors of these states expect to see and hear? More importantly, is there any risk associated with this mass emergence?

Read on to find out more information about these unique and mysterious creatures.

What you should know about Brood X cicadas

What makes Brood X cicadas different from other cicadas? 

There are two kinds of cicadas, annual and periodical. Brood X cicadas are periodical. This specific brood emerges every 17 years, whereas annual cicadas emerge once a year. Additionally, annual cicadas are greenish in color and fast moving, whereas periodical cicadas have black bodies, red eyes, and tend to be sluggish.

Which states will Brood X cicadas emerge from in 2021?

Fifteen Midwest and Mid-Atlantic states will experience some level of cicada activity, although some states will see and hear more than others. According to The National Wildlife Federation, these include New York, Pennsylvania, New Jersey, Delaware, Maryland, West Virginia, Virginia, North Carolina, Georgia, Tennessee, Ohio, Kentucky, Indiana, Illinois, and Michigan. Maryland is believed to be an epicenter for activity.

Do cicadas bite or carry diseases?

Cicadas, although somewhat frightening-looking with their red eyes and three-inch wingspan, are completely harmless to people and animals. They do not bite, sting or carry diseases.

What if my pet eats a cicada? Are they toxic?

Cicadas become snacks for all sorts of animals. If your dog or cat eats one, they should be fine. If they eat too many cicadas, they may get an upset stomach or diarrhea, but cicadas are not toxic.

What do cicadas eat?

While living underground, the nymphs will feed on sap from tree roots. Once they emerge from the ground, they’ll shed their skin on trees and become winged adults. They will then fly up into trees to feed on shoot sap, a food source that is plentiful in the spring as trees begin growing new shoots and leaves.

Are cicadas harmful to trees and plants?

Cicadas are little threat to mature trees. However, saplings and young trees are at risk. A female cicada will lay as many as 600 eggs in living twigs. And, because of the sheer numbers of periodical cicadas, heavy egg-laying may result in twig die-off or ‘flagging’ in young branches. To protect young trees or saplings, cover them with fine netting or cheesecloth to avoid any damage.

Are cicadas harmful to structures? 

Brood-X are not harmful to structures and will not seek shelter inside your home, although they may accidentally enter your home if your doors or windows are left open. 

What time of day are cicadas less active?

Cicadas are most active in the daytime when the temperatures are warm. Unfortunately, this is also when people are most active, too. Therefore, if you’re looking for a good time to avoid them, try in the evening or early morning hours when temperatures are cool and they remain perched in trees.

What does a Brood X cicada look like?

A little frightening looking with their black bodies and red, beady eyes, the Brood-X cicadas measure approximately 1- to 2-inches long and have a 3-inch wingspan.

Why do cicadas make so much noise?

The male cicadas are the noisy ones – producing nearly 100 decibels of sound. Multiply that by hundreds of thousands and even millions, and you have a chorus of cicadas all hoping to attract a female mate. This deafening noise is produced by the males vibrating their tymbal, a membrane located on their abdomen. In addition to using this high-pitched noise to attract females, it is believed that they also may use it to deter predators.

How long do cicadas live?

This is an especially important question, as residents in some of the more active states can’t wait for the noise to come to a halt. Once the nymphs emerge from the ground and become adults, they will live for approximately 2-4 weeks.

Why do Brood X cicadas stay under the ground for 17 years?

It is thought that this species stays underground for such a lengthy amount of time to avoid predators. If a predator cannot predict when the cicadas will emerge from the ground, their chance for survival increases exponentially. Despite some being eaten once emerged, the greater majority will survive long enough to mate and lay eggs. 

What is their life cycle? 

After mating, adult females lay their eggs in twigs. After about 10 weeks, the eggs hatch into nymphs. The nymphs bury themselves about 18 inches in the ground for the next 17 years, where they will feed on sap from tree roots. When soil temperatures on the emergence year reach about 64 degrees Fahrenheit, the cicadas will emerge from the ground as nymphs. These nymphs climb on the first thing they can find where they will then molt into a soft-bodied white-winged adult. Their soft exoskeleton will harden in about 6 days. 

The adult stage lasts 2-4 weeks. The adult males call to attract females using their tymbal. Once the female mates, she’ll lay her eggs in twigs. When the mating and egg laying ritual is complete, the adults will fall to the ground where they will provide nutrients for animals and the soil. It’ll be 2038 before Brood X will see the light of day again and the cycle will continue every 17 years.

Should I apply pesticides to prevent cicadas?

Cicadas are harmless insects. Other than being a nuisance, they provide nutrients for all types of animals, help aerate the soil, and cause little to no damage to buildings, trees, and plants. Applying a pesticide would cause more harm than good. As annoying as they may be, after a few short weeks, they’ll be gone.

For press inquiries about Brood-X Cicadas, contact [email protected].

Godfrey Nalyanya, Ph.D.
Godfrey Nalyanya, Ph.D.

Godfrey Nalyanya, Ph.D. is the Regional Technical Services Manager and Entomologist for Rentokil North America, overseeing several states in the Northeast U.S. As an expert in urban integrated pest management, Godfrey is primarily responsible for maintaining and enhancing service quality through training. He also troubleshoots and resolves unique pest challenges in accounts, conducts quality assurance reviews, and performs new product evaluations and testing. He holds a Bachelor’s Degree in Biological Sciences from Egerton University (Njoro, Kenya), and his Masters of Science and Ph.D. in Entomology from North Carolina State University. He is an active member of the Entomological Society of America and Maryland Pest Control Association.

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