Cicada Sagas: After 17 Years Brood X is Back

 

Cicada Sagas: After 17 Years Brood X is Back

Written by Kristine Manganelli (Somerset County 4-H Coordinator)

Adult Cicada

Adult Cicada

I have distinct childhood memories of being kept awake by the constant, droning noise of cicadas during hot summer nights with the windows open. Get ready to welcome this ridiculously loud invertebrate back into your lives because we only have a few short weeks of peace until billions of cicadas join us here above ground. It has been relatively quiet these past 17 years, but they’ve been underground all along, just waiting for the right time to emerge.

Cicadas are insects that belong to the order Hemiptera, including stink bugs, bed bugs, and aphids. In their adult stage, they can reach almost 3 inches in length! There are annual cicadas which appear every year and periodical cicadas which live out a majority of their lives underground in broods (groups of cicadas that share an emergence year). The broods emerge regularly on a cycle lasting anywhere from 13 to 17 years!

While there are 3,000 species of cicadas found worldwide, periodical cicadas are unique to North America, found only in the central and eastern regions of the United States. So, we are lucky to experience periodical cicadas here in New Jersey, despite their volume!

As brood cycles overlap, there are cicadas every summer, but 2021 marks the return of Brood X. Brood X is the largest of the 17-year cicada broods, occurring in parts of 15 states including New Jersey. Broods are identified using Roman numerals, so Brood X stands for Brood 10. Brood I was established by entomologist Charles Marlatt in 1893 while working for the Department of Agriculture.

Both types are fascinating as they come out of the ground in sync when the soil temperatures reach 65 degrees Fahrenheit. This is due to begin next week in southern states, but won’t happen in New Jersey until sometime in mid to late May. Once above ground, the sole purpose of a cicada is to mate. Hence, the vocalization that they are famous for.

Believe it or not, we are only hearing about half of the cicadas at a time, despite all of that racket because only male cicadas sing! They gather in trees and bushes, singing together in chorus to amplify their voices and attract female mates. Cicadas can be as loud as a rock concert, upwards of 100 decibels! They produce this species-specific sound using vibrating membranes called tymbals located on both sides of the abdomen. To create cicada song, the tymbals contract 300-400 times per second and the sound created is intensified by a hollow abdomen. Although these sounds may all seem alike, they have different calls to express different messages such as danger or alarm.

Cicadas go through a 3 stage life cycle, starting as eggs, hatching into nymphs, and growing into adults. After mating females will lay up to 400 eggs spread out among many sites on twigs or branches. After 6-10 weeks, the eggs hatch into nymphs which burrow themselves into the ground where they will live by sucking the water from plant roots. They will continue to develop underground for up to 17 years, until the time comes for the next cycle to begin.

Nymph cicadas will emerge and molt their shells above ground in their final step in the transformation to becoming adults. When their molted shells begin appearing outside, it is a sign that emergence has begun. After molting, the white body and shriveled wings will harden. Once it reaches full maturity, it will have a black body, red eyes, and orange-tinged wings.

Molted cicada shell

Cicadas emerge in large hordes as a means of survival. The sheer number overwhelms predators to the point of satiation. It is basically impossible for cicada predators to eat all of them. As many as 1.5 million cicadas can occupy a single acre! Therefore, the cicadas are able to successfully reproduce. Adult cicadas will die off anywhere from 4-6 weeks after emerging.

Although the mobs of screaming cicadas might be very annoying, they are not pests so using pesticides to control them will not be successful. In fact, cicadas are an extremely important part of our local ecology. As billions of cicadas emerge from the ground they will aerate the soil on their way out. They will then provide a feast for a myriad of wildlife including birds, snakes, turtles, and mice to name a few. In the end their billions of bodies will add an abundance of composted nutrients to the ground and forest floors. Cicada bodies contain 10% nitrogen, more than the typical amount found in dead leaves and other common debris.

There goes Mother Nature, reminding us once again of the interconnectedness that exists in nature. Even a bug that spends 17 years underground just to die a few weeks after emerging, plays an integral role in the ecosystem. Scroll down to learn how you can also play an important role by locating cicadas in your area and sharing data with citizens and scientists from all over the eastern United States.

Get OUTSIDE

Contribute scientific data as a citizen scientist by downloading the free Cicada Safari app developed by professor and cicada expert Dr. Gene Kritsky, working with the Center for IT Engagement at Mount St. Joseph University in Cincinnati, Ohio. Spend time outdoors this Spring and Summer while contributing to science! When you see a cicada, snap a photo and submit via the app to add your sighting to a live map. This will help researchers monitor cicada species diversity as well as the relationships broods have with each other. Don’t be scared to get close enough for a picture; cicadas are really big, weird-looking insects, but they are completely harmless. Cicadas do not sting or bite humans. Always remember, we respect wildlife by looking and not touching, although a discarded shell is fair game.

The Cicada Safari app also provides educational information, as well as identification techniques.

Sources:

 
Somerset County 4-H