In April 2024, the cicadas are starting to buzz. Reports of cicada broods emerging in the South of the U.S. are underway. The insect’s signature high-pitched and alarming sound has already led some people to call law enforcement in South Carolina to report a siren-like noise. However, that noise is not a siren, but periodical cicadas.
These cicadas, broods XIX and XII, emerge in cycles of 13 to 17 years. It’s estimated that in 2024, trillions of cicadas will emerge from different states in the Southern U.S. and the Midwest. Although, they won’t all surface at the same time. Here’s all you need to know about the cicadas and their long-awaited emergence.
Why the Cicada Emergence Is Happening
(Credit: Jamie Noguchi/Shutterstock)
The reason why the cicada emergence is happening is because two cicada broods — a 13-year-old brood called Brood XIX (The Great Southern Brood) and a 17-year-old brood called Brood XII (The Great Northern Illinois Brood) — are coming back at the same time. This happens every 221 years.
These broods will not only emerge simultaneously but will also intermingle with each other despite differing life cycles. Since 13-year and 17-year-old broods emerge every 5 to 6 years during the same year, they don’t usually have any contact with each other.
The last time 13 and 17-year periodical cicada broods crawled from the ground was in 1998, and the last time they emerged together was in 1803.
The Life Cycles of Cicada Broods
(Credit: Rik Oggioni/Shutterstock)
Periodical cicada broods are cyclical. They have the longest life cycle for insects. Once one hatches from an egg, it will spend 17 years underground, eating and tunneling. The small insects suck on plant roots and grow from about the size of an ant to almost the size of a full-grown cicada. Some experts suspect cicadas spend most of their lives underground to avoid predators.
But when the cicadas reach the surface, they only live for a few weeks. During this time, they will mate and lay eggs, and the nearly two-decade-long cycle will start again.
Aside from these groups, some cicadas that are not part of them might emerge, too. These are called off-cycle cicadas or stragglers, and climate changes might cause them.
During May or late April of the 13th or 17th year, the baby cicadas emerge at dusk and crawl up trees, fences, weeds, and poles to shed into their final form. Like their recently hatched forms, the newly molted adult cicadas are soft and cream-colored. After some time passes, their light-colored bodies darken, and their wings turn orange. Then, the winged creatures are ready to fly off into the night.
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When Will the Emergence Start?
(Credit: Gerry Bishop/Shutterstock)
The cicada emergence will begin in late spring or early summer. The insects are reliant on soil temperatures because when the ground temperature reaches 64 °F (18 °C), they know it is time to reach the surface.
This is why cicadas emerge in the South before they do in more northern states. Researchers suspect the insects have an internal clock that takes cues from their environment to know that it has been 17 years.
Where Will the Cicadas Emerge?
(Credit: M.A. Kleen/Shutterstock)
Cicadas are found primarily in Eastern, Midwestern, and Southern parts of the U.S., specifically where trees and shrubs are abundant. The broods are within these ranges.
The Northern Illinois Brood
This brood includes three types of cicadas. They are the Magicicada cassini, Magicicada septendecim, and Magicicada septendecula. Illinois will have cicadas emerging from both the 13-year and 17-year broods.
The Great Southern Brood
As the most enormous brood, the southern brood will stretch across Maryland to Georgia, to the Midwest’s Iowa and Oklahoma. They also have been seen as far north as Illinois. The cicada species in this 13-year brood include the Magicicada neotredecim, Magicicada tredecim, Magicicada tredecassini, and Magicicada tredecula.
Read More: The Emergence of Brood X Cicadas
The Sound of the Cicadas
Male cicadas are the loudest, with distinct songs. The first one is called a congregational song that is influenced by the weather and other chorusing males. This song establishes insect territory and attracts mates. The males also have a particular love-making song they play before they mate with a lady cicada.
The sounds might be loud to ward off predators and the loudest of all the cicadas (nature’s sirens) are periodical cicadas, or the ones emerging this year. However, this might be because of the number of males competing all at once, like a screaming competition.
Female cicadas don’t produce these loud, elaborate songs. Instead of a high-pitched call, they use their wings to make clicking noises.
Strange Things Can Happen During the Cicada Emergence
Some cicadas this year will fall victim to a parasitic fungus that makes them into ‘zombies.’ The fungus called Massospora cicadina forces the cicadas to flick their wings in a way that attracts cicadas of both sexes, to then infect others with spores.
The wing flick is only seen in female cicadas, but males will mimic the wing flick to infect other males once infected. These spores can also infect nymphs that will emerge in the next 13-year to 17-year cycle. The spores are highly noticeable and appear as white powdery growth on the ends of the cicadas’ abdomens.
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Frequently Asked Questions About Cicadas
What Is a Cicada?
Cicadas are insects that can reach up to two inches in size and produce loud, shrill sounds and rhythmic songs. There are over 3,000 different species of cicada, and they can be found in forests, grassy areas, and even deserts. Various species of cicada have a unique song that differentiates them, as well as their appearance and behaviors.
What Is the Most Common Type of Cicada?
The most common type of cicada in North America is the dog-day cicada. Unlike periodical cicadas (which only occur in North America), dog-day cicadas are seen every year and are bigger than periodical cicadas. Dog-day cicadas are also green with black markings, have green wing veins, and have black-colored eyes. Periodical cicadas, on the other hand, have red eyes and orange wing veins.
What Do Cicadas Eat?
Note: The larvae shown is a dog-day cicada, not a periodical cicada. (Credit: Gerry Bishop/Shutterstock)
Nymphs, or immature cicadas, live in the soil and feed on the sugary sap of tree roots. This does not harm the trees.
How Do Cicadas Make Their Signature Noise?
Cicadas have an organ called a tymbal near the top of their nearly hollow bellies. Males have these located in the first abdominal segment and produce the sound when they vibrate the tymbal by contracting their muscles. The insects also have air sacs that amplify the sound. At most, male cicadas can make 300 to 400 sound waves per second with each vibration.
Can Humans Eat Cicadas?
(Credit: Thao Lan/Shutterstock)
Yes, humans can eat cicadas. There are many recipes out there for making cicada-infused treats. From cicada tacos and cicada-rhubarb pie to banana cicada bread, these insects can make for both sweet and savory treats. Some even say that cicadas taste like canned asparagus. The cicadas are mostly eaten while they are still nymphs.
Are Cicadas Dangerous and Do They Bite?
Cicadas do not bite or sting. They don’t have teeth, and their mouths are more like straws for drinking sap. They do not pose a threat to humans or pets.
Article Sources
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Elizabeth Gamillo is a staff writer for Discover and Astronomy. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern and was a daily contributor for Smithsonian. She is a graduate student in MIT’s Graduate Program in Science Writing.
