Why Do 17-Year Cicadas Come Out More Frequently Than Every 17 Years?

Quck answer

Why do 17-year cicadas come out more often than every 17 years?

Periodical cicadas, also known as 17-year cicadas, emerge in massive numbers every 17 years, but sometimes they appear four years earlier or later. This phenomenon is known as acceleration or deceleration. The reason behind this irregularity is still a mystery, but scientists believe that it could be due to a combination of factors, including climate change, predators, and genetics. Acceleration may occur when the soil temperature reaches a certain threshold, while deceleration may occur due to predator pressure. Overall, the exact cause of this phenomenon remains elusive.

Wild Animals

Feeding, Mating, and Other Behaviors of 17-Year Cicadas

Periodical cicadas, whether they belong to the 17-year or 13-year species, will only live aboveground for a mere three to four weeks. This is just enough time for them to mate and for females to lay their eggs. Although it may seem sad, this cycle of mating and dying is quite common in the world of insects.

Despite their short lifespan, cicadas are talented at attracting attention. Male cicadas emit a loud buzzing sound that fluctuates between two distinct notes in an attempt to attract female cicadas.

Although each species of periodical cicada has a unique song, the response of female cicadas remains constant. One-third of a second after the male stops singing, the female will respond with a click of her wings only if she is interested in further advances. The male will then repeat his call, hoping to hear the sound of another wing click. If he does, he will make two specific sounds in quick succession, wait for a third wing click, and then vibrate his forelegs as he mates with the female [source: Bug Music].

Within 10 days, the female cicada will lay around 400 eggs in small twigs and branches of nearby trees and shrubs. They choose from 80 different species to use as a nursery. Female cicadas have needle-like devices at the end of their abdomens that they use to create an egg cradle in the wood. They may repeat the egg-laying process many times [source: Ohio State University].

After about six weeks, white nymphs the size of ants will emerge from the eggs, fall to the ground, and burrow into the soil. They will spend the next 17 or 13 years feeding on plant root fluids, just like their parents.

Although cicadas’ root-feeding is not harmful, the damage caused by female cicadas burrowing into trees and shrubs to lay their eggs can be significant. Twigs may snap off, creating production problems for fruit and nut orchards. Some caretakers cover small trees with mesh cloth to prevent access to the bark, while others apply insecticides before egg-laying occurs or wait for the cicadas’ limited lifespan to end [source: Penn State University]. Cicadas are not harmful to humans or plants, so there is no need to panic if one lands on you.

Crispy, Crunchy Cicadas

Did you know that cicadas make delicious, high-protein, low-calorie snacks? Thanks to their plant-based diets, they taste like asparagus. The best ones to eat are those that are still in the nymph stage and have not yet developed their hard outer shells. Deep-fry them and serve with a spicy sauce [source: National Geographic].

Author’s Note: Why Do 17-Year Cicadas Come Out More Frequently Than Every 17 Years?

When it comes to periodical cicadas, biblical plagues, evil spirits according to Native Americans, and plagues according to early colonists come to mind. In 2013, millions of these large, clumsy flying insects emerged, marking the 17th year of their life cycle. They have made their presence felt among humans, including me. The trilling sound of the male cicada, whether it is a periodical cicada or the more common annual cicada, is the sound of summer in my part of the country.

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Sources

• Bug Music. “Magic Cicadas.” (May 16, 2013) http://www.bugmusicbook.com/#!magic-cicadas/cki0
• Cicada Mania. “”Are There Periodical Cicadas Coming to Your Town?” (May 16, 2013) http://www.cicadamania.com/where.html
• Cicada Mania. “2012 Brood I Wrap-Up.” Sept. 24, 2012. (May 23, 2013) http://www.cicadamania.com/cicadas/category/broods/brood-i/
• Eby, Margaret. “Paul McCartney Attacked by Grasshoppers During Concert in Brazil.” New York Daily News. May 8, 2013. http://www.nydailynews.com/entertainment/music-arts/paul-mccartney-attacked-grasshoppers-brazil-concert-article-1.1338663
• Hayes, Brian. “Bugs that Count” American Scientist (May 23, 2013). http://www.americanscientist.org/issues/issue.aspx?id=3437&y=0&no=&content=true&page=2&css=print
• Magicicada. “Why Do Periodical Cicadas Appear in Unexpected Years?” (May 23, 2013) http://www.magicicada.org/magicicada_straggler.php
• National Geographic. “Cicada Facts: Understanding the Invasion.” May 21, 2007. (May 16, 2013) http://news.nationalgeographic.com/news/2007/05/070521-cicada-facts.html
• Ohio State University. “Periodical Cicadas: Life Cycles and Behavior.” (May 17, 2013) http://www.bugs.osu.edu/~bugdoc/PerioCicada/PeriCicadaBehav.htm
• Penn State University. “Periodical Cicada.” (May 16, 2013) http://ento.psu.edu/extension/factsheets/periodical-cicada
• Staten Island Museum. “They’re Baaack! Return of the 17-year Cicadas.” (May 16, 2013) http://www.statenislandmuseum.org/exhibitions/current-exhibitions/
• University of Michigan Museum of Zoology. “Periodical Cicada Page.” (May 16, 2013) http://insects.ummz.lsa.umich.edu/fauna/Michigan_Cicadas/Periodical/Index.html
• Vanderpool, Scott. “Paul McCartney Plagued by Locusts.” KZOK. May 8, 2013. http://kzok.cbslocal.com/2013/05/08/paul-mccartney-plagued-by-locusts/

FAQ

1. What are 17-year cicadas?

17-year cicadas are a type of periodical cicada that emerge from the ground every 17 years. They are different from annual cicadas, which emerge every summer. 17-year cicadas spend most of their lives underground as nymphs, feeding on the sap from tree roots. When they finally emerge from the ground, they shed their skins and mate before dying off.

2. Do 17-year cicadas come out every 17 years exactly?

No, 17-year cicadas do not emerge from the ground exactly every 17 years. There are several different broods of 17-year cicadas, each of which emerges on a slightly different schedule. For example, Brood X emerged in 2021, but the next emergence of another brood is expected in 2024. The reason for this staggered emergence is not well understood.

3. Why do 17-year cicadas come out so infrequently?

It is not entirely clear why 17-year cicadas emerge from the ground so infrequently. One theory is that this long emergence cycle helps the cicadas avoid predators, as it is more difficult for predators to predict when they will emerge. Another theory is that the long emergence cycle helps the cicadas synchronize their emergence with other cicadas in their brood, which increases the likelihood of successful mating.

4. Why do 17-year cicadas come out more often than every 17 years?

There is no evidence to suggest that 17-year cicadas come out more often than every 17 years. While different broods of cicadas emerge on slightly different schedules, the emergence cycle for each brood is consistent. The idea that cicadas are emerging more frequently than they used to is a myth.

5. Are 17-year cicadas harmful to humans?

No, 17-year cicadas are not harmful to humans. They do not bite or sting, and they are not known to carry any diseases. However, their loud buzzing can be irritating to some people, and they can cause damage to young trees if they lay their eggs in the branches. Overall, though, 17-year cicadas are harmless and fascinating creatures that play an important role in their ecosystem.