Bug Wars: The Return of the Cicadas

June 3, 2021, 10:27 p.m. | By Katalina Li | 1 year, 2 months ago

Brood X, composed of billions of periodical cicadas, has emerged in full force and will stay for about a month.

In most years, cicadas are just another insect that we see during the spring and summer. This year, however, the cicadas are a bit different -- they are periodical cicadas that belong to Brood X. 

The cicadas we see in most years are annual cicadas that have a relatively shorter life cycle of one to two years. Periodical cicadas, which show up only once every other decade, are significantly different from the typical annual cicada; the most identifiable difference, according to wkrn.com, is that adult periodical cicadas have dark blue bodies and red eyes, while annual cicadas have black bodies and are larger in size. 

Furthermore, the life cycle of periodical cycles lasts much longer than that of annual cicadas. The life cycle of a periodical cicada is about 17 years long, compared to the yearly-based cycle of annual cicadas. However, a periodical cicada spends almost all of its life underground, continuously growing and molting. 

Once the soil at the surface of the ground reaches a temperature of 64 degrees Fahrenheit, the cicada (which is called a “nymph” at this stage) finally emerges. The nymph then molts one more time and sheds its skin onto a vertical surface -- this is why you might see a bunch of brown, hollowed out cicada-shaped shells clinging to your neighborhood trees and electricity poles. 

Once the nymph molts, it is now considered a full-fledged adult cicada. For the next few weeks, adult cicadas will mate, and each female cicada will then lay up to 600 eggs.

According to the Encyclopedia Britannica, when male cicadas want to find female cicadas to mate with, they produce a loud clicking noise using their tymbal organs (an organ that is unique to cicadas). However, female cicadas usually only mate with one male in their lives. This means male cicadas will often try to compete with each other by producing the loudest noise. This is why, on a nice summer’s day, you might hear intense “chirping” and clicking noises coming from the treetops.

After two to four weeks of mating and laying eggs, the adult cicadas die. About a month later, the eggs will hatch and the nymphs will burrow themselves deep into the ground, where they will grow for another 17 years until the cycle starts again in 2038.

“Generations” of periodical cicadas are referred to as broods. The current brood is Brood X, and the last brood that we saw was Brood IX in 2004. Brood X has billions of cicadas, and the reason there are so many of them is simple: strength in numbers. Even if predators eat a significant number of the cicada population, there’ll still be enough of them to continue mating and keep their species alive.

Cicadas are prey for all sorts of neighborhood animals, including birds, squirrels, and even dogs. Sophomore Christy Li notices that on their daily walks, her dog Lucky keeps trying to eat the hundreds of cicadas that cover the lawns and sidewalks. “He sticks his nose into the grass until something moves, and then chomps. I literally have to tell him off so many times when I walk him,” Li says. 

Brood X’s exceptionally large size is not the only thing making them unique -- according to the Washington Post, there is also a new type of fungus that is circulating through the brood. On infected cicadas, the Massospora cicadina fungus causes the bottom halves of their bodies to fall off gradually. In addition, the fungus causes the cicadas to try to mate as much as possible, even though they lack the organs necessary to reproduce without the bottom halves of their bodies. 

Infected cicadas may not have shorter lifespans, but their lives become “controlled” by the fungus. As they continue “mating” furiously, the fungus spreads quicker and quicker, and the fungi spores spread onto soil too. This means that when Brood XI emerges in 2038, even more of the nymphs will be infected by these spores. 

As of right now, the fungus doesn’t seem to have made a lasting indent on the population size of Brood X, just because of the sheer number of cicadas. However, scientists still aren’t sure if Brood XI will be different, so we’ll have to wait until 2038 to see. Until then, let’s do our best to enjoy the cicadas… or just plug our ears until they stop chirping during the night.

Last updated: June 3, 2021, 10:30 p.m.

Tags: science cicadas

Katalina Li. Hi there! I'm Katie (she/her) and I'm a senior. When I'm not writing articles, I'm usually binge-watching Gordon Ramsay shows, drawing Studio Ghibli characters, or making piano covers for my YouTube channel :) More »

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