Depending on where you live, you might have noticed a new winged critter popping up… everywhere.
Don’t worry! Despite their giant, buzzing wings, unending eerie song, and those bright red eyes, cicadas aren’t here to do any harm. And this year, they’re actually a natural event you won’t want to miss.
These cicadas are known as periodical cicadas. While cicadas are common all over the world, they’re typically shy and hard to spot. Most live for a few years, spending their nymph stage hiding in the ground until the time is right for emergence. Annual cicadas emerge in waves, staggered so that a population–but not the whole generation–emerges every year. In contrast, periodical cicadas live in synchrony, all emerging at the same time. For those of us aboveground, that means every few years, billions of cicadas take to the skies in unison.
We sat down with Dr. Charles van Rees from the University of Georgia to get the full, bug-eyed picture on periodical cicadas. Van Rees helps lead the Network for Engineering With Nature’s Biodiversity Working Group, which works to explore and account for the biodiversity impacts of infrastructure decisions to advance sustainable development.
“The annual cicadas you’ll notice are typically kind of camouflaged. They’re very wary of anything. If you get near one, they’re going to fly away,” van Rees explained. “These animals have none of those defenses. They’re not particularly subtle. They usually have orange wings and dark blue bodies and red eyes. They’re not really that afraid of people, or anything else for that matter. And that’s because they just come out in such enormous numbers, that the predators that feed on them could not possibly eat them all. It ensures survival. There’s just no way that they can all be eaten.”
This survival strategy is known as predator satiation. Periodical cicadas also evade predator population cycles by emerging at seemingly random intervals of 13 or 17 years.
“So we have a whole bunch of different species in this genus Magicicada, which are the periodical cicadas. Their Latin name actually does just mean magic cicada, because oh my gosh, they’re so cool.” The genus includes seven species, each with their own emergence timeline. Each emergence event is known as a brood, and broods are often made up of two or three Magicicada species. When multiple broods line up, you get a once-in-a-lifetime occurrence that, you guessed it, is happening right now.
“This year, there are two broods, Brood XIII (13) and Brood XIX (19). Brood XIII is coming up through the north, like Michigan, Illinois, the southern parts of those states,” van Rees explained. “Then there’s another one called the Great Southern Brood–which, what a cool name–also known as Brood XIX. That consists of four species, and they’re coming up from further south in Georgia, Appalachia.” Brood XIX is the most widely distributed brood of 13-year cicadas, while Brood XIII is made up of 17-year species. Since both broods are operating in prime numbers, it’s extremely rare for them to line up: they last emerged together in 1803, and won’t see each other again until 2245.
That’s not all. You may have traveled to the path of totality to view the eclipse last month, but would you travel to see cicada emergence in totality? “Around Illinois, there’s going to be an overlap of both of these broods,” van Rees described with pure naturalist glee. “So there will be a core area where you’re getting a double whammy, just five different species of Magicicada going absolutely nuts and covering everything.”
While billions of bugs might sound a bit disturbing, there’s no need for alarm. “I think people just find them unsettling when they come out in giant numbers,” van Rees said. “They leave their funny little shells and they die everywhere, because they’re not out there to live a long life. They’ve been underground for 17 years, since 2007, listening to Linkin Park or whatever, and then they lay their eggs, and then they croak. They’ve got one job and once that’s done, they’re good to go.”
Cicadas aren’t harmful to plants, unlike the commonly-confused locust (locusts are in a completely different order, Orthoptera, with crickets and grasshoppers). Van Rees noted that while cicadas don’t typically bite, if you hold them for long enough, they may forget you’re not a plant and, well, see how you taste. “They can bite and supposedly it really hurts,” he said. “But they’re just not aggressive animals, and I don’t think they bite as a defense. They’re very harmless.”
Van Rees also warned against calling the exterminator on these gentle giants. Periodical cicadas rely on their numbers to keep their populations going. “They need to come out in ginormous numbers. If ten thousand periodical cicadas come out one year instead of ten billion, that generation is going to be gone forever. They’re all going to get eaten because there’s enough predators to consume them. Then, that’s it. That population is now extinct,” van Rees explained. “And that’s been happening–we’ve started to notice that where we’re developing these landscapes so much, the fragments of forest that they need to live are getting smaller and smaller, so the broods are getting smaller. And once they start getting down to even the millions, it’s not enough anymore for their life history to be successful.”
So get out there and enjoy this bio-phenomenon! “Take pictures and show people that it’s kind of a fun thing. It’s just like the eclipse. Go see it,” van Rees encouraged. “It’s a magical thing that’s unique to our area and unique to our lifetime.”
Read more about biodiversity research in the N-EWN here. For more information on nature topics from cicadas to forest bathing, visit the Gulo in Nature blog. You can also check out Dr. van Rees’s article on periodical cicadas here.
Featured image (top) by Levon Avdoyan via Flickr.
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