VOL. 48 | NO. 19 | Friday, May 10, 2024
Science of cicadas
By Lucas Hendrickson
Very soon, through big swathes of the Volunteer State, the cicadas are gonna remind you of Roy Kent.
The veteran, albeit fictional, British footballer from “Ted Lasso” had a chant directed at him throughout his career: “he’s here, he’s there, he’s every-(effin’)-where…”
For the next six weeks or so, the periodic cicadas of Brood XIX will be much the same way.
Granted, overlapping broods of annual cicadas, with life spans ranging from two to five years, emerge every year with larger bodies but much smaller numbers.
But specific broods, with either 13- or 17-year life spans, lay in wait to bedevil and delight, with molted nymph forms, bright green coloring and vibrant red eyes either capturing the public’s attention or adding fuel to nightmare fires.
Let’s take this moment to reassure the newcomers to the southeast in general and Tennessee in particular who haven’t experienced a cicada tsunami before: They won’t hurt you. Or your pets. Maybe your psyche, but suck it up, buttercup, and enjoy the ride.
Bugs as part of business
Midhula Gireesh, assistant professor and extension specialist in the Nashville office of the University of Tennessee Extension System, probably wouldn’t put it quite so vividly. But she understands that perhaps not everyone is as excited as she is about this year’s cicada coming out party.
“I’m super excited because I want to see how this is coming to me,” Gireesh says. “I call it being a bug enthusiast. We don’t know, there might be future entomologists gaining interest by seeing such phenomenal events.
“People like that, get out and enjoy and see how these things are coming up from underground and then spending their time,” she continues. “But, don’t worry, it’s not going to harm you or your pets. It’s not going to sting or bite. It just comes and probably it’s a little bit annoying, but it will be over.”
While Gireesh will be using part of her time as an enthusiast observing, she’ll also be using her time as a professional reporting on the brood’s activities and helping advise her clients on how to mitigate damage to young trees at nurseries around the state.
Part of the UT Extension Systems long history of working with agribusiness operations throughout the state is using both scientific and economic specialists to help growers assess market trends and risk management strategies. Gireesh, originally from India, got her Ph.D. at the University of Georgia studying the impact of billbugs (a type of weevil) on turf grass systems.
“I was not an entomologist back in India. I was mostly doing molecular studies and genomic science,” she says. “So I have that expertise of both molecular biology work and turning into an applied entomologist when I came to America.
“My appointment here is working with insect pests of turf grass, ornamentals both nursery and landscape pests. So I’m actually 100% (working with) Extension, which means that I’m giving training to the extension agents about major pest problems.”
Nymphs spend almost all their lives feeding on plant roots. Their internal clocks tell them when to emerge.
-- Shutterstock.ComNot that she seems to classify the emergence of Brood XIX as a major pest problem, but more as an opportunity to expand the knowledge base, especially since the 17-year Brood XIV (entomologist Charles L. Marlatt first proposed identifying the broods by Roman numerals in 1893) will emerge more broadly throughout Tennessee in 2025.
“Extension agents are the face of the field. So we make them aware that this is going to be coming, and get them prepared with all the resources,” Gireesh says. “They are kind of like the first line of responders. I sent out an email for all the Extension agents because I have a statewide responsibility. So if we see any Facebook pages that are reporting about cicadas, any recent publications regarding them, I send it to all the extension agents statewide so they can hand it out to their growers who are going to be dealing with this.”
Boots (shells) on the ground
Gireesh says she and her team use many publicly available tools such as the app Cicada Safari and accompanying website (cicadasafari.org), spearheaded by Cincinnati’s Mount Saint Joseph’s University and updated by a number of higher education organizations, including Nashville’s Belmont University.
“We’ve got this year, and then from that we can help predict how big this is going to be next year. This year, it’s probably going to be concentrated in Middle Tennessee and some southeastern Tennessee counties, but next year, from what I heard from my predecessor who had this job previously, it’s going to be bigger,” Gireesh says. “So what we can do from our end is revise those predictions that were revised in 2021 and provide the latest research that is happening.
“I’ll probably be traveling around quite a bit since they’re pretty quick to emerge. I can also see from the (Cicada Safari) app where things are happening,” she continues. “With the nurseries, unfortunately, it’s very difficult in terms of managing them because we are talking about huge hectares of plants.”
But this summer is all about Brood XIX, which last emerged in 1998 and 2011 and are still talked about in terms of the sheer volume of noise generated by the male cicadas issuing their mating songs.
“I’ve heard people in the office I’m in say they couldn’t even talk because they couldn’t hear anything over the singing,” Gireesh says. “I’ve seen an article from elsewhere saying someone called the sheriff because it was so loud and they didn’t know what was happening. So these things kind of make sense.”
What will this summer hold?
Cayty Stubblefield grew up in Shelbyville and remembers well the 2011 invasion, since “bugs are my jam.”
Stubblefield spends her time these days as part of the field crew for Habitat Landscapes, a Nashville-area company specializing in garden design, invasive plant removal and small hardscaping projects within horticultural installations for which they’re hired.
But in 2011, she was still a high school student and was thrilled by the phenomenon she got to watch up close and, as was the case with some friends, up very close.
“I remember them just being everywhere,” Stubblefield says. “I remember walking around town in Shelbyville, and they’re all over the sidewalks and all over the trees. They’re buzzing through the air, they’re getting stuck in my friends’ hair and they’re kind of freaking out.
“Cicadas, they’re kind of bumble butts, you know?” she laughs. “They’re not very good at directing themselves while they fly, so they wind up flying into people or getting stuck in your car. I remember that happening a lot that summer.”
After what she calls a long stint in the restaurant industry, Stubblefield went back to school for a biology degree from Middle Tennessee State. She then started getting her hands dirty with landscaping projects and apprenticeships before locking in with Habitat’s crew full-time.
Like Gireesh, she’s also spent a good deal of time digging into the research of what periodic cicadas do and don’t do and sharing those findings with the company’s homeowner clients.
“I’m definitely clicking on every article I see that has to do with cicadas,” Stubblefield says. “There’s so much information out there that you can gather about them, from their life cycle to how they interact with other elements of our ecosystem, what they eat, what eats them, learning about what so many cicada carcasses will be contributing at the end of all this.
“They go up to trees with young limbs on them because they’re a little more tender. They can sort of drill their way down into the cambium layer (the layer that grows new bark and wood) of the branch, and they suck out the saps and juices from the plant, and that’s how they get their nutrients,” she continues. “When the females lay their eggs, they kind of do the same thing, just from the other end. Instead of sucking out juices, they’re depositing their eggs in the young branches.
“With our annual cicadas, the damage that they can cause to the limbs is pretty minimal. You don’t really notice damage in your garden or landscaping from the annual cicadas, but the volume will be so high this year,” Stubblefield says.
“Most plants that we’re installing, like flowering herbaceous plants, aren’t really going to be much of a concern because they don’t really feed on those. They’re mostly looking for really small, young, tender branches.”
Stubblefield’s boss, Habitat Landscapes owner Ivan Chester, says the basic advice they’re giving to clients right now is simple? Don’t freak out.
“For the cicadas, it’s such a brief thing that I feel like whatever damage occurs is going to be mitigated within a year, and then it’ll be another 13 or 17 years before it’s a problem again,” says Chester, who launched the business in 2018. “Trees are extremely vibrant and will grow in any situation, so having a natural control on them is kind of important.
“Cicadas are one of those, but as a homeowner it’s kind of a bummer because you’re trying to grow your trees and shrubs that are desired for your lawn,” he continues, “but if you’re trying to artificially grow a tree where it doesn’t occur in nature, then you’re going to have to also artificially support it.”
Chester says this year’s emergence and the prospect of next year’s larger one are giving some potential clients pause about new planting.
“I’ve had a few clients that are delaying plant installations. They’re going ahead and signing the contract and setting an installation date for later in the summer. We’re just doing some prep work and waiting until the cicada wave is over.
“And then I’ve got some clients that want to go ahead and get plants in the ground,” Chester continues, “so we’re using tulle fabric, stuff that dresses are made out of, and securing that around the canopy of the small trees where it’s feasible to do so, then securing that at the trunk with a zip tie or a piece of arbor tie.”
Always something to learn
Much like any other observable natural phenomenon, there’s still so much to learn about the existing habits and potential futures for periodic cicadas beyond just tracking their life cycles.
Gireesh says she’s paying close attention to how climate change in the state has already affected this brood.
“We predicted the emergence to be closer to Mother’s Day, but we started seeing them toward the end of April because the temperatures started warming up really early. These things definitely have an impact on their population because their habitat is changing every day.
“I am very interested to know at what temperature they start singing. And since I’m seeing them for the first time, I need to know everything basic, like what time they are emerging,” she continues. “From what I heard from other experts, they come in the night, so I want to know after what time they are (molting and) becoming the adults, and how they are probably doing the damage. These are the little things I’m excited about, and also to know how it’s going to impact the nurseries and landscape industries.”
For Stubblefield, the note that has caught her attention is observance of a fungal infection known as Massospora cicadina.
“It’s basically a sexually transmitted disease among these cicadas,” she laughs. “They’re spreading this fungus among each other and it’s sort of like the fungus kind of takes over the cicada’s body, sort of eats it in a way while the cicada still kind of goes about its business like it tries to mate.”
(If this sounds like the plot to “Attack of the Zombie Cicadas,” you’re not entirely wrong.)
“It still will eat a little bit and as time goes on, those things kind of slow down, and then apparently the genitals of the cicadas are falling off sort of like shortly before they die from this and if you see a cicada that has, like, a white plug coming out of it that could, that’s an indicator that it has this fungal disease that is kind of spreading through them.”
Still, cicadas can best be viewed as another harbinger of summer … just one that has a little more buzz and crunch to it.
“The southeastern United States is very biodiverse, and this is kind of a neat phenomenon, so enjoy it. Have fun with it,” Chester says. “Take lots of pictures and protect your plants that are highly susceptible, which are going to be your young trees and woody shrubs, especially newer ones that have just been planted.”
Stubblefield concurs with her boss’ observation. “I think that they are, one, very interesting looking. They’re big, so you can get a really good look at them. They’ve been around and evolving for 4 million years, so they’re an ancient bug and kind of archaic looking. You can tell that they’re from the land before time, basically.
“They’re slow-moving, so you can get a good look at them without them flying away,” she continues. “You can get great pictures of them when they first come out of their nymph forms and they’re emerging into their adult form. When they molt they’re beautiful with these neon green colors, so that’s eye-catching and cool to see.
“To me, cicadas have always been this huge symbol of summer. All this great summer fun stuff and cicadas are kind of always in the background of that, at least here in the southeast. So I think that there’s a little bit of intrigue and romanticism to them.”