ST. LOUIS – Cicada season is well underway in St. Louis. Maybe you’ve seen them. Maybe you’ve even eaten them. One thing for certain: They’re hard to ignore.

Experts tell FOX 2 we can expect as many as 1.5 million cicadas in a brood per acre. Videos shared with FOX 2 have shown countless cicadas bundled together on trees and other surfaces in the St. Louis region.

What gives? It seems a lot of people are wondering. FOX 2 has learned of a spike in cicada-related searches from Google Trends in recent weeks.

Dr. Kasey Fowler-Finn, Ph.D., an associate professor of biology at St. Louis University, joined FOX 2 on a Zoom call earlier this week to tackle some frequently-asked questions. She’s closely studied the emergence of cicadas, locally and nationally, this year.

Presence in St. Louis

QUESTIONS: What is the prevalence of cicadas in the St. Louis area? Is there a way to quantify how many are emerging?

ANSWER: “So, it’s going to be really patchy right now. There are some places in the St. Louis region where they’re out in full force, and they can reach up to 1.5 million individuals per acre.

“Then there are other areas in St. Louis where you’re just starting to see them. For example, I was walking around Tower Grove Park, and I saw like three of them. One was flying, and a couple were dead, and they’re not singing yet there.”

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Life cycle

QUESTIONS: Generally speaking, what is the life cycle of a cicada? How long can they live above ground?

ANSWER: “Usually, once they emerge and mull into adulthood, they last about five to seven weeks. In the St. Louis area, we already had some out in the last couple of weeks. They’ll probably all be gone by the Fourth of July essentially.”

“But it’s going to be patchwork. It just depends on soil temperature. They start to emerge from the ground when the soil temperature reaches a specific level. And so some sites are just warmer than others. It’s going to be a little bit more prolonged than just the five to seven weeks you might have in a single site.”

QUESTION: What happens to cicadas as they go through their life cycle?

ANSWER: “The whole life cycle, we usually think about the life cycle of the cicadas starting when they emerge from the ground because that’s what we see. But they spent 13 years underground before that, which is kind of incredible. So once they emerge, they latch on to a tree and shed their exoskeleton, and then it takes them about an hour or two to pump up their wings and their body and start to harden into the adult form.”

“After that, it takes about five days for males to start singing. A little while after that, females will start becoming receptive. They’re singing essentially to attract beings. So they’ll do that for a while. And then once females have mated, they typically only mate once, and they will lay eggs in the branches of trees, underneath the bark.”

“The eggs will stay in the stems for about six to eight weeks, and then the eggs will hatch and the babies will emerge. They’re about the size of an ant, and they will fall off the tree into the ground, and then they’ll burrow down about two feet underground and attach onto the rootling of that tree and start eating and growing. And then they will not see the light of day for another 13 more years.”

“I think they’re so cool. You spent 13 years underground and then you come out just to mate. That’s incredible to me. If you think about it, 13 years of your life and only like five weeks are you actually doing anything above ground, and it’s all about finding mates and reproducing. To me, that seems really incredible.”

How long are they here?

QUESTION: How long should people expect to see cicadas this year?

ANSWER: “It all sort of depends. Because it’s tied to soil temperature, they’re going to emerge at different times. But I would say, definitely, for the next four to six weeks, they’re going to be around and singing. They’ll probably peak in about two or three weeks, but they’ll still be pretty loud for a long time after that.”

Their purpose

QUESTION: How do you qualify the environmental benefits that cicadas may have for the average person?

ANSWER: “I think about it more like environmental consequences. Every organism changes the environment in different ways. It could be good or bad, depending on the situation. But one thing the average person might look at underneath the tree is, ‘Do you see these little holes where they’ve emerged?’ They’re massive insects, and so they have to create these large holes to get out of the ground. And that’s actually natural aeration to the soil.”

“Mature trees are not going to be too affected by cicadas feeding on them underground, but younger trees might be. Younger trees might have a little bit of a harder time, but that soil aeration will help absorb extra groundwater and all that type of thing. It’s also just this massive influx of food into the ecosystem. So birds will have a feast. That actually can have a later consequence of the bird population growing larger and then crashing when that same food source is not available in the next year.”

“Whether it’s a benefit or not, to the local ecosystem depends on a number of things. If people are turkey hunters, turkey populations tend to have a big boom after cicadas. They also help with nutrient cycling. Once they die, they decompose and go back into the soil and that infuses the soil with a lot of nutrients. So that can help plants and other organisms grow.”

Cicadas swarm St. Louis – You have questions. We have answers.

Impact on humans

QUESTIONS: Do cicadas bite? Are there any other potential consequences they could present to humans?

ANSWER: “Their mouthparts are specialized for feeding on trees. They have these piercing mouth parts, so they’re not going to bite you. People with shellfish allergies might notice that they’re breaking out in hives. I was actually talking to my allergist the other day and she said that she’s found that people with shellfish allergies, their dogs will eat cicadas. They just think they’re delicious. Then they’ll lick their humans, and the humans will break out in hives. So that’s something to be aware of if you have a shellfish allergy that you might have some adverse reactions.”

“Otherwise, I just think it’s so cool. Like, when do you ever get millions of insects in one small area? It’s every 13 years. It’s incredible to me. But I don’t think people should be afraid of them. Yeah, you might have to crunch through some piles or sweep them away, but they’re not going to hurt you. They’re actually really clumsy flyers. When they fly, they’re like super slow and kind of bumbly. And so they’re not like going to come after people and attack them. They’re probably way more scared of you than you are of them.”

Eating cicadas

QUESTIONS: Can you eat cicadas? Are there any certain considerations you need to eat them properly?

ANSWER: “Again, people with shellfish allergies might want to take some caution before they eat them. Typically, people get them like right when they’re emerging, and that’s when their skin is really soft. So they’re sort of like softshell crabs.”

“I don’t know what they taste like, but I would imagine other crustaceans and other arthropods, like shrimp. … I would encourage people to make sure that they’re humanely killed before you put them in the pan.”

NOTE: There will be a demonstration on properly eating cicadas on May 24 at the Butterfly House.

Noises

QUESTION: “Why are cicadas noisy?”

ANSWER: “They are so loud because they chorus together at the same time. It’s not just like a single male. It’s a bunch of them all at once. When you’re somewhere with thousands of chorusing insects, it’s going to be loud no matter what.”

“You can hear them from pretty far away. They tend to be louder than the annual cicadas that we think about kind of later in the summer just because of the sheer numbers of them. It can get up to over 100 decibels if you’re right near a tree that’s loaded up with cicadas. If you’re going for a walk and talking on the phone, you’re probably not going to be able to hear your conversation. If you’re in an area with a lot of cicadas, a lot of periodicals.”

“The sounds are all about finding mates. The males have this ‘ARRAY’ that we all kind of associate with cicadas, but then they also have other sounds. The females do this wing flick, which sounds like snapping fingers. That’s how they lead the male know, ‘I hear you’ and “I’m interested.’ Then the male switches to the courtship song, and they do what’s called dueting, where they exchange signals back and forth until they mate. If males nearby are quiet, you want to hear them, you can go up and snap your finger to get them to sing.”

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Males vs. females

QUESTION: Is there a way to distinguish between male and female cicadas, other than by their sounds?

ANSWER: “The males are going to be the ones that are singing. That’s one big thing. The next one is that you’re willing to pick them up, you can flip over. The females have an ovipositor in the bottom. Their abdomen is like a line that goes down the middle. That’s a specialized structure. It’s similar to the stinger on a bee, except the cicadas fold it up. They use that to insert the eggs into the branches. If you’re willing to pick them up and look, the females have that really distinctive line down the middle that you can look for.”

St. Louis impact vs. elsewhere

QUESTION: Is St. Louis’ cicada situation similar to the rest of the United States in terms of cicada emergence?

ANSWER: “Cicadas will have fairly similar types of impacts on local ecosystems no matter where they are. Even within a given region, they can be at really high or low density. Depending on where you are in any given region, they might have a stronger or lesser impact.”

“Right now, the Brood 19, the 13-year, cicada brood that’s out in the St. Louis region, is actually the most geographically widespread. Even though they only come out every 13 years here, there’s patchwork across the United States. In the eastern United States, they come out at different off-cycles from each other.”

“All seven species of periodical cicadas are out right now [in the United States]. And that happens like every 15 or 20 years, but having them kind of adjacent like that is really a unique thing.”

What else?

QUESTION: What else should people know about cicadas? Not necessarily as a Google-trend question, but just for additional context.

“I like these stories that there’s this fungus that causes males to sing like females, so it causes males to do the wing-flick behavior. It actually gets other males to come closer to them, and then the fungus transfers from one male to the other. So it spreads that way, and this is like what we call like a zombie fungus. They hijack the insect’s nervous system and they could behave in a way that helps spread that fungus.”

“Also, we have the 13-year cicadas. We call it, Brood 19. But there’s actually four different species in that brood So all four species have synchronized together, and then the 17-year brood that’s out. It’s three different species, and they’re all synchronized to come out at the same time. You might go from one spot to the other and hear slightly different songs. That’s because there might be different species, but they all emerge at the same time.”

“I’ve studied sound for 20 years, so to me, I can always hear the differences, but they’re different pitches. If you have a trained ear, you’ll be able to pick out different species.”

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