Short Wave - This Unremarkable Ant From Europe Quietly Conquered NYC

Episode Date: August 26, 2024

New York: The city that never sleeps, the concrete jungle where dreams are made of and more recently ... home to a mysterious ant spreading across the city — before continuing across metropolitan and even state lines. NPR science correspondent Nell Greenfieldboyce joins host Regina G. Barber to trace the MahattAnts' takeover, explain why they're an interesting invasive species case study. Plus, how everyday people can get involved in research efforts to learn more about these critters.Read more of Nell's ManhattAnt story here. And if you like this story, check out our story on ant amputation!Interested in hearing more animal news? Email us at [e-mail]. See pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences.NPR Privacy Policy

You're listening to Shortwave from NPR. Hi, Shorewavers. Regina Barber here. The city in the United States that has the most people is New York. You know, the big apple. The place is full of skyscrapers. And if you went up one and look down, you'd see all these people like down below, tiny, tiny little people scurrying around from place to place looking like ants.

Real ants? Vastly outnumber human New Yorkers. Scientists have actually done some calculations proving this by looking at the number of ants per square foot. But most of the time, the ants go unnoticed. That's why, as I've recently learned, beneath the feet of millions of people, one particular ant has managed to take over Manhattan.

And I know this because of our intrepid aunt correspondent NPR's Nell Greenfield Boys. Hey, Nell. Hey, Gina. I do feel like I talk to you guys about ants fairly often. I love it. Yeah, this ant has been sort of covertly conquering Manhattan since it first showed up.

there in 2011. And, you know, back then, researchers knew it had to be a brand new arrival because they'd been doing surveys of the city's aunts like a few years before and, like, they hadn't seen it. Wow. Okay. So 2011, that's like not that long ago. Like, where did it come from? No one knows how it got to New York. And at first, scientists weren't even sure what species it was. For all they knew, it might have been a species unknown to science. So, you know, you had this mysterious aunt living in like the traffic medians on Broadway. And as you can imagine, in like, a media capital like New York, this made headlines, like The New York Post, dubbed it the Manhattan ant. They love their puns.

I love it. But, you know, after its moment of glory, the news cycle moves on and this ant sort of fell off everyone's radar screens, like, for years. I mean, human radar screens. I wonder if, like, the other ants were aware of it. Oh, no doubt. No doubt. I mean, people, like, people who are not insect specialists generally cannot tell one dark brown ant from another. I mean, I assume the aunts have no problem, but I was talking with Izzy Kaplan. She's a student at Fordham

University. That's a couple of blocks from Central Park. And here's what she told me. At first, I didn't know what it looked like, so I didn't know what to look out for. But ever since I saw one picture, I was like, oh my God, I've seen them everywhere. They were not hard to find. When I met her at her university's plaza, she took me over to this concrete wall with just like some vines and stuff. And the Manhattan ants were crawling around. And she had this contraption with plastic tubes that researchers used to basically suck ants into this little clear vial. That's so cool.

I got one in here. There's a bunch of debris in here, but you can see it climbing up the side. And it has the red thorax. So that's how you can tell that it's the Manhattan. It's got this reddish midsection that is so distinctive. No other ant around has that. and the ant is fairly large. So all of this means that interested people have been able to spot it fairly easily.

And, you know, they've been uploading sightings into the I Naturalist website. And those sightings show that it is definitely spreading. Like, this is an unusual situation where you have, you know, the exact introduction time of a species known. And then, you know, it's easy to track it because it's distinctive and it's spreading in a place where There's millions of people. And what the sighting show is that this ant is not satisfied with just taking over Manhattan. It is moving into the outer boroughs and beyond. I mean, look out East Coast.

This ant is coming your way. That's just what we want to talk about. So today on the show, what this ant is doing, why it's been so successful, and what happens when a new species arrives in a place it's never been before? You're listening to Shorewave, the science podcast from NPR. Okay. Now, we were talking about how scientists, like, they had really no idea what this ant was when it first turned up in New York a little over a decade ago. Like, when did they figure it out?

Okay, so the ant's official, like, solid identification was just published this year. Oh, wow. I mean, after it was first spotted in New York, honestly, scientists kind of ignored it for a while. I mean, it wasn't in very many places. And no one had any idea it was going to become this huge deal. I mean, one researcher told me, you know, they were. were busy working on other things, but this aunt was busy working on New York. I was talking to Clint Pennick of Auburn University. And he told me that the ant just started showing up more and

more frequently when he was collecting ants in the city. And he eventually got sick of having to catalog it as just this kind of unknown species. So he and some colleagues went on a quest to nail down what it was. It turns out to be an ant normally found in Europe. It's quite common. So it's found in southern England and the Netherlands and down in Spain and then down to the Balkans. That's why he thinks in the United States it could eventually spread from Maine to Georgia. Wow. And when he consulted like the world's expert on this species and ant specialist in Germany, that guy was shocked to hear that this aunt was living it up in the city that never sleeps.

He was like, they're not even really dominant in any European area. They're not known as urban pest. And so it was quite surprising that this species of all of the different species that could make it over from Europe was the one that was taking over Manhattan. It's so fascinating. Like where does it live in Europe? Like forests, small towns or something? Basically forests, yeah. And I mean, occasionally in more urban areas, like parks. I mean, maybe it came over to the U.S. in the dirt around some plant roots or, you know, who knows. But in New York, are they sticking to parks? No, no, that's just the thing. They are. Everywhere.

Wow. The streets, the sidewalks, the trees. One researcher told me there's ants on her stoop. She passes several colonies as she walks to Trader Joe's. I mean, it is all over Manhattan. And it has moved north up into the Bronx, south into Long Island. Clint Pennock told me one day he went to a friend's place over in New Jersey. And when he got off the subway...

Manhattan ants were there. So, like, at this point, they had crossed the Hudson. These ants are probably spreading during their mating. season. That's when they sprout wings and can fly short distances. And, you know, so far, they've been moving out about like a mile a year. Although at some point, they could hitch a ride and spread farther. And, you know, they could already be in more far-flung places and people just haven't noticed. Yeah, because what we said, right, like people don't often notice, like, ants. Yeah, unless they bite or sting, which these don't. Actually, though, to be fair,

these ants do sometimes get noticed. Like, when they climb way up into the same thing, and Manhattan high rises, that is actually unusual for an ant to do. And so, like, the New York Times did a story a couple years ago about why people were suddenly seeing ants like up on the 20th floor and stuff like that. Besides being climbers, these ants are also unusual in that they are speedwalkers. They move really fast. I mean, I'm still getting over them, like, climbing 20 floors. But, okay, so they're moving really fast, like other New Yorkers. Like, I've only seen this in movies. Yeah, you see people famously kind of rushing through the streets. Clint Pennick told me, ants normally avoid the sidewalk, except, you know, there's this urban

ant called the so-called pavement ant. It's this other introduced species from Europe that's now in a lot of U.S. cities, including New York. But it's clear in New York, the pavement ant now has serious competition. I started to see these huge foraging trails with hundreds, if not thousands of these Manhattan workers just running along the sidewalk. And so this is, you know, the first time we've really seen an ant take over the sidewalk in New York City since the arrival of the pavement ant, which was, you know, at least 150 years ago. Wow.

The pavement ant has long been the most common aunt in New York, but now the Manhattan ant is vying for that title. Okay, so these Manhattan ants are like everywhere. Should this worry us? I mean, is this ant doing anything that's, like, bad for people or other living things? That is what is so interesting to me. no one knows if it's going to be trouble here. I mean, ecologists talk about something called the 10% rule. And that basically says, most non-native species that are brought to a new place,

like in a ship or something, they don't survive there. Only about 10% get established and settle in. Okay. And of that minority that manages to persist in a new place, most species don't disrupt things. Only about 10% of new settlers will become invasive people. pests. So, you know, is this ant going to be one of that small minority that gets to be considered damaging and invasive? I mean, we don't know. It's not clear. Wow. Okay. Well, what do we know

about how those ants live? Like, how are they making their living? So I talked to Samantha Kenneth Kennett. She's currently a PhD student at Clemson University. She's done a lot of work in New York on this aunt. She says, unlike the pavement ant, this one doesn't really focus on human food. Although, So, you know, in a pinch, these ants will consume some human food to some degree. Interesting. But their main sustenance is honeydew. So that's a kind of sugary poop that's excreted by aphids and other pests, like scale insects. Wow, you got me at poop.

I've literally never heard like aphid excrement be called honeydew. That's, I love it. It's a nice name for what it is. And the ants are going up into like street trees to get this stuff. That's part of how they're so successful as they've been able to, they're foraging in street trees for honeydew. But listen, scientists know that ants that like honeydew can sometimes turn into kind of like honeydew farmers, right?

Okay. Like they want to get this stuff. And so they start to kind of like take care of the insects that make it, right? They kind of herd aphids. They protect aphids from other predators. And that means you end up with more. more aphids and other similar plant pests, chewing on the plants of New York. Hmm, okay. So that doesn't sound great for these city trees, right?

I asked Samantha Kennett about that, and she says it's entirely possible that, you know, this ant could be changing something for city trees, but we don't know. I think it would be really interesting to see how, in the long term, the Manhattan ant could have effect on trees in New York or anywhere that they are invading. It's also not clear how this ant is going to interact with native ants. Ants can battle with each other. And scientists know that invaders can sometimes wipe out native ants. That's a big deal because native ants can play important roles that affect other species.

They do stuff like disperse plant seeds and forests. I mean, ants are small, but they are numerous. And that means their activities can have major consequences. Sometimes weird, unexpected consequences. I mean, earlier this year, for example, scientists published one study showing that when an invasive ant came to Kenya, it wiped out a native ant. And this led to a series of ecological changes that ultimately resulted in lions eating fewer zebras. That's really fascinating. And it seems really strange that this ant that's like spreading all over New York and further out, like no one knows what effect it will have.

I know, right? I was talking to Ellen Van Wilgenberg. She's a researcher at Fordham University who's gotten interested in this aunt. And she also studies the spotted lanternfly, you know, that one. Okay. You know, that plant pest, you know, is from Asia. And when it turned up on the East Coast, there were all kinds of news articles and TV. And everybody was urged to destroy it.

You know, there was like a huge amount of media attention. Oh. Then something like the Manhattan is there. It's probably more abundant. even than the lantern fly and no one knows. She says if you look at an influential list of the top 100 most destructive invasive species in the world, there's like five different species of ants on there. So it's like researchers right now are in this weird kind of limbo.

All they can do is watch the Manhattan go and try to understand what's happening. That's one reason why on this website I mentioned earlier, I-Naturalist, they set up a project Manhattan page where people can upload sightings and observations. Although, you know, the ants are so speedy. It can be hard to take a picture. But people do it. I think short waivers are up to this challenge. I mean, I am.

I mean, I know definitely the next time I go to New York, I'm going to be looking for it. It's like real life like Pokemon Go. Nell, thank you so much for bringing this story to us. As you know, I am always one for Aunt News. and I will bring you everything I find. Looking forward to it. This episode was produced by Rachel Carlson. It was edited by our showrunner Rebecca Ramirez

and Nell Check the Facts. Code Takasuki Chernovin was the audio engineer. Beth Donovan is our senior director and Colin Campbell is our senior vice president of podcasting strategy. I'm Regina Barber. Thank you for listening to Shortwave from NPR.