Invasive Ants Are Taking Over New York City

Written by Rudi Molinek on August 23, 2024. Posted in Current News

Since appearing on Manhattan in 2011, the species has become one of the island’s most dominant ants, and scientists formally identified it this year

It all started on a few road medians on Broadway, at 63rd and 76th streets, in the middle of New York City.

In 2011, biologist Rob Dunn from North Carolina State was in town to teach classes at Columbia University.

During a break, he stepped outside and collected some ants. Back in the lab, he looked at them closely and concluded they didn’t match any of the 13,000 ant species known at the time.

At first, it seemed like he might have picked up a totally new species that evolved in the Big Apple. “It’s new to North America, and we believe it’s new to the entire world,” Dunn told the New York Post’s Annie Karni in 2012.

With no immediate match to a previously named species, the insect acquired the nickname “ManhattAnt.”

Now, more than a decade later, scientists have formally identified the ManhattAnt for the first time. While it’s not a completely new species, it is still a surprising arrival from Europe called Lasius emarginatus, according to a study recently published in the journal Biological Invasions.

Researchers had suspected the ants were L. emarginatus, but this paper confirms their identity with 93 to 99 percent certainty.

My master's work and first publication on Lasius emarginatus in NYC is officially out in @BioInvasions today! I'm proud of all the work and collaboration that made this paper possible. ClintPenick @twpierson @RRobDunn BernardSeifert https://t.co/cN7RjvKK6O

— Samantha Kennett (@smkennett4) May 28, 2024

Since the ManhattAnt’s original Broadway debut, it has seized a place among the city’s most dominant ant species. And there’s no sign it’s slowing down. The ManhattAnt has expanded out of Manhattan and has been spreading at a rate of more than one mile per year into New Jersey and Long Island, per the study.

“We predict that they could expand as far north as Maine and as far south as Atlanta, Georgia,” Clint Penick, a biologist at Auburn University and co-author of the study, tells NPR’s Nell Greenfieldboyce. “This is an ant that could become quite common throughout the East Coast.”

Despite its success in Manhattan, L. emarginatus isn’t dominant in any areas in its native Europe, and it isn’t especially known as a species adapted to urban spaces. This makes its New York City takeover even more unexpected.

To collect ants for study, researchers suck them up into little tubes like drinking soda from a straw. Back in the lab, they look closely at the physical characteristics of the ants and analyze samples of their DNA to compare with known species.

These tests matched the ManhattAnt with L. emarginatus.

Besides going out and collecting ants themselves, scientists can learn about the spread of different species through citizen science efforts like Project ManhattAnt on iNaturalist. This program lets non-scientists report local sightings of the insect.

Sometimes those sightings are more dramatic than some New Yorkers might prefer. Unlike many other species of ants in the city, the ManhattAnt likes to climb, walks quickly and is comfortable on relatively smooth surfaces like concrete.

So, Katie Guhl was surprised when she came home from a long weekend in May 2022 to find the sixth-floor kitchen she had left spotless covered in a swarm of ants.

“There were no crumbs to be had,” Guhl told the New York Times’ Dodai Stewart in 2022. She had never seen ants in her apartment before, but the newly arrived ManhattAnt was willing to make the climb in search of treats.

Beyond being an annoyance to high-rise dwellers, the invasive ManhattAnt might pose a serious ecological threat. Some researchers worry about the impact the species could have on the city’s tree population, which removes 51,000 tons of carbon and 1,100 tons of air pollution each year while saving $17.1 million in residential energy costs.

The ants feed on honeydew, a sugary substance secreted by aphids and other pests—and as a result, they form mutually beneficial relationships with these tree-damaging insects, per the paper.

It’s “entirely possible” that ManhattAnts could hurt trees in the city, the study’s lead author Samantha Kennett, an urban ecologist at Clemson University, tells NPR. “I wish we could just see what they were doing all the time.”

For now, it seems like the ManhattAnt is living its big city dream—but it might soon be looking to upsize to a nice spot in the suburbs as the species continues to spread.

See more here smithsonianmag.com

Header image from the 1954 movie Them!, courtesy film freedonia

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