Kennett looking for the newcomer ant species in Times Square. Photo: Rebecca Senft/Samantha Kennett/dpa
When Samantha Kennett went looking for the Lasius emarginatus – the two-coloured path ant – in New York in spring, it didn't take long to find them.
"We found them everywhere," says Kennett, who is doing a Master's in Urban Ant Ecology at Kennesaw State University in Georgia.
"We found a colony in Times Square. We found them in parks, up and down Broadway and the adjacent streets. And on almost every sidewalk tree you passed there were colonies of these ants."
In Europe, Lasius emarginatus is one of the most widespread ant species. In the United States, however, the ants, which are a few millimetres long and brown or reddish-brown in colour, were not considered native – until they were detected for the first time in 2011, in the Big Apple, of all places.
A team of scientists led by Rob Dunn from North Carolina State University discovered the first specimens, which the media quickly nicknamed the "ManhattANT".
Since then, numerous researchers, including those from Georgia, have been trying to answer the question: Why does Lasius emarginatus seem to feel so at home in Manhattan, while bucking usual patterns of ant behaviour?
"Most ants that live in cities tend to eat human foods, but it looks like this one doesn't, which is really unique. And if it's not eating human food, what's it eating?" says Kennett, whose wider goal is to discover just what makes these ants so successful.
She has previously researched other ants and also snakes.
"I've always kind of liked working with animals that a lot of people don't really like.
"What fascinates her about ants, she says, is that although they are found all over the world, researchers still don't know everything about them by a long shot. And she loves that ant colonies are mainly made up of females: "A bunch of women running the world is nice."
Lasius emarginatus, however, seem to be very special ants. Sometime between 2006, when a related study failed to detect them, and 2011, when they suddenly appeared in New York, specimens of the species must have emigrated to the US – possibly accidentally by ship.
Lasius emarginatus on a plant in New York. So far, they have been mainly a common species occurring in central and southern Europe, and from Anatolia to the Caucasus. Photo: Samantha Kennett/dpa
"We don't know exactly how they got here, and it's likely we won't be able to answer that fully," says Kennett.
Since then, more and more people in and around New York have reported seeing the ants, with more than 40 responses just on the Project ManhattANT website created by Kennett.
New York, with its many skyscrapers, seems well suited to the ants' way of life, she said.
"They are great climbers," says Kennett, who plans to complete her master's thesis this year. The ants were spotted in apartments on the fifth floor and sometimes even higher.
"As they've become more established in the city, they're just kind of expanding out more."
Lasius emarginatus cannot sting and they are not known to be harmful to humans in any other way, Kennett says. Apparently, they don't even go after people's food waste like other ant species. In Europe, Lasius emarginatus feed mainly on other insects or their excreta, such as the honeydew of aphids.
"And so we think that's probably what they're doing in New York."She can understand New Yorkers don't like to see ants in their homes. But the ManhattANT is completely harmless – and also probably simply impossible to get rid of, she says.
"They're so widespread and it's very hard to completely remove insects once they're here."Originally found in central and southern Europe, the species appears to have embraced the travel opportunities of the modern age.
It has been actively expanding north since 1980, particularly in western Europe. After the first finding in Belgium in 1983, it has colonised the whole country, was found in the Netherlands in 1996 and in England in 2006. – dpa
