In summer, spotted lanternflies (Lycorma delicatula) appear in clusters on street trees and building facades across New York, Seoul, and Shanghai. Despite their cute name, spotted lanternflies are pests that suck sap and cause sooty mold with their excretions, damaging fruit trees. They look like cicadas, but their wings are gray or brown and opaque. When they spread their forewings, the red hindwings appear, which is why they are called scarlet-winged spotted lanternflies.
How can spotted lanternflies thrive even in major cities? U.S. scientists analyzed the insect's genes and found an answer. They say the insects did not simply stray into cities from forests; they succeeded in big cities because they had already adapted to urban environments in China, where they originally lived, before arriving in the United States. In other words, metropolises are not just gateways for invasive species but have become "incubators of evolution" that raise them to flourish where people live.
◇Distinct urban spotted lanternfly genes identified
Over the past decade, the spotted lanternfly has become the most prominent invasive species in the United States. First detected near Philadelphia, Pennsylvania, in 2014, it spread north to New York, Baltimore, and Boston, and west to Detroit and Chicago. It moved along the U.S. road network into major cities.
A team led by Kristin Winchell, a biology professor at New York University, collected 98 spotted lanternflies from northeastern U.S. cities and 20 from Shanghai, China, and analyzed their genes. According to a paper published in Feb., in Proceedings of the Royal Society B, U.S. lanternflies were closer to urban populations in Shanghai than to rural or forest populations.
For example, in spotted lanternflies from U.S. metropolises and central Shanghai, distinct changes appeared in genes related to detoxification, stress response, and metabolism. The team said, "This is the result of the lanternfly adapting to urban environments," adding, "These genes likely helped it adapt to urban environments long before it arrived in the United States."
Comparing the genomes of Shanghai's urban and forest populations, the researchers found clear signatures of natural selection in genomic regions related to detoxification, stress response, and metabolism in the urban group. This suggests the lanternfly may have adapted to urban conditions—such as pesticides, heat islands, and diverse host plants—before reaching the United States.
The team also found that U.S. lanternfly populations are not genetically diverse. This is a genetic "bottleneck" that occurs when a small number of individuals colonize a new area and then expand rapidly. The researchers identified evidence of three bottlenecks in U.S. lanternfly genomes. A bottleneck about 171 years ago coincides with Shanghai's urbanization, while those about 30 years ago and 9 years ago align with the timing of introduction to Korea and the United States, respectively. This genetically supports an invasion route in which part of the Shanghai urban population crossed to the United States via Korea.
In Korea, the spotted lanternfly was seen once in 1979 and then not again until it reappeared in 2005 in Cheonan, South Chungcheong Province. The population surged in 2006 in Cheonan and on Gwanaksan Mountain in Seoul, bringing public attention. Based on genetic traits, the lanternflies that appeared domestically are presumed to have originated in China. The government designated the insect an ecosystem-disturbing species in 2013. The lanternfly is known to damage more than 40 kinds of fruit trees, including grapevines.
◇European ants that took over Manhattan in a decade
The spotted lanternfly did not stop evolving after arriving in the United States. A team led by Brenna Levine of Kean University reported last year in the journal Integrative and Comparative Biology that urban U.S. lanternflies grow larger than their rural counterparts. The team said larger body size enables them to store more energy to withstand the high temperatures caused by urban heat islands and potentially travel farther to other major cities.
There is another invasive insect that settled in a different form in a metropolis. In 2011, an unfamiliar ant was found in the flower beds of the median strips on Broadway at 63rd and 76th streets in Manhattan, New York. None of the more than 800 native North American ant species matched. The discoverer, Robert Dunn of North Carolina State University, temporarily nicknamed it the "ManhattAnt."
Dunn and Clint Penick of Auburn University reported in 2024 in the journal Biol Invasions that DNA from the Manhattan ant matched Lasius emarginatus, a species native to central Europe, when compared with ant DNA databases worldwide. Lasius emarginatus has a black head and abdomen and a red thorax. Worker ants measure 3 to 5.5 mm in body length.
Although Lasius emarginatus is not dominant anywhere in Europe, it has expanded its range by 2 km a year in Manhattan. Penick said, "This ant has almost taken over Manhattan in a decade," adding, "It is the second most common species in New York, after Tetramorium immigrans, which has lived there for a century."
The Manhattan ant has already spread to New Jersey and Long Island. At the current pace, it is expected to expand north to Maine and south to Georgia. The researchers said the Manhattan ant's success stems from adapting to urban environments. The species appears to have monopolized honeydew secreted by aphids, scale insects, and spotted lanternflies living on street trees. While other ants foraged only on the ground, the Manhattan ant went upward.
Scientists worry that if the urban-adapted Manhattan ant spreads along road networks like the spotted lanternfly, it could harm native ecosystems. Benoit Guénard of the University of Hong Kong said, "An invasive species that seemed trivial for decades can suddenly surge and cause serious problems."
The Asian needle ant that arrived in the United States from Asia in the 1930s is a representative case. Also known as the Asian needle ant, this invasive species was not considered threatening until 20 years ago, but it has recently advanced into forests and is wiping out native ants that help disperse plant seeds.
The cases of the spotted lanternfly and the Manhattan ant show that to foresee the future of invasive species, we must look not only at forests and farmland but also at cities. Cities are both gateways for invasives and evolutionary laboratories that select invaders strong in human environments.
References
Proceedings of the Royal Society B (2026), DOI: https://doi.org/10.1098/rspb.2025.2292
Integrative and Comparative Biology (2025), DOI: https://doi.org/10.1093/icb/icaf013
Biol Invasions (2024), DOI: https://doi.org/10.1007/s10530-024-03344-z