In summer, spotted lanternflies (Lycorma delicatula) appear in clusters on street trees and building facades throughout New York, Seoul, and Shanghai. Despite their cute name, they are pests that suck sap and cause sooty mold with their secretions, damaging fruit trees. They look like cicadas, but their wings are gray or brown and opaque. When the forewings open, 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 the answer. They said the species did not randomly wander into cities from forests; rather, it succeeded in big cities because it came to the United States already adapted to urban environments in its native China. In other words, big cities are not only gateways for nonnative species but also "evolutionary incubators" that cultivate them to flourish where people live.
◇ Urban spotted lanternflies' unique genes identified
Over the past 10 or so years, 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 major cities in the northeastern United States 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 genetically closer to urban populations in Shanghai than to rural and forest populations there.
For example, in spotted lanternflies from U.S. cities and central Shanghai, notable changes appeared in genes related to detoxification, stress response, and metabolism. The researchers said this was "a result of adaptation to urban environments," adding, "These genes likely helped the lanternfly adapt to city environments long before it arrived in the United States."
Comparing the genomes of Shanghai's urban and forest populations, the team reported clear signs of natural selection in genomic regions tied 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 varied host plants—before arriving in the United States.
The researchers also found that U.S. lanternfly populations are not genetically diverse. That indicates a genetic "bottleneck" that occurs when a small number arrive in a new area, found a colony, and then rapidly expand. The team detected evidence of three bottlenecks in the U.S. lanternfly genomes. A bottleneck about 171 years ago aligns with Shanghai's urbanization period, while bottlenecks about 30 years ago and 9 years ago correspond to the times of introduction to Korea and the United States, respectively. This genetically supports the invasion route in which part of the Shanghai urban population moved to the United States via Korea.
In Korea, the spotted lanternfly was sighted once in 1979, then not seen until it reappeared in Cheonan, South Chungcheong Province, in 2005. It drew public attention in 2006 when numbers surged in Cheonan and on Gwanaksan Mountain in Seoul. Based on genetic traits, the populations that emerged domestically are thought to have originated in China. The government designated the species as an ecosystem-disrupting organism in 2013. The lanternfly is known to damage more than 40 kinds of fruit trees, including grapevines.
◇ European ants that took over Manhattan in 10 years
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 spotted lanternflies in U.S. urban areas grow larger than their rural counterparts. The team said larger body size allows 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 nonnative insect that has settled in big cities with a different look than before. In 2011, an unfamiliar ant was found in flower beds on the medians of Broadway at 63rd and 76th streets in Manhattan, New York. It matched none of the roughly 800 ant species native to North America. Robert Dunn of North Carolina State University, who first found it, temporarily nicknamed it the "ManhattAnt."
Dunn and Clint Penick of Auburn University reported in 2024 in the journal Biological Invasions that, after comparing the ManhattAnt's DNA with ant DNA in databases worldwide, it proved to be the Lasius emarginatus, a species native to central Europe. Lasius emarginatus has a black head and abdomen and a reddish thorax. Worker body length is 3–5.5 mm.
Although Lasius emarginatus is not dominant anywhere in Europe, in Manhattan it expanded its range by 2 kilometers a year. Penick said, "In 10 years, this ant has nearly taken over Manhattan," adding it is "the second most common species after Tetramorium immigrans, which has lived in New York for a century."
The ManhattAnt has already spread to New Jersey and Long Island. At the current pace, it is expected to push north to Maine and south to Georgia. The researchers said its success stems from adaptation to urban environments. The ManhattAnt monopolized honeydew secreted by aphids, scale insects, and spotted lanternflies living on street trees. While other ants foraged only on the ground, the ManhattAnt went upward.
Scientists warned that if the ManhattAnt, adapted to big cities, spreads along road networks like the spotted lanternfly, it could harm native ecosystems. Benoit Guénard of the University of Hong Kong said, "Invasive species that seemed trivial for decades can suddenly explode and cause serious problems."
The Asian needle ant that arrived in the United States from Asia in the 1930s is a representative example. Also called the Asian needle ant, this nonnative species was not considered a threat until 20 years ago, but it has recently advanced into forests and is wiping out native ants that help disperse plant seeds.
The stories of the spotted lanternfly and the ManhattAnt show that to see the future of nonnative species, we must look to cities as well as forests and farmland. Cities are gates through which invaders enter and, at the same time, 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
Biological Invasions (2024), DOI: https://doi.org/10.1007/s10530-024-03344-z