For nearly half a decade, the American public has seen the spotted lanternfly boom in numbers as it spreads to new parts of the country when warm weather returns. Many have held to the "smash on sight" policy urged by public officials to attempt to keep the invasive species at bay and protect vulnerable crops from their damaging effects. Unfortunately, despite everyone’s efforts, it’s becoming even more common to see them clumsily flying about or even landing in a swarm in some places. And now, some researchers say spotted lanternflies are here to stay—and that we should start getting used to their presence.
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Cities could be to blame for the continued spread of spotted lanternflies.
According to a new analysis from a team of scientists at New York University (NYU) recently published in the Biological Journal of the Linnean Society, data shows the deceptively beautiful bugs are now beginning to emerge earlier in the spring and continuing to stay active later into autumn than in previous cycles since its first appearance stateside in 2014.
Since then, the bugs have continued their push from Pennsylvania across an area that now covers most of the U.S. east of the Mississippi River. And while their arrival certainly came at the hands of human activity, research suggests their continued spread is thanks to cities.
“Cities tend to have milder winters, creating favorable conditions for species that otherwise would only be able to live in hot, tropical climates,” Kristin Winchell, PhD, an assistant professor of biology at NYU focusing on ecology and evolution in urban environments, said in a press release. “Cities are also highly connected places where trade happens, and organisms may end up on shipments in planes or boats traveling between cities.”
And as is usually the case with invasive species, there’s also the issue of a missing link in the food chain that could be to blame. “Urban environments aren’t very friendly to a lot of native species, so you have a degraded ecological community that creates opportunities for new species to come in,” Winchell explained.
The team collected their data using input from the public.
Despite the potential difficulties they can cause the agriculture industry, the red lanternfly’s spread has been easy to monitor thanks to its distinctive and admittedly impressive appearance.
Winchell explained that her team used photos uploaded to plant and animal identification community iNaturalist to help collect data on the invasive species’ movement. By analyzing roughly 20,000 photos taken and uploaded between 2014 and 2022, the NYU team was able to spot a trend in which the lanternflies began showing up in earlier uploads each year.
“This is important because a lengthening of the active period every year means they have more time to reproduce and spread,” Winchell said in the release.
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Urban environments could create ideal conditions for the spread of lanternflies.
Researchers point out that higher-than-average temperatures recorded in recent years are also likely playing a part in lanternflies emerging earlier and staying active for longer. However, once the team started measuring where the bugs were spotted in relation to city centers, it became clear that metropolitan areas could be havens for the invasive species.
The team says this might have something to do with the artificially warmer temperatures that are often found in cities thanks to what is known as the urban heat island effect, which might also be helping them brave colder temperatures in northern areas.
But while this might sound like it creates more problems for the continued spread, the data could also help officials more efficiently focus on stopping them in the coming years.
“With spotted lanternflies showing up earlier each year, cities could become early-detection zones,” said Fallon Meng, a PhD student who studies spotted lanternflies in Winchell’s lab. “If people focus on urban areas for routine surveys, this could provide early warnings to new regions and faster response times to potentially limit the spread.”
Lanternflies might naturally begin to decrease in numbers.
However, the data didn’t just show a change in when spotted lanternflies are active. Analysis of photos uploaded to iNaturalist also supported the theory that sightings of the bugs have actually decreased in many of the areas where they were first spotted in Pennsylvania and New Jersey after four to five years of seemingly explosive population growth. Data from the site also showed that since reaching a peak in 2022, New York also appears to have much fewer reported sightings in the past two years.
“This is a classic growth pattern that we see in invasive species as they become part of the ecological community,” said Winchell. “It makes sense that ecological pressures start to knock down the population—for instance, native species like spiders, wasps, and birds are learning to prey on the lanternflies.”
Still, decreasing numbers from initial highs also doesn’t mean nature will take care of them altogether in 2025.
“Will they swarm again like they did a couple of years ago? Probably not,” Winchell said in the press release. “But are they going away? No.”
The takeaway.
Thanks to a new analysis of public-generated data, a team of researchers says the invasive spotted lanternfly is becoming more active earlier and later in the year than previously recorded.
Part of this extension is likely to do with cities, which provide slightly higher temperature zones in which the bugs can reproduce for longer and encourages their spread into new areas. However, this information could help officials more efficiently manage mitigation resources and stop the bugs.
Data also shows that the number of spotted lanternflies is decreasing in places where they were first spotted. The research team says this is likely due to an ecological correction and probably means that while the bugs won’t be going away anytime soon, there will likely be fewer of them over time.
