The leggy bug, a native of China, is an invasive species that first reared its small head in Pennsylvania in 2014, filling U.S. entomologists with alarm. Over the ensuing years, the fly spread along the East Coast, infiltrating New York.
In Virginia near Washington, D.C., I had the pleasure of distance: The insect took some time to get here. Surely, the region saw some spotted lanternflies last year or the year before, but they were relatively sparse.
This summer, however, there has been no escaping the bugs. They’re everywhere, clinging to everything, tenaciously climbing up tall buildings, and heftier than I expected. How are you supposed to kill a bug that’s so large? Others don’t seem to find that a problem, because polka dots of crushed lanternflies now accent the sidewalks in and around D.C.
As the bugs continue to spread, with entomologists predicting that they could reach California within a decade, the situation may feel increasingly hopeless. But there are precautions homeowners can take — and practical things they should know — to help slow the bugs.
Keep an eye out for eggs and nests
Despite its name, the pest is a treehopper bug, so it has more in common with aphids and cicadas than a fly, or even a moth, which its red and gray wings resemble. Even with its wings, the bug itself doesn’t travel far, explained Jacob Leeser of Cornell University’s Integrated Pest Management team. “It’ll travel less than 10 miles a year on its own, but they are very good at hitchhiking. The adults have been tested and can hold on to the windshield of a car going over 50 miles per hour.”
Spotted lanternflies also lay their eggs in brown masses on objects — Leeser pointed to a foldable camp chair as an example, but they're often on trees — which expands their reach, enabling them to spread to 18 states and counting. Keeping an eye out for these masses is essential, he emphasized.
"That's the first thing that we ask all audiences: If you're going on a road trip ... check the bottom of your car for any hitchhikers," Leeser said.
But anyone can do their part to spot and remove the masses between September and May, even if they're staying home.
After you identify a spotted lanternfly egg mass, scrape it off the surface using a rigid piece of plastic and stick it in a container of running alcohol (hand sanitizer works, too), according to Penn State's pest management extension. Alternatively, you can squish the mass; just make sure to do so evenly because the eggs are distributed throughout the mass.
Once the spotted lanternfly establishes itself in a new habitat, the population “grows exponentially,” Leeser laid out. “It’ll take a couple of years, but then they really will be in your face.”
Can spotted lanternflies infest my home?
The spotted lanternflies may be in your face — especially toward the end of July when the adults come into their own — but they won’t be in your home, he reassured. The insects don’t bite, sting or gnaw at millwork, but they are ravenous and need to feed often, he explained. That means it’s unusual for them to survive more than two days inside.
“They’re not going to infest the inside of a home,” Leeser said. “They may come inside, but, within a day or two, they won’t be able to survive inside.”
While the spotted lanternfly is a problem for U.S. agriculture, it’s not the worst inside pest a homeowner could face.
Will a spotted lanternfly harm my garden?
Unless you squash them, the spotted lanternflies will survive in your garden.
They aren’t picky eaters, Leeser noted, although it’s unlikely that the insects will kill a plant even if they’re feeding heavily on it. Grape vines are the exception to that rule; they are the "one agricultural crop that lanternflies will actually kill."
But, if a large number of lanternflies feed in one place — on a grape vine or otherwise — they will leave sugar water in their wake. The sap, called “honeydew,” is something a homeowner might want to deal with, he noted.
“If left on its own, [honeydew] can be kind of sticky, and that would be very attractive to bees or other stinging insects,” Leeser said. “So even though lanternflies aren’t stinging, you may end up with stinging insects coming in to feed on the honeydew.”
It’s easy enough to wash honeydew away with a house, especially considering that the sticky substance can also develop sooty mold if unattended. Although an innocuous fungus, Leeser explained, the mold is unsightly and has the potential to harm plants.
“Let’s say you have some bushes or shrubs underneath the tree that the lanternflies are on,” he suggested. “The honeydew developing sooty mold can kill off that shrub just by blocking photosynthesis.”
Is there spotted lanternfly repellent?
In short, no. Once the lanternflies arrive, keeping them away is difficult.
“We have not had much luck in terms of repellence,” Leeser said.
Researchers have found some evidence that lavender, either as a plant or essential oil, has “a bit of a deterrent effect,” he noted. But a homeowner’s best bet might be making sure a Tree of Heaven plant hasn’t popped up nearby. An invasive species itself, the hydra-like plant is very hard to kill and a favorite food of lanternflies.
Aside from that, Leeser recommends turning to the lanternfly-specific traps that researchers developed over the years, or taking a vacuum to the matter.
“For some small urban gardens in New York City, managers have used a Shop-Vac … to get in and vacuum the insects off the plants,” Leeser said.
Leeser does warn against preventative measures or unsafe management tactics that “could do more harm than the pest itself.” Vinegar treatments will harm other plants without touching lanternflies, and weapons are entirely uncalled for.
“We’ve had people say, ‘Well, I took a flamethrower to that,’” Leeser recalled, referencing social media comments he’s seen over the years.
When it comes down to it, lanternflies will die off for the year once the temperature gets cold, and their population will dip in years to come as natural predators figure out how to eat the invasive bugs. Plus, Leeser emphasized, it’s important to be aware of the “good insects” that are out and about.
“Most insects,” he said, “are beneficial.”