Spotted lanternflies continue to swarm. Don’t expect that to stop anytime soon.

Spotted lanternfly invasion continues

This is what an adult spotted lanternfly looks like with its wings closed. This invasive insect continues to swarm in big numbers in New Jersey, Pennsylvania and other states as autumn gets underway. (Lawrence Barringer | Pennsylvania Department of Agriculture)

If spotted lanternflies are hopping around your patio or landing on your shoulder when you’re working on fall decorations outside your home, don’t expect it to end anytime soon even as temperatures turn colder.

Those pesky insects with colorful wings are still swarming in big numbers in some parts of New Jersey and neighboring states — even flocking to tall buildings in urban areas like Jersey City and New York City. Experts say the swarms will likely continue through most of October and much of November.

The adult lanternflies are just starting the process of mating and laying eggs, and they will continue to do that until the first hard freeze hits.

In New Jersey, that would be a few straight days of temperatures dropping down to 28 degrees or colder — something that usually doesn’t happen until mid-December in most areas of the state.

Even though an extended period of frigid weather will kill the fully-grown spotted lanternflies, experts say most of their eggs that are being deposited on the sides of trees, pallets, firewood, outdoor furniture and other flat objects will survive through the winter season.

Spotted lanternfly invasion

An adult spotted lanternfly with its wings open (top left), an adult spotted lanternfly with its wings closed (bottom left), and a lanternfly egg mass on a tree in Pennsylvania (right). (Submitted | Mass. Introduced Pests Outreach Project)

When the weather gets warmer again next spring, the eggs will hatch and tiny nymphs will eventually grow into adult spotted lanternflies that will be active next summer and fall.

That’s the general life cycle of these invasive insects, which first arrived in the United States in 2012 — apparently on a stone shipment from China — and have now spread to at least 11 states.

Spotted lanternflies feed on the sap on certain types of trees and ornamental plants, but their main targets seem to be the Tree of Heaven, fruits trees and grapevines.

But don’t be surprised if you see these insects swarming on the sides of tall office buildings, blocks away from the lush trees of suburbia. Although research is still being done to determine why spotted lanternflies are attracted to high-rise buildings, experts have some solid theories.

Amy Korman, an entomologist for the Penn State Extension in Lehigh and Northampton counties in Pennsylvania, said spotted lanternflies might be confusing man-made structures for nature’s trees.

“Trees are tall,” she said. “In the spotted lanternfly’s head, they’re going to be attracted to big things. They don’t know the difference. If it’s tall, that maybe translates into food for them.”

Korman said spotted lanternflies aren’t too good at flying (they are better at hopping), so they may be using tall buildings as launching pads to help them move closer to the trees and plants they need to survive.

“When they crawl up the sides of buildings, they use that to launch into the air currents, and that moves them around,” she noted.

Brian Eshenaur, a bug expert at the New York State Integrated Pest Management Program at Cornell University, agrees.

“We know that they crawl up trees and since they are not strong fliers, launch themselves off from the higher positions and glide downward,” Eshenaur said.

“In our urban environment it’s possible they may be confusing tall buildings for very large trees,” he added. “Sometimes dead spotted lanternflies can be found at the bases of tall buildings. This is likely due to the fact that they can only survive for about two days without feeding on a plant.”

Lanternflies aren’t everywhere

Similar to other insect invasions, like the cicadas that were swarming last year, spotted lanternflies vary widely in number from place to place.

“It depends upon what area you are in,” Korman said. “I was in Harrisburg last weekend. They were everywhere — crawling up and down the sides of houses.”

But 90 miles to the east, in the Nazareth area of Northampton County, she wasn’t seeing many spotted lanternflies.

Korman said it’s not unusual to see wide disparities in the numbers, but it’s possible the lanternfly population in the Northampton region was cut down by cool weather during the spring season of 2021.

In New Jersey, spotted lanternflies have been seen in all 21 counties, but the numbers have been considerably lower in Cape May County than in other areas.

In Hudson County, in northeastern New Jersey, big swarms of lanternflies were seen in Jersey City in early August. And on the other side of the Hudson River, these insects have been crawling around on tall buildings in Manhattan in September.

Staten Island has been another hot spot for spotted lanternflies, according to Eshenaur.

Sometimes the numbers change substantially in the same location from week to week, said George Hamilton, an entomologist at Rutgers University.

Hamilton said he was seeing low numbers of lanternflies at a sample site in National Park in Gloucester County, “and then last week I saw more adults than the weeks before then.”

In addition to New York, New Jersey and Pennsylvania, spotted lanternflies have invaded parts of Connecticut, Delaware, Indiana, Maryland, Massachusetts, Michigan, North Carolina, Ohio, Virginia and West Virginia during the past few years, according to data from Cornell University.

Spotted lanternflies in Jersey City

Adult spotted lanternflies on a tree of heaven at The Historic Jersey City and Harsimus Cemetery, Wednesday, Aug. 10, 2022. (Reena Rose Sibayan | The Jersey Journal)

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Len Melisurgo may be reached at LMelisurgo@njadvancemedia.com.

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