Surge in sex-crazed, crop-destroying spotted lanternflies expected this year after population plunge

They bugged off — and now they’re back in full force!

A huge uptick in sex-crazed, crop-destroying spotted lanternflies is expected to swarm the Big Apple after a population plunge last year  — and they’re already hatching in droves, experts told The Post Wednesday.

An egg count taken this past winter at a vineyard in Berks County, Pennsylvania — considered “ground zero” for the invasive pest — showed roughly 1,700 egg masses per row compared to nearly none the previous year, said Kelli Hoover, professor of entomology at Penn State.

A rise in sex-crazed, crop-destroying spotted lanternflies is expected to swarm New York City. Christopher Sadowski

“It was almost nothing and then — boom — now they’re back in big numbers,” Hoover said. “It’s a huge increase.”

The red-and-tan-winged insects — which recklessly munch through everything from vegetable gardens to fruit trees — began hatching last week in areas in and around New York City, experts said.

The tiny invaders made their buzz-worthy arrival two weeks earlier than usual, likely due to heat from a warm spring trapped by buildings in the urban jungle, said Jacob Leeser, of Cornell University’s New York State Integrated Pest Management Program.

While the spotted lanternfly population appeared to drop in the city after spikes in 2022 and 2023, their apparent disappearance could be a sign they’ll be back in full force this year.

The insects may have “boom and bust cycles” because they gobble up their main food source —  a leafy green plant known as the Tree of Heaven — one year, leaving them with nothing to eat the next.

“It’s like everybody getting to the salad at the same time,” Leeser said. “As the availability of food starts to fall, the population does too.” 

Last winter’s egg population study, led by Penn State University researcher Brian Walsh, is the biggest reason New Yorkers might want to brace for another invasion this year, Hoover said.

Jacob Leeser, of Cornell University’s New York State Integrated Pest Management Program, said the insects arrived two weeks earlier than usual due to the rise in heat from a warmer spring climate. Christopher Sadowski

“It may be a boom cycle but it’s really hard to predict,” she said. 

The insects — which start off as black and white nymphs that jump — generally hatch in late May, and people tend to notice them while they are frantically mating in August, Leeser said.

New Yorkers have in past years waged a war to squish away the lusty red, black and white lanternflies — but they may be best extinguished with a simple household appliance, he said. 

To kill them, Leeser recommended New Yorkers drag their vacuum cleaners outside to patios, balconies or yards to suck up the moth-sized bugs.  

But be sure to wait 48 hours before emptying the vacuum bag, to ensure they don’t reemerge, he warned.

Research also shows the bugs can’t live inside apartments for more than 50 hours because they can’t survive on house plants, which is good news to most New Yorkers, he added.

Meanwhile, Trees of Heaven must be sprayed with herbicide months before they can be chopped, making the insects’ meal of choice hard to remove, experts said.

Lanternflies, which grow to roughly an inch long, first arrived in the Big Apple 2020 from southeast Asia.

The bugs have recently spread like wildfire — to a total 18 states —  and entomologists are trying like crazy to stop them from getting to lucrative wine country in California, Hoover said.

“They’re hopping on train, planes, ships and other transportation,” she said. 

“These guys are brave hitch-hikers.”