Spotted lanternflies are in a ‘boom-bust cycle’; what comes next?

HARRISBURG, Pa. (WHTM) — Spotted lanternflies might be entrenched in a “boom-bust cycle” in which their populations will rise and fall in waves, an entomologist says — perhaps never disappearing but just as likely never again quite being the scourge they were a few years ago.

“They’re setting up what is called a boom-bust cycle,” said Anne Johnson, who recently completed her Ph.D in entomology and researches spotted lanternflies at Penn State University. “This is really common in ecology, where you’ll have really high populations one year and they’ll actually use up all the resources in the area, so those populations will kind of collapse. And then once those resources recover, they’ll actually end up going back up again.”

Alas, anecdotally, abc27 News has observed more lanternflies in the Harrisburg area in 2024 than in 2023 although still far fewer than for several years through 2022.

So the big question: Will they ever again “boom” like they did in past years?

“I don’t think we’ll hit the highs that we first hit when they first came into the area,” said Johnson, speaking last weekend at a Hershey Gardens “Bug-o-Rama” event ahead of Penn State’s “Great Insect Fair” this Saturday . “I don’t think they’re ever going to properly go away but we’ll, hopefully, have times when they’re fewer.”

Another piece of good news, which is perhaps contributing to the lanternflies’ relatively modest numbers: Experts feared the invasive lanternflies, which are believed to have traveled from China in cargo shipping containers, would have no predators here. The reality has been more nuanced.

Spotted lanternflies feed on what’s called “tree of heaven,” which is itself an invasive plant species from China and “produces a lot of bitter-tasting toxic compounds,” Johnson explained — which, in turn, make the lanternflies taste bad to would-be predators.

“So a lot of people didn’t think predators were going to be very effective at eating them,” Johnson said.

According to Johnson’s research, a lot of vertebrate predators are deterred by those compounds, but things like spiders and praying mantises are not.

For the latest news, weather, sports, and streaming video, head to WKBN.com.