Rapid Response Spotted: Invasive Lanternfly

Spotted Laternfly
Photo by Nick Sloff

Penn State researchers and extension educators rapidly respond to the threat of a potential invasive species.

Last September, a state employee in eastern Berks County, Pennsylvania, saw what he thought was a moth hanging out by one of the exterior lights on his back porch. But it was a moth like none he had ever seen—a strong jumper with red and black hind wings and a big yellowish abdomen. He captured it, killed it, and passed it on to a colleague who was traveling to Harrisburg. The insect specimen eventually was delivered to entomologists in the Pennsylvania Department of Agriculture, who confirmed the initial observation: This was no moth. It was the spotted lanternfly, Lycorma delicatula, an invasive species that had recently eaten its way through Korea and, up to this point, had never been observed on U.S. soil.

Greg Hoover’s phone rang a few weeks later. Hoover, an ornamental extension entomologist at Penn State, along with entomologists from the Pennsylvania Department of Agriculture, headed to Berks County—Ground Zero for this new pest invasion. Hoover and the others found adult spotted lanternflies all over the area, but also old egg masses on the trunks of trees. “It hadn’t just arrived,” says Hoover. The insect, it appeared, had been there for at least a year.

Penn State Professor of Entomology Mike Saunders also got a call. He joined a working group in the USDA’s Animal and Plant Health Inspection Service that was chasing down Korean research papers on the spotted lanternfly and getting them translated to get a fix on the potential threat. Native to China, India, and much of Southeast Asia, the spotted lanternfly had reappeared in Korea in 2006—about 70 years after its last reported sighting in the country. “By 2011, it was pretty much all over Korea,” notes Nancy Bosold, a Penn State extension educator who has helped manage public education around the spotted lanternfly.

The papers suggested that the spotted lanternfly wouldn’t be able to handle a rough winter, but the number of adult insects still observed after a particularly harsh southeastern Pennsylvania winter contradicted the reports.

Egg masses
Spotted lanternflies prefer to lay their egg masses on smooth surfaces. Photo by Greg Hoover.

With ongoing translations and ground observations, a fuller picture of the spotted lanternfly began to emerge. It’s a close relative of leafhoppers and planthoppers, but not very mobile. It likely caught a ride over to the U.S. on some international shipment of goods from its native habitat. (“That’s the international economy for you,” says Saunders.) It also likes to feed on the content of phloem cells of plants, using its piercing-sucking mouthparts to snack on the sugars and often excreting “honeydew” onto the host plant, or causing plant sap to flow from feeding wounds. The honeydew is a substrate on which black sooty mold grows that can create black streaks down tree trunks or collect at the base of spotted-lanternfly-infested plants.

“It is not a picky eater and is known to feast on as many as 56 different species,” says Hoover. “Pine trees and peach trees are also preferred host plants—it has a broad palate.”

Its penchant for ornamental plants and grapevines poses a potentially serious economic challenge to the area surrounding Berks County and to Pennsylvania in general. Hoover offers a few stats for context: Pennsylvania ranks fifth among the states in grape production, fifth in apple production, and first in hardwood production.

Spotted laternfly
They are close relatives of leafhoppers and planthoppers, but not very mobile. Photo by Greg Hoover.

So what to do about it? “The Pennsylvania Department of Agriculture’s goal is eradication of this pest,” says Hoover. That path started with the issue of an order of quarantine, focused on six townships and two municipalities, totaling about 30 square kilometers. “That’s the main mode right now,” says Saunders. “We’re doing our best to contain the spread.”

A Christmas tree grower or vineyard owner whose livelihood depends on moving their product off site may wince at the word “quarantine,” and Hoover understands this completely—he used to feel the same way. “Many, many years ago, when I first saw a quarantine, I saw it as this huge wall being built up at a county border not allowing activity to occur,” he says. Now he takes a broader view: If the Pennsylvania Department of Agriculture doesn’t issue an order of quarantine, other states might just prohibit movement of commodities into their state to keep the insect from spreading, increasing the economic losses exponentially.

Bosold, who is working with residents and regulators to relay information about the pest and the quarantine requirements, notes that it was especially important to get an early word out to landscapers, arborists, ornamental nursery owners, tree fruit and grape growers, Christmas tree growers, and the public. “Customers want them to come in and get rid of storm damage, put down new mulch, that sort of thing,” she says. “But under an order of quarantine, they have to leave all that debris in place.” The education extends beyond public PowerPoint presentations, says Bosold, noting they are also taking interested parties to the field to show them spotted lanternfly egg masses.

Engaging the public can help “crowdsource” the observation of the spotted lanternfly, says Hoover. “In most of our detections of invasive exotic pests, observations have been made by homeowners,” he says. “That’s why the education, in my mind, is important not just for all the commodity-related groups but also for the public, so we can have more pairs of eyes picking up more locations.”

So far, says Bosold, public interest has been strong. “Initially, the community was frustrated because they wanted to do something,” she notes. “But there wasn’t always a ready answer.”

Those answers may have to wait until spring. “All we’ve had the opportunity to observe is spotted lanternfly adults feeding and the overwintering egg masses,” says Hoover. “What we need are observations of early and late instar spotted lanternfly nymphs feeding in the area. And you won’t get that until mid- to late May.”

There’s work to be done in the meantime—more research, more requests for funding, more public education—but getting a complete picture of the spotted lanternfly threat requires a “wait and see” mindset, says Saunders. “There are just so many unknowns.”

By Dan Morrell