Dead grape vines, slick mold, and large-winged, swarming insects have become common sights in southeastern Pennsylvania where the spotted lanternfly has taken over forests, backyards and vineyards.
And with groups of the invasive pest spotted recently in two towns in Fairfield County, the pest could make a significant appearance in Connecticut soon, and researchers haven’t had luck finding a way to stop it once they’ve taken root.
Native to China, India and Vietnam, the first sighting of a spotted lanternfly was in Berks County, Pennsylvania, in 2014. Since then, it has spread and infested most of southeastern Pennsylvania and parts of New Jersey, Delaware and Maryland.
The insects have been known to swarm around people, leave excrement that causes mold growth and attracts insects, stress plants by feeding on them, and even caused widespread death of grape vines.
The spotted lanternfly feeds by sucking out the sap of a variety of trees and plants, but they have favored grape vines during the crucial vineyard harvest season of late summer and early fall, Penn State Extension Associate Heather Leach said.
“You can have as many as 450 lanternflies feeding on a single vine,” Leach said. “So we’re talking about a lot of pressure on these vines, and the growers are having a really hard time controlling them.”
So far, there have been two sightings of groups of spotted lanternfly in Connecticut – in Greenwich and New Canaan, Deputy State Entomologist Victoria Smith said. Smith said those populations have been there for at least a year, but there’s no way to tell for sure.
Smith said the lanternfly is similar to the emerald ash borer because it can fly and spread on its own. That means its spread is likely inevitable, she said.
Efforts to control spotted lanternfly when it has been established in Connecticut will have to focus on controlling local populations to limit damage to crops and trees, she said.
“The number one control option we have is awareness – to let people know what they are, what they look like, and not to move them around,” said Amy Korman, Penn State Extension Educator. “The reason why this insect made its way to Connecticut is because we took it there, it’s a really good hitchhiker.”
The body of the adult spotted lanternfly is about an inch long, with large wings. The front wings are light brown with black sports, and the back wings have patches of red and black separated by a white band. The legs and head are black, and the half-inch wide abdomen is yellow with black bands.
Smith said that anyone spotting a lanternfly in Connecticut should send a picture of it to ReportSLF@ct.gov, and she will review it and respond.
A blight to vineyards and a backyard nuisance
Smith said a major concern over spotted lanternfly spreading into Connecticut is the effect it could have on the wine industry, given its preference for feeding on grape vines and the destruction it causes them.
“Starting in about late August through October is when they are the most prevalent in the vineyards – and by prevalent I mean they’re flying into the vineyards by the hundred, if not thousands, on a pretty regular basis,” Leach said. “And that is unfortunate because that’s when growers are trying to harvest their grapes and start to make their wine.”
Jamie Jones, who owns Jones Family Farms in Shelton, which includes a vineyard and winery, said the spotted lanternfly is something he’s been monitoring for a few years. They haven’t spotted any of the insects on their farm, but it’s something they scout for along with other pests, he said.
“The biggest thing with managing any pest is scouting,” Jones said. “If you just find one, could be you just smush it, otherwise it could take some chemical control.”
Penn State economists estimated in a December 2019 report that the spotted lanternfly is already causing $42.6 million of economic damage a year to Pennsylvania agriculture, mainly in effects to trees, nursery plants and grapes. If the lanternfly spreads across all of Pennsylvania, that damage could be as high as $99 million a year, the report warned.
The lanternfly doesn’t feed on the actual grapes, rather it sucks sap from the trunk or shoots of the vine, Leach said. Over time, that feeding depletes the resources the grapevine needs to survive, which makes it more difficult for the plants to survive over winter and more susceptible to other infections or infestations, she said.
“We’ve seen an eight-and-a-half acre vineyard that was completely destroyed, and another case of a 40-acre vineyard where all the vines died the year after a lanternfly infestation,” Leach said. “Usually this is coupled with other stressors, but we know the damage can be significant.”
There’s also concern about the insects becoming nuisance pets, Smith said. They tend to swarm in their fall mating season, and they excrete a substance called “honeydew” while they feed. The sticky, sugary liquid can spur mold growth and attract other insects like yellowjackets, Korman said.
Leach said nuisance can be an understatement. When you have thousands of insects on a single tree over a deck or car – they’ve counted as many as 13,000 –there will be a growth of “sooty mold” underneath the tree, where the lanternflies drop their excrement.
It’s unpleasant for people, and it causes dieback of undergrowth in the forests, Korman said. Leach said the insects could also cause canopy dieback as trees are stressed by the lanternfly feeding.
One piece of good news is that there doesn’t appear to be tree collapse or death caused by spotted lanternflies, with the exception of the invasive Tree of Heaven, Leach said. It’s especially good news for Connecticut, where about 47 percent of forest trees are considered susceptible to stress from spotted lanternflies, but it doesn’t mean trees won’t be damaged or weakened.
“So in terms of people’s backyard maples and things they want to protect, we’re not seeing tree collapse,” Leach said. “It doesn’t mean the trees are healthy or happy, but tree death is fortunately not as significant as we originally thought.”
Lanternfly is difficult to control
While the lanternfly does show preference for vines holding ripe grapes, it feeds on over 70 varieties of plants and is all across the landscape, Leach said. Even when grape growers are able to control an infestation on their vines, there can be more lanternflies there the next day, Leach said.
“One of the key problems is that they’re so mobile, and you can kill a zillion today, and tomorrow have a zillion more, and that is problematic for a food crop like grapes,” Korman said.
Jones said they have had a few of the invasive Tree of Heaven plants that the lanterfly is attracted to pop up on their farm as a weed, and they’ve done their best to get rid of them. Hopefully, that will make the farm less of a target for the lanternflies in the future, he said.
Their preference for feeding during harvest season can frustrate growers, as well. They have to be careful about when they can use pesticides so close to harvest, Leach said. It’s also expensive and unsustainable to spray pesticides regularly, she said.
Korman said the spotted lanternfly is the strangest insect she’s ever encountered because so little is known about it. The insect has existed in Asia, but there wasn’t much research on it, suggesting that it was never a pest in its native habitat, she said.
“So obviously there were things there that were controlling these populations and holding them in check,” Korman said.
There have been “opportunistic predators” of the lanternflies in Pennsylvania – larger insects, spiders and birds have been seen eating them, but it’s not likely they’ll significantly reduce the population, Leach said.
Penn State researchers have been looking at insects from the native ranges of the spotted lanternfly to see if they could help reduce the populations, but that work is still in the early stages, Leach said.
The best method for holding off the spread of lanternflies into Connecticut is the same as any invasive species – make sure not to carry it in, Korman said. The insect was likely introduced to the U.S. after one laid eggs on packaging that was shipped in, she said.
Jones said it’s important for people to be aware of the insect and be careful not to move it to Connecticut, especially when traveling in infested areas. If someone goes to Pennsylvania to camp, they could bring back an egg mass on extra firewood, or even a lawn chair, he said.
It can travel across states the same way it came into the country – laying it’s mud-like egg masses on any hard surface that are unknowingly carried to a new location. Adult insects can also fly into a car or the bed of a truck and get a ride that way, Korman said.
“I’ve seen where there are a lot of lanternflies, and as people are trying to get into a vehicle, the lantern flies are hopping in the car,” Korman said. “It’s a huge challenge to make sure you’re not carrying eggs or any of the mobile versions around.”