From a distance, the tree trunks appeared to be undulating, as if the bark were rippling in the August breeze. But up close, the source of the movement became clear: hundreds of spotted lanternflies covered the grove of trees at Harford County’s Palmer State Park, rocking from side to side as they slurped sap from the trunks. There were so many bugs that their sugary droppings rained down in a constant fine mist, catching rainbows in the morning sun.

Four years after spotted lanternflies first arrived in Maryland, their population is soaring — and they have stormed into the Baltimore area. The invasive insects, originally from China, are marauding through Harford County playgrounds, lolling in the woods of Baltimore County and plunging their mouthparts into grapevines in Queen Anne’s County. Officials are urging people to kill them and to report them to the Maryland Department of Agriculture so that they can be tracked — even if it is ultimately a futile task.

“We’re really relying on residents to help with this,” said Kenton Sumpter, a Maryland Department of Agriculture entomologist who is leading the agency’s response to the spotted lanternfly.

The number of counties on the state’s spotted lanternfly quarantine list jumped from two to 10 this year in addition to Baltimore City. The agriculture department received nearly three times more reports of the insects from July 12 to Aug. 10 than during the same period last year — 3,159 versus 1,109, Sumpter said. And that’s without reports from Harford and Cecil counties, where the bugs have become so ubiquitous that officials are no longer asking for reports of them.

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Translucent gray with a blush of pink, the spotted lanternflies are eating their way across the state like giddy tourists. As they feed on more than 70 species of plants, they have little to worry about from natural predators, except for the occasional ambitious praying mantis or curious Labrador retriever.

The insects are largely harmless to humans; they don’t sting or bite or carry diseases. But — again, like tourists — they are fond of the state’s vineyards. The tiny tipplers love to suck sap from grapevines and hop vines, weakening the plants and forcing farmers to invest time and money to control them. Plus, the sugary substance they excrete, optimistically named “honeydew,” attracts a dark, blotchy fungus called sooty mold, further damaging plants. The tiny creatures pose a threat to the state’s $2.6 billion wine industry.

“Vineyards have been getting hit very hard, especially in Cecil and Harford” counties, said Sumpter. “This is the first year that we’ve been told they have lost a volume of crop to the spotted lanternfly.”

Despite their bad habits, the insects at first glance are rather charming. Their outermost wings are translucent gray and covered in what look like tiny ink spatters. Beneath that is a set of brown and white wings. The innermost layer is bright red with black polka dots; the effect is of a person in a prim gray suit wearing garish underwear. These red wings serve an important purpose. Lanternflies flash them at predators as if to say, “Don’t eat me. I taste like crap.”

The first spotted lanternflies apparently sneaked into the United States about a decade ago, hiding out on a shipment of rocks delivered to Berks County in southeastern Pennsylvania. (The stinkbug, another invasive pest, is also believed to have entered this country in Pennsylvania by way of a Chinese shipping container.)

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Since their arrival, spotted lanternflies have fanned out through the mid-Atlantic states and beyond, popping up in Delaware, Virginia, West Virginia, New Jersey, New York, Connecticut, Massachusetts and, of course, Maryland, where they first appeared in 2018. There are smaller populations of the creatures in seven other states.

Spotted lanternflies fly awkwardly, as if they are continually surprised to discover they have wings. They are planthoppers, flicking themselves from one branch to another. They excel at hitching rides on cars, trucks and trains, Sumpter said, making them most prevalent along transportation corridors. “They will stick to a train until it hits its destination,” he said. In 2018, the United States Department of Agriculture started spraying insecticide on trucks at Interstate 95 rest stops to stop the critters from passing through or leaving Maryland, Sumpter said. But that program ceased with the advent of the pandemic in 2020. Today, the insects are so widespread in Maryland that little can be done to stop them.

“They’re hard to catch, they’re really fast and they breed like crazy,” Sumpter said. “At a certain point, we just have to coexist with them because we can’t spray them all.” Yet he urged residents to engage in the Sisyphean task of killing and reporting them. It’s especially important to prevent them from moving to new regions, which is why Sumpter’s department recently moved swiftly to kill a colony of the bugs near Baltimore-Washington International Airport. The bugs could hop a plane to just about anywhere.

“I would hate to be responsible for the loss of the central [wine] valleys in California,” Sumpter said. “There would be a lot of people mad at me.”

Tony Fiore, operations manager of Fiore Winery in the village of Street in Harford County, is seeing firsthand the effect of spotted lanternflies on his vineyards. The first bug appeared last August, and soon he was finding as many as 10 on each vine at his family’s meticulously maintained 10-acre vineyard.

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This year, the insects are even more prevalent, Fiore said. On a sunny August day, the long lines of grapevines stretching across the hills of the winery looked like an Impressionist landscape. But up close, spotted lanternflies paraded among the glowing pale green grapes. While the insects rarely kill a host plant outright, they can weaken them, making them more likely to die in a hard winter.

Fiore said he lost one vine last year to the pests, but he is concerned he will lose more this year. Already, he has spent several hundred dollars on additional pesticide applications, and he is planning to encase the vines in large nets to keep the spotted lanternflies out. Since the bugs become more active in early fall, the time of year when grapes are harvested, workers will need to inspect the picked grapes to ensure that no bugs topple into the winemaking process.

While the bugs have been abundant in Harford and Cecil counties for the past couple years, they have become easier to spot in other parts of the state this year. Baltimore City and its surrounding counties, as well as Frederick and Montgomery counties, were added to the state’s spotted lanternfly quarantine list this year. That means that businesses moving plants, landscaping materials and certain other items must receive a permit and inspect their vehicles to ensure lanternflies or their eggs aren’t hitching a ride.

Gardeners, hikers and those who spend a lot of time outside have been spotting the pests for the first time in recent weeks. Vanessa Beauchamp, a Towson University biology professor, saw her first one in late July at the university’s Monkton field station. Beauchamp and her students tried to squash it, but the bug was too quick. “I’ve been on the lookout for them for two years, but this was the first time I’ve seen one,” she said.

A few days later, Beauchamp and her research team saw several dozen spotted lanternflies feeding on one of their favorite food sources, the invasive ailanthus tree, also known as tree of heaven. Americans imported the tree of heaven from Asia in the 1800s, thinking the quick-growing trees would complement their gardens. However, the trees soon dominated nearly every green space, like a real life “Little Shop of Horrors.” For nearly 200 years, the tree of heaven has grown aggressively, taking over parks and empty lots and even sprouting from vacant buildings. But now their old nemesis from Asia has found them: the spotted lanternfly.

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The spotted lanternfly loves nothing more than slipping its mouthparts into the bark of the tree of heaven, its preferred food back home. The tree has a bitter taste that the insects absorb, making them less appealing to predators. Kenton said its unclear whether spotted lanternflies could kill trees of heaven, but it wouldn’t be a bad thing if they did, since the invasive trees push out native species.

At Palmer State Park last week, so many lanternflies clustered in a stand of trees of heaven that the air shimmered with honeydew. Sumpter explained that as the insects suck sap out of plants, excess sugar and water build up in their bodies until it explodes out of their backsides. “Don’t open your mouth when you look up,” he said, gazing warily at the mist.

The bottoms of trees and surrounding vegetation shone with a thick layer of honeydew and were darkened by sooty mold. Bees and wasps lingered in the honeydew, which they use as a food source. Some Pennsylvania beekeepers have been marketing honeydew honey, which has a dark, smoky taste, but others say the bees’ new indulgence has ruined the crop of honey.

Jay Falstad, the executive director of the Queen Anne’s Conservation Association, also saw his first spotted lanternflies in recent weeks after years of looking for them. The bugs were scooting on a grapevine on Falstad’s small farm in northern Queen Anne’s County near Unicorn Lake.

“It looks like they’re starting to proliferate in a major way,” said Falstad, a state master naturalist. “It’s important for everyone to try to kill them. It’s probably a losing battle, but we need to put up a long fight.”

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Falstad finds the most effective way to catch the bugs is to hold an open wide-mouthed water bottle near them. The bugs jump in, but can’t figure out how to get out. He also finds it easier to squish them at night by flashlight than during the day. And, he said, he’s noticed that even during the day, the bugs lose their mojo after their third or fourth hop, becoming easier to whack.

Sumpter prefers to smack the bugs with the brim of his baseball cap. Fly swatters work well, he said, but the best way to kill a large group is to suck them up with a backpack-style vacuum.

The bugs will be especially active in the coming months, chugging sap, eyeing up mates and laying their egg cases, which resemble smears of gray putty. (People should scrape those off and throw them away, too.) Adults will die off during the first deep freeze, but the eggs will persist. In late spring, new juvenile spotted lanternflies will scuttle out, hungry and eager to find their place in this new world.

julie.scharper@thebaltimorebanner.com

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