Wanted-Dead: The Dreaded Spotted Lanternfly

August 12, 2023

By Jeff Wilson–

CJ Reilly and a cadre of “arborists in training” were on a mission. Reilly, Director of Education and Head of Grounds and Operations of the Irvington Woods Park and O’Hara Nature Center, along with student volunteers Sebastien Marcotte, Matthew Besidski and Wilson Lark stood in the wooded park ready to eliminate a cluster of spotted lanternflies or SLFs, an invasive species from Asia feasting on a Tree-of-Heaven (Ailanthus altissima, the SLF’s food of choice.) The troops’ weapon was an industrial-strength shop vac strapped on Lark’s back, reminiscent of a scene from Ghostbusters. Lark flicked the switch and the whirring vacuum went to work, sucking the pesky, destructive critters up and away and curtailing their devastation. They would later be transferred to a plastic bag with a dose of hand sanitizer to exterminate them.

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The doughty defenders had won the battle, but not the war. The bad news is that the SLF, first discovered in Pennsylvania in 2014, is extremely prolific: Reilly’s crew saw only ten to thirty of the insects in 2022; this year, it’s in the hundreds if not thousands. The good news is that the SLF doesn’t actually kill its host trees; rather it “stresses” them, meaning it does its damage by sucking out the tree’s sap and secreting honeydew into the holes it makes, leaving the plant vulnerable to sooty mold (fungi) and other pathogens. And the pest isn’t confined to the woods but has spread to the village, with mold finding its way onto man-made fixtures like patio furniture. “They even jump on cars,” said Reilly.

Reilly and his fellow foresters are fighting back by going after the SLF’s food staple, “removing their preferred host plant – the Tree-of-Heaven” (itself an invasive plant), he stated.

(To compound the problem, however, the insects don’t restrict their diet to the Tree-of- Heaven alone; they also have a taste for wild grape vines and, to a lesser extent, red and silver maple, walnut, sycamore, rose bushes, oak, birch, fruit trees, Virginia creeper, Porcelain berry and others.)

A power vacuum is an efficient harvester of Lanternflies

Sometimes the crew tackles the problem with an electric chainsaw, but more commonly they neutralize the trees by girdling. The boys demonstrated, using a hatchet or chisel to remove a small band of bark encircling the tree like a belt which “suffocates” it and prevents the nutrients – sugars and water – from circulating from the roots to the leaves. While still standing, the tree is barren and thus has no more appeal to hungry SLFs. Homeowners plagued by the pests but lacking a vacuum cleaner can resort to another of Reilly and Company’s methods – squishing the little buggers by hand. “They get tired after about three jumps so are easier to catch,” he noted.

Still Reilly concedes that, as with most invasive species, the chances of total eradication of SLFs are zero – the bugs are here to stay. “We’re trying to mitigate them,” Reilly explained. “We’re never going to get rid of them, so we’re trying to keep their population low.” Neither can the Irvington warriors do it alone. “The SLF is going to be all over the country within the next decade,” Reilly predicted. (A computer map projected on a screen at the O’Hara Center shows the bugs’ spread all over the tri-state area thus far.) And we possibly haven’t seen the worst of the insects’ menace. “A lot of this is very new—how destructive they are or can be to native plants. There’s still a lot to be learned.”

A sea of red on the computer map tells the extent of the infestation nationwide

Marcotte had an additional word to the wise. “Be careful when catching them,” he warned. “They can soil your clothes.”

Sleepy Hollow has also declared war on the Tree-of-Heaven as a way of eliminating the SLF. Trustee Lauren Connell explained that the Village Board has waived the permit requirement for cutting down trees larger than eight inches in diameter in the case of invasive species. “We’re going to send out information with pictures of SLFs and Trees-of-Heaven and letting people know that they don’t need a permit to cut them down, encouraging them to remove them,” she said. But Connell also noted that Trees-of-Heaven are growing everywhere, on public and private property, and that it would take a universal effort to eliminate the trees – and the insects. “One town can’t do it all,” she declared. “The bugs will keep hopping.”

New York State shares the villages’ concerns, encouraging residents to kill SLF egg masses, nymphs and adults. Irvington’s CJ Reilly offers some other tips on how to support the war effort:

• Squish them: Approach them from the back if possible. SLFs get tired after about 3 jumps so are easier to catch.

• Use a vacuum: use a handheld vacuum with a clear, removable canister (not a bag); to prevent spread through waste management, immediately dispose of the SLF from the canister into a sealed ziploc bag with a squirt of hand sanitizer.

• Trap them: Use a wide mouth plastic bottle and seal them in with a shot of water. Tree traps can be purchased or made at home. Install and monitor circle traps on Ailanthus trees. Please AVOID using glue traps as they also kill beneficial insects as well as birds.

• Destroy any Lanterfly egg masses by immediately scraping them into alcohol or hand sanitizer in a sealed ziplock bag. They can be found September to June.

• The Green Policy Task Force is not currently recommending insecticides and herbicides for the control of Spotted Lanternflies. Residents should adhere to Village rules and regulations regarding tree removal and the use of pesticides.

Residents are encouraged to document SLF sightings by joining the “Spotted Lanternfly Watch FLX” group on iNaturalist. Photos should include a scale when possible, such as a coin or ruler.

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