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The Drought May Temporarily Slow the Lanternfly Invasion, Home-made Traps Will Help

By Richard D. Smith | August 27, 2022

Mottos and slogans promoted by environmental and agricultural agencies carry the urgency of wartime mobilization: “Join the Battle, Beat the Bug,“Stomp It Out!,” “If You See It, Squash It!”. And for citizens driving out of officially quarantined high infestation counties, there’s a plea to Look Before You Leaveby examining vehicle wheel wells and undercarriages.

Mike Van Clef directs invasive species responses for the non-profit Friends of Hopewell Valley Open Space, headquartered in Titusville. Spotted lanternflies, says Van Clef, “crossed the Delaware several years ago and it seems that they have reached all corners of New Jersey. It's possible the populations will continue to increase...”

This summer’s hot, drought-level conditions might have reduced the numbers of lanternflies surviving into the adult stage. But he cautions against early optimism: “Bugs often have great years and less great years in cycles.”

George C. Hamilton of the Department of Entomology, Rutgers New Brunswick, and an Agricultural Extension specialist in pest management, says that although high numbers of spotted lanternfly nymphs were found this spring at a research sampling site in southern New Jersey “that has steadily declined throughout the summer to the point that [during the last sampling] we only found 11 adults. I would guess higher ... temperatures the last month or so are responsible for the apparent population suppression.”

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The spotted lanternflies’ unquenchable thirst for plant fluids and their fearsome fertility bring dread to farmers and vintners who face devastation of their tomatoes, succulent vegetables, and especially grapes. Lanternflies drain the grapes until even the vines die, and have been described as “looking burned to the ground.”

Unionville Vineyards, based in Ringoes, has extensive Montgomery-area grape plantings on Province Line Road and Great Road. Right now, says General Manager John Cifelli, there’s a suspenseful pause in the 2022 lanternfly campaign. Rutgers experts have advised him that the adult lanternflies are “still high in the tree canopies and will be coming down soon as the nutrient flow within trees and vines and other plants changes and preferred host plants change.”

Yet in the face of an inevitable lanternfly onslaught, Cifelli remains committed to minimizing pesticides. Timing is vital. “At Unionville we continue to limit insecticide usage as much as possible, and time our sprays to affect pests that affect us in overlapping timeframes,” he says.

Property owners are finding the creatures abundant on certain shrubs and trees, especially maples and the “Tree of Heaven” (itself an invasive species and a preferred site for lanternfly feeding and breeding).

Strategies for controlling these invasive species

While squashing them helps, it is minimal at best. What can property owners do now at summer's end to control these invaders? Not all effective methods are recommended. For example, sticky tape traps also kill birds, beneficial insects, squirrels, and bats.

“I would agree that the sticky bands are ... not the best thing to use,” Professor Hamilton says. “Circle traps might be a better choice.”

Circle traps are basically funnels, which lanternflies can enter but not leave. They can be made or purchased (see resources section at the end of this article). “We have a grad student in the department looking their effectiveness. It’s too early to tell how good they are at reducing populations but she is catching large numbers in her study. I would use them on trees where lanternflies are congregating or moving up and down the trunks.”

Professor Hamilton adds: ”Insecticides are also effective but we don’t recommend that homeowners spray every tree on their property. Just ones that are being attacked, especially if adults are congregating on the lower trunk and branches that can be easily reached. If they want the whole tree sprayed, they should hire a professional to do so.

“They also need to consider what they use.” He recommends against neonicotinoid insecticides, which contain chemicals similar to nicotine, “because of their systemic nature that can carry over to the following spring, potentially impacting beneficial pollinators.”

Cutting down tree of heaven growths remains an option “if you can afford it,” says Prof. Hamilton. “I don’t recommend that homeowners attempt to fell big trees because of the potential danger involved.”

Despite the impact — figuratively and literally — that stomping on individual spotted lanternflies can have (and the satisfactions it can bring – see sidebar article), Dr. Van Clef doesn’t prioritize this grassroots and sidewalk level approach to SLF control.

“While I appreciate the campaigns to squish bugs or scrape-off egg cases,” he says,”it will not be successful. For example, many cases are located high up in trees. We've suggested that people get rid of their Tree of Heaven that the bugs particularly enjoy eating and congregating on.

“I’m not sure we can actually kill enough of the trees to make a wider impact, but it may help. At the very least, it locally stops the honeydew [lanternfly secretions] that grow a black sooty mold on everything down below.”

The spotted lanternfly (scientific name Lycorma delicatula), originated in southeastern China and adjacent regions of Asia. It’s a “leaf hopper” insect whose propensity to hide in vehicles and freight shipments has enabled it to jump not merely plant to plant but country to country. The first spotted lanternflies in the U.S. are believed to have arrived around 2014 in a crate of equipment or specialty stone sent to Berks County, Pennsylvania.

In the absence of known major predators, lanternflies then radiated outward to at least 12 eastern states. And there’s no sign of them stopping. They’re New Jersey-wide, and not only in rural, shore and suburban areas: Video footage taken in early August documented hordes of spotted lanternflies inexplicably swarming against new high-rise buildings in Jersey City.

Links to more information:

For homeowners:
For business owners:
About circle traps:

About the "Invasive Species Strike Team" of the Friends of Hopewell Valley Open Space:


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