Spotted Lanternflies Make Presence Known

By Richard Smith l August 5, 2021

Was it a happy case of “No news is good news?” The spotted lanternfly, an invasive insect accidentally introduced from China into Eastern Pennsylvania in 2014, became established by 2018 in New Jersey and other neighboring states.

Last year, it became all-too-noticeable here in Somerset County and sections of neighboring Mercer last year. (“Spotted Lanternflies Are Here – Scientists expect $400 million in damage to trees, landscape and agriculture annually in the Garden State,” The Montgomery News, September 2020). Vigorous countermeasures followed: focused spraying programs by state and federal departments of agriculture (especially in vineyards whose succulent grapes are prime targets of the insatiable plant juice- and fluid-drinking pests); citizen initiatives to destroy both adults and egg masses found on trees (and even on houses and automobiles); and voluntary removal by property owners of “tree of heaven,” which spotted lanternfly especially light upon during their reproductive cycles.

Spotted Lanternfly nymphs on a sumac tree in Griggstown in July.

As a result – or so it seemed – there was a reassuring lack of spotted lanternfly reports this spring from the general public. But, that was only the proverbial lull before a major storm. Now, the numbers of spotted lanternfly nymphs have seemingly exploded, with disturbingly visible tree swarms in parks and on private land.

According to Prof. George Hamilton, extension specialist in pest management at the Rutgers School of Environmental and Biological Sciences, scientific investigations have documented that “the numbers are larger than last year.” How could hordes of spotted lanternflies have evaded notice by most property owners and park users?

These insects, Prof. Hamilton explains, develop through four distinct “instar” larval stages, between which they molt and become progressively larger. The younger juveniles are better camouflaged, black with small white spots. But the final instar sports a bright red back, progenitor of the red wing-band display characteristic of the adults.

Two stages of Spotted Lanternfly nymphs

The 2021 season is providing more ominous data. “We feel they’re developing faster through the stages,” Prof. Hamilton says. “It’s mainly temperature-related. The warmer it is, the faster they go through the nymph instars.” By the time this issue of The Montgomery News is published, the adults will almost certainly have fully emerged. It might seem puzzling that an insect known as a “plant hopper” – with limited flight ability but adept at leaping away from a swatter or onto a succulent tree, vegetable or fruit – has managed to infest 11 states, from West Virginia to, most recently, Connecticut. All in seven short years. How?

The spotted lanternfly is an opportunistic hitchhiker. Indeed, it’s believed that spotted lanternflies first arrived in America in 2014, having entered an equipment crate that was subsequently shipped from eastern China to Berks County, Pennsylvania. Populations were quickly established in neighboring Bucks County, then the creatures vaulted the Delaware River as if it were only a trickle. Last summer, they were documented as having infested eastern Mercer County and the whole of Somerset. Urban asphalt and concrete are no deterrent: Clusters of nymphs are now coating park trees in Jersey City, North Bergen, Kearny, and other Hudson County communities. And if they aren’t already sunning themselves on the Jersey Shore, they’ve likely made their reservations for Summer 2022.

Adult Spotted Lanternfly

The spotted lanternfly (scientific name, Lycorma delicatula) is not poisonous. Nor does it bite or sting. But it feeds on the fluids of at least 70 varieties of trees and other plants. Not surprisingly, grapes are immediately targeted wherever available. If enough lanternflies feed on grape vines, the plants wither and die. Close by, multitudinous lanternfly nymphs have been documented in Montgomery, Rocky Hill, Skillman, Belle Mead, Griggstown, and Hillsborough. Montgomery Township administrator Donato Nieman says: “We’re reporting the infestations to the state’s Forestry Management Services and encouraging property owners to kill as many of them on their land as possible, as we’ve been instructed to do.”

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Nieman emphasizes that Montgomery is not under-reacting to the problem by awaiting state action. Any use of toxic agents must be carefully coordinated by state and local governments, especially on public lands. “There’s always been a concern about using pesticides and potentially exposing people who are using the park to these chemicals,” he says. Montgomery has been prioritizing integrated pest management, says Nieman, including use of organic treatments whenever possible.

An integrated approach is also the strategy of Unionville Vineyards, the Ringoes-based winery and event center which has extensive grape plantings near Great Road. General manager John Cifelli reports a resurgence this year of voracious Japanese beetles, a bane to both hobbyist gardeners and commercial farmers. Employing the integrated care concept, Unionville Vineyards is scheduling a rare pesticide spraying for when both beetles and lanternflies will be at their most exposed and vulnerable. The lanternfly threat is “still in a manageable shape,” says Cifelli, noting, “This year, the state is doing some really great work for us.”

One effective N. J. Department of Agriculture strategy involves cone-shaped mesh traps secured to the sides of trees containing spotted lanternflies. These traps capture nymphs or adults which, after flying or falling down, are climbing back to their high sanctuaries. No adhesives are involved, so the traps are harmless to birds. “They’ve caught hundreds of lanternflies already,” Cifelli says.

Another simple but highly promising tactic involves erecting barriers of special 4-foot-high netting between the grapevines and tree lines harboring the invaders. Leaving the trees, lanternflies will flit or hop towards the succulent fruit. They can easily climb the nets – but the material is embedded with a chemical that kills them shortly after contact. So, this insecticide can be used effectively without being sprayed into the environment. “Last year we evaluated one material, with EPA approval, and this year we will be treating two other types of netting with the same goal,” says Prof. Nielsen. “We are still in an experimental phase, but the idea is that dispersal by spotted lanternfly into vineyards will be reduced with the combination of a physical barrier and a toxicant.”

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There have been recent reports of lanternflies falling to predators already natural to America, with some news sites touting praying mantises as actively feasting on the pests. But Prof. Hamilton warns, “As a rule we don’t recommend people buy or release praying mantises. They are generalist predators and will eat any insect they can catch, including beneficials.” Aware of possible unintended ecological disruptions when other species are mobilized in the fight against invasive insects, specialists from the USDA’s Agricultural Plant Health Inspection Services (APHIS) are doing active but cautious field studies in China.

Should they identify predators of the spotted lanternfly in its native environment, live specimens will be brought to the United States. But, Prof. Ferguson says, “kept in strict quarantine while they’re being studied. So, if they’re released, they won’t become a problem themselves.” Prof. Ferguson urges citizens to join the fight against the lanternflies. “If they continue to kill them whenever they see them, that’s about all we can do right now,” adding, “I’m hesitant to recommend spraying in suburban areas because the houses are so close together.” “The stage we’re really concerned about is the adults,” he says. “They are mobile and will fly into an area. They’re bigger, they consume more, and they move towards grapes and other fruits and vegetables.” The “Tree of Heaven” (Ailanthus altissima, commonly known in China as chouchun) is greatly favored by these pests, both in North America and their native East Asia.

“If you have them on your own property, you can remove them,” says Prof. Ferguson. “It will definitely help. But it won’t completely solve the problem because they feed on other trees and plants.” Over the winter, New Jersey and Federal agriculture department teams applied anti-lanternfly treatments to some 20,000 woodland acres in our state. And the state budget for fiscal year 2022 has $500,000 directly allocated for spotted lanternfly control. By next summer, we’ll likely know if such efforts and funding were enough.

For detailed information on the Spotted Lanternfly and its control:

To report spotted lanternfly infestations to the N.J. Dept. of Agriculture (after killing as many of the pests as possible) go to badbug.nj.gov, click on the spotted lanternfly photo and fill out a sighting form. You may also call 833-4BADBUG (833.422.3284) or email SLF-plantindustry@ag.nj.gov.