Spotted lanternflies are bad because they are voracious, indiscriminate feeders that drain the sap from dozens of plant species, excrete massive amounts of sticky waste that fosters destructive mold, threaten vineyards and hardwood forests, and spread with alarming efficiency by hitchhiking on cars and trains. Native to China, they were first detected in the United States in 2014 and have since turned into one of the country’s most visible invasive pest problems, prompting state governments to literally ask residents to stomp them on sight. The damage they cause is real, but also more nuanced than a simple “they kill everything they touch.”
How They Feed and Why It Hurts
Spotted lanternflies are phloem feeders. They use piercing mouthparts to tap into the tissue that transports sugars and nutrients through a plant’s vascular system. Think of it as the insect equivalent of jabbing a straw into the plant’s circulatory system and drinking continuously. A few lanternflies on a branch do relatively little harm. The trouble starts when populations build up, which they do readily. Research on grapevines found that low densities of four or fewer lanternflies per shoot had minimal effects, but once numbers climbed to eight or more per shoot, the insects drained enough sugar to induce carbon limitation in the vine, depleting starch reserves in the roots and potentially setting the plant up for poor growth the following season.1PubMed Central. Prolonged phloem feeding by the spotted lanternfly, an invasive planthopper, alters resource allocation and inhibits gas exchange in grapevines
This is a critical distinction. Spotted lanternflies don’t chew leaves or bore into wood the way some pests do. They quietly siphon resources, and the damage accumulates over time. A vine or tree that loses its belowground starch reserves heading into winter may leaf out weakly the next spring, produce less fruit, or become vulnerable to secondary stresses like drought or disease. The worst-case scenario is death, but that typically requires sustained heavy feeding over multiple seasons rather than a single bad year.
The Honeydew and Sooty Mold Problem
Every drop of phloem sap a spotted lanternfly drinks passes through its body, and much of it exits as a sugary excretion called honeydew. When populations are dense, the honeydew falls in a constant drizzle, coating leaves, branches, sidewalks, cars, outdoor furniture, and anything else below the feeding site.2PubMed. Perspective: shedding light on spotted lanternfly impacts in the USA That sticky film is more than an annoyance. It serves as a growth medium for sooty mold, a dark fungal coating that turns surfaces black. On leaves, sooty mold blocks sunlight and reduces photosynthesis, compounding the stress that feeding already causes. On understory plants that never had a single lanternfly touch them, the mold alone can weaken growth simply because they sit beneath a heavily infested tree.3Environmental Entomology. Distribution, Survival, and Development of Spotted Lanternfly on Host Plants Found in North America
For homeowners, the nuisance factor is hard to overstate. In heavily infested areas, decks and patios become unusable, and the sheer volume of lanternflies swarming and aggregating on outdoor surfaces interferes with everyday life. The insects breed, feed, and gather in massive numbers, turning backyards into something out of a low-budget horror film.3Environmental Entomology. Distribution, Survival, and Development of Spotted Lanternfly on Host Plants Found in North America
Vineyards Are the Hardest Hit
Of all the industries affected by spotted lanternflies, grape production has taken the biggest blow. Vineyards are especially vulnerable because grapevines are preferred hosts and because the economic margins in wine and table grape production leave little room for crop loss. In Pennsylvania, where the initial U.S. population established itself, some growers experienced losses severe enough that they had to replant entire vineyards due to vine death caused by lanternfly feeding.4Journal of Integrated Pest Management. Assessing the potential economic impacts of spotted lanternfly (Hemiptera: Fulgoridae) infestations on grape production in New York State The combination of direct sap loss, honeydew-driven sooty mold, and reduced root starch creates a cascade of problems that weakens vines season after season.
Grapevines also mount their own defense when heavily infested. Research shows that prolonged feeding by ten to fifteen lanternflies per vine triggers a suite of systemic responses, including increased production of defensive compounds like phenolics and changes in enzyme activity. These defenses appear to reduce the plant’s suitability as a host over time, but they come at a metabolic cost to the vine, diverting energy away from fruit production and growth.5PubMed Central. Spotted Lanternfly Feeding Induces Systemic Defense Responses in Grapevines So even when the vine fights back, it pays a price.
Not Just Grapes, and Not Always Catastrophic
Spotted lanternflies feed on more than 70 plant species, including fruit trees, ornamental trees, hardwoods, vines, and shrubs. Their known host range keeps expanding as the insects colonize new territory and encounter species they haven’t been tested against before.3Environmental Entomology. Distribution, Survival, and Development of Spotted Lanternfly on Host Plants Found in North America Among their most notable hosts are maples, black walnut, birch, willow, and hops, in addition to grape. The breadth of this list is part of what makes the insect so concerning: it can find something to eat almost anywhere in the eastern U.S. landscape.
That said, the severity of damage in forests and urban landscapes is less clear-cut than in vineyards. A four-year study that confined lanternflies to the same trees for consecutive growing seasons found measurable harm, but the researchers noted that this represented a worst-case scenario. In the wild, lanternfly populations on individual trees fluctuate from year to year, and the insects move among hosts frequently. The negative impacts on forest and ornamental trees in natural settings would not be expected to match those extreme conditions.6PubMed. Effects of long-term feeding by spotted lanternfly (Hemiptera: Fulgoridae) on ecophysiology of common hardwood host trees This is worth keeping in mind when reading alarming headlines: the pest is genuinely destructive, but the worst outcomes require sustained, high-density populations on the same plants year after year.
The Tree-of-Heaven Connection
One of the stranger chapters in the spotted lanternfly story involves tree-of-heaven (Ailanthus altissima), itself an invasive species from the same part of the world. Spotted lanternflies show a strong preference for tree-of-heaven, and all life stages can be found on it. For years, researchers speculated that the insects might not be able to complete their life cycle without access to this tree. That turned out to be wrong. In 2019, experiments confirmed that lanternflies can develop and reproduce on other hardwood hosts, though their fitness drops when tree-of-heaven is absent, with dramatically fewer egg masses laid.7PubMed Central. Performance and host association of spotted lanternfly (Lycorma delicatula) among common woody ornamentals
This matters for management. Some early strategies focused on removing tree-of-heaven to deprive lanternflies of their preferred host, and that approach can reduce local population fitness. But it is not a silver bullet. The insects will survive and breed on alternatives, just less productively. Managers need to account for the possibility that even in areas without tree-of-heaven, lanternfly populations can persist on native hardwoods.
The relationship with tree-of-heaven also gives spotted lanternflies an unusual form of chemical protection. Tree-of-heaven produces toxic compounds called quassinoids, and lanternflies that feed on it sequester those chemicals in their own tissues, particularly their salivary glands. Research suggests this sequestration provides some defense against bird predators, essentially borrowing the tree’s toxicity as personal armor.8PubMed Central. Sequestration of plant defenses by spotted lanternfly (Lycorma delicatula) and effects on avian predators In other words, the invasive tree makes the invasive insect harder to kill naturally.
Why They Spread So Fast
Spotted lanternflies are not strong fliers. Adults can hop and glide, but they do not migrate long distances under their own power. Their spectacular spread across the eastern United States is overwhelmingly driven by hitchhiking on human transportation. Females lay egg masses on nearly any flat surface, including shipping containers, pallets, vehicles, stone, and outdoor equipment. Those egg masses can travel hundreds of miles before anyone notices them.
Adults hitchhike too. Experimental work has shown that all mobile life stages of the lanternfly can cling to the exterior of a vehicle traveling at highway speeds. Roughly 30 percent of all tested insects remained attached when exposed to wind speeds of about 100 kilometers per hour, and the most favorable attachment points on vehicles, like wiper blades and the scuttle panel, allowed insects to withstand average dislodgement speeds above 80 kilometers per hour.9PubMed Central. Experimental evidence supports the ability of spotted lanternfly to hitchhike on vehicle exteriors as a mechanism for anthropogenic dispersal Given the insect’s ability to travel more than 150 kilometers in single jumps, likely by riding on cars, trucks, and trains, the potential for long-distance dispersal is enormous.10Scientific Reports. Human-mediated dispersal drives the spread of the spotted lanternfly (Lycorma delicatula)
This human-assisted movement is why quarantine zones and “check before you travel” campaigns are central to the management effort. The insect did not walk from Pennsylvania to New York or Virginia. People drove it there, unknowingly, on their cars and cargo.
Where They Came From and Where They’re Going
Spotted lanternflies are native to China. They invaded South Korea (first detected in 2006), Japan (2009), and the United States (2014).11Population Ecology. Evaluating the origin and spread of spotted lanternfly (Lycorma delicatula) in Japan Genetic analysis traced the U.S. population to a single introduction event, with South Korea serving as the intermediate source. South Korea essentially acted as a stepping stone, or “bridgehead,” in the insect’s global invasion history.12PubMed Central. Global phylogeography and invasion history of the spotted lanternfly revealed by mitochondrial phylogenomics The fact that the entire U.S. population traces back to a single event, with the lowest genetic diversity of any known population, means that all the damage so far came from one boatload of stowaways, probably on a shipment of stone or goods into Berks County, Pennsylvania.
Climate modeling suggests the insect could expand well beyond its current range. Warmer winters, in particular, are predicted to reduce egg mortality, potentially allowing populations to survive farther north and at higher elevations than they currently do.13PubMed Central. Real-Time Integrative Mapping of the Phenology and Climatic Suitability for the Spotted Lanternfly, Lycorma delicatula Australia and Europe have also been flagged as regions with suitable climate for establishment, though neither has reported populations yet.14Biological Invasions. Mapping the life-history, development, and survival of spotted lantern fly in occupied and uninvaded ranges
Why Natural Predators Haven’t Solved the Problem
In their native range in China, spotted lanternflies are kept in check by a combination of parasitoid wasps, predators, and environmental pressures that have co-evolved with them. In North America, those natural controls are largely absent. Some generalist predators like spiders, praying mantises, and certain birds do eat lanternflies, but the feeding pressure is nowhere near enough to control large populations. The chemical defense lanternflies acquire from tree-of-heaven adds another layer of protection: birds that try to eat them may find them unpalatable or mildly toxic, discouraging repeat predation.8PubMed Central. Sequestration of plant defenses by spotted lanternfly (Lycorma delicatula) and effects on avian predators
One bright spot is the accumulation of native fungal pathogens that have begun infecting lanternflies in the wild. Researchers have documented at least sixteen species of insect-killing fungi attacking the pest, with Beauveria bassiana being the most common.15PubMed Central. Accumulation of Fungal Pathogens Infecting the Invasive Spotted Lanternfly, Lycorma delicatula Lab and field trials have shown that applications of B. bassiana and a related fungus, Isaria fumosorosea, have potential for controlling high-density lanternfly populations in vineyards and semi-natural landscapes with minimal risk to non-target organisms.16Environmental Entomology. Applications of Beauveria bassiana (Hypocreales: Cordycipitaceae) to Control Populations of Spotted Lanternfly (Hemiptera: Fulgoridae), in Semi-Natural Landscapes and on Grapevines But these biological controls are still in development, not yet deployed at the scale needed to make a landscape-level difference.
The Management Dilemma
Chemical insecticides remain the frontline tool for controlling spotted lanternflies, and they work. Dinotefuran, a neonicotinoid, has proven highly effective in field trials, suppressing lanternfly numbers for three to five weeks after application with no observable negative effects on non-target arthropods like bees or parasitoid wasps in the treated plots.17Journal of Economic Entomology. Efficacy and nontarget effects of broadcast treatments to manage spotted lanternfly (Hemiptera: Fulgoridae) nymphs However, the picture is more complicated at a broader scale. Neonicotinoids are systemic, meaning they can be taken up by the treated tree and appear in its flowers. When tree-of-heaven or red maple blooms after a neonicotinoid treatment, pollinators visiting those flowers may be exposed to residues.18The Great Lakes Entomologist. Insect Floral Visitors of Red Maple and Tree-of-Heaven at Potential Risk of Neonicotinoid Residue Exposure from Spotted Lanternfly Control
This creates a genuine tension: the most effective tool for protecting grapes and trees from one invasive insect could pose risks to the native bees and beneficial insects that pollinate crops and wildflowers. Managers increasingly look at integrated approaches, combining targeted chemical treatments during the nymph stage (when lanternflies are most concentrated and vulnerable), biological control agents like fungal sprays, physical methods like sticky bands on tree trunks, and habitat management that reduces tree-of-heaven availability. None of these alone is sufficient. Together, they offer the best chance of keeping populations manageable without creating collateral damage.
The “Kill on Sight” Campaigns
Few invasive species have inspired the kind of public mobilization that spotted lanternflies have. State agriculture departments across the Mid-Atlantic have run campaigns encouraging residents to stomp, squash, and report the insects. Pennsylvania’s department has urged people to “Kill it! Squash it, smash it… just get rid of it,” while New Jersey’s slogan is “Join the battle, beat the bug!” Some residents have taken creative approaches, including modifying vacuum cleaners to suck up lanternflies in bulk, though the occasional use of flamethrowers has been officially discouraged.19American Entomologist. The Forgotten War Against the Fly
Does stomping actually help? At a population level, probably not much. Spotted lanternfly populations can reach densities where individual killing makes no meaningful dent. But the campaigns serve an important secondary purpose: they keep people aware of the insect, encourage reporting of new sightings at the edges of the invasion front, and remind travelers to check their vehicles and outdoor gear for egg masses. The real value of public engagement is not in the boots doing the stomping but in the eyes doing the looking, catching new infestations early before they become entrenched.
For homeowners dealing with lanternflies on their property, practical steps include scraping egg masses off outdoor surfaces during winter and early spring (the putty-colored patches look like smears of mud and are easy to overlook), wrapping tree trunks with sticky bands to trap nymphs as they climb, and contacting local extension offices for guidance on targeted insecticide applications. If you are in an area where lanternflies have recently appeared for the first time, reporting the sighting to your state agriculture department is probably the most impactful thing you can do. Early detection at the invasion front is where management dollars go the furthest.