What Does Spotted Lanternfly Damage Look Like?

Spotted lanternfly damage shows up in several distinct ways, and the most immediately obvious sign is often not on the plant itself but on it and beneath it: a sticky, glistening coating of honeydew that darkens into black sooty mold. The insects feed by piercing bark and stems to tap into the plant’s sugar-rich phloem, and the waste they excrete attracts fungal growth that can coat leaves, trunks, and even nearby surfaces like patio furniture and cars. Beyond that visible mess, affected plants show wilting, reduced growth, bark weeping, and in severe cases, dieback of branches or entire vines. The damage varies widely depending on the plant species and how many lanternflies are feeding, which makes identification trickier than it first appears.

Honeydew and Sooty Mold Are the First Things You Notice

Before you see a single wilted leaf, you will probably notice the honeydew. Spotted lanternflies are messy eaters. As they feed on phloem sap, they excrete large quantities of a sugary liquid that coats everything below and around the feeding site. Fresh honeydew looks like a shiny, wet glaze on leaves, bark, and the ground. It feels sticky to the touch and attracts ants, wasps, and other sugar-loving insects in large numbers. If you find a tree trunk or vine that looks like someone poured syrup down it, honeydew is the likely culprit.

Within days, a dark fungus called sooty mold begins colonizing the honeydew. This turns affected surfaces gray to black, giving leaves and bark a dirty, charcoal-dusted appearance. The mold itself does not directly parasitize plant tissue, but it creates a physical barrier over leaf surfaces that blocks sunlight. Research measuring this effect found that light reaching a leaf dropped by about 0.36% for every 1% increase in sooty mold coverage, which adds up quickly when mold covers most of a leaf’s surface.¹ Less light means less photosynthesis, compounding the stress the plant is already under from losing sap.

The sooty mold does not stay neatly on the host tree, either. It accumulates on understory plants growing beneath infested trees, meaning ground-level vegetation can look blackened even if no lanternflies are feeding on it directly. The accumulation tends to be heaviest near the trunk and decreases toward the outer edge of the canopy, though it varies considerably from tree to tree.¹ If you are walking through a wooded area and notice that low-growing plants beneath certain trees are coated in a black film while plants a few feet away look fine, that pattern is a strong indicator of lanternfly activity overhead.

Bark Weeping and Wound Sites on Trunks

Another telltale sign is weeping sap from the bark of trees. Spotted lanternflies tend to congregate in large groups on trunks and major limbs, and their feeding punctures can cause sap to ooze from the bark surface. These weeping wounds often look like wet, dark streaks running down the trunk. The sap itself ferments, producing a sour, vinegar-like smell that is distinctive enough to help you identify a heavily infested tree even before you see the insects. On smooth-barked trees, the weeping trails are especially visible and can attract additional insects to the fermented sap.

The wounds themselves are not large or dramatic to the eye. You will not see gouged bark or obvious holes the way you might with a wood-boring beetle. Lanternfly mouthparts are piercing-sucking structures that create tiny punctures, so the physical wound is small. What makes the damage visible is the volume of sap that leaks and the sheer number of feeding sites when populations are high. A heavily infested tree can have dozens of weeping spots, giving the trunk a wet, streaked appearance that looks alarming even though no single wound is mechanically devastating.

What Grapevines Look Like Under Heavy Feeding

Grapevines are among the most visibly and physiologically affected hosts. Vineyards in infested areas have reported some of the most dramatic damage since the spotted lanternfly arrived in the United States in 2014. The visible signs on grapevines include wilting leaves, stunted shoot growth, and premature leaf drop. In severe infestations, entire vine canopies can look thin and sparse by late summer, when they should be at peak fullness.

Underneath the surface-level appearance, what is happening is a drain on the vine’s energy reserves. Research on two grape species found that when feeding densities were low (around four or fewer lanternflies per shoot), the vines showed minimal measurable effects. But as densities climbed to five or more per shoot, the impact on the vine’s internal carbohydrate and nitrogen balance became increasingly severe. At high densities of eight or more per shoot, the feeding was intense enough to substantially reduce leaf gas exchange and deplete starch reserves in woody roots.² Starch in roots matters because it is the energy a vine draws on to survive winter and push out new growth in spring. Depleted roots mean the vine may look fine at the end of one season but come back weak the next year, or fail to leaf out at all.

For grape growers, this creates a particularly frustrating pattern. A vine subjected to heavy late-season feeding might still produce fruit that year, but the real damage only becomes apparent the following spring when buds fail to break or new shoots are stunted. The researchers concluded that intensive late-season feeding by large adult populations can induce a kind of carbon starvation, with the potential for lingering effects in subsequent years when root reserves have been severely drained.² So the damage to grapevines is not always what you see today but what you discover months later.

Hardwood Trees Show Slower, Subtler Decline

On large shade and forest trees, spotted lanternfly damage is harder to spot than on grapevines, partly because trees have far larger energy reserves and can absorb more feeding pressure before visibly declining. But the damage accumulates. A study tracking feeding effects on silver maple, weeping willow, river birch, and tree of heaven over four consecutive seasons found that prolonged infestation significantly reduced trunk diameter growth and depleted starch stored in roots, and that these effects scaled with the number of lanternflies present.³

What does this look like in your yard or neighborhood? In the first year or two of infestation, you might not notice anything beyond the honeydew and sooty mold. The tree’s canopy may appear normal. Over time, though, infested trees start to look thinner. Branch dieback begins at the tips, the canopy lets more light through than it used to, and leaves may appear smaller or slightly off-color. The same multi-year study found that by the second year, leaves on all four tree species showed reduced levels of iron, sulfur, and phosphorus compared to uninfested controls.³ Those nutrients are critical for photosynthesis and growth, so their decline helps explain the gradual thinning and reduced vigor that homeowners eventually notice.

Tree of heaven, the spotted lanternfly’s preferred host, is an invasive species itself and not one most people are trying to protect. But the lanternfly readily feeds on dozens of native hardwood species, including maples, oaks, walnuts, birches, and willows. The visual damage pattern on these native trees tends to follow the same trajectory: honeydew and sooty mold first, then gradually declining canopy health over multiple seasons if the insect population is not managed.

Fruit Trees Fare Better Than You Might Expect

Given how severe the damage can be on grapevines, you might assume apple and peach orchards are in serious trouble too. The evidence so far suggests otherwise. A study examining young apple and peach trees exposed to spotted lanternfly feeding across an entire season found that apple trees showed no significant differences in health between infested and uninfested groups, either during the exposure period or afterward.⁴

Peach trees showed some effects during infestation by early-stage nymphs, including a temporary reduction in trunk diameter growth. Infested peach trees also had more frost damage to buds the following spring, suggesting some depletion of cold hardiness reserves. But the longer-term measurements found no lasting impacts on growth or physiology, and the researchers concluded that the spotted lanternfly is unlikely to be a major threat to these deciduous fruit crops.⁴ This does not mean you will not see honeydew and sooty mold on fruit trees; you almost certainly will in infested areas. But the tree itself is more likely to shrug off the feeding than a grapevine would.

This finding matters for homeowners who panic after finding lanternflies on their backyard apple or peach tree. The cosmetic mess of honeydew and sooty mold can look alarming, but the tree’s underlying health is probably not in serious jeopardy from the feeding alone. That said, the sooty mold on fruit itself is a quality issue: nobody wants to harvest apples coated in black fungus, even if the tree is healthy.

How to Tell Spotted Lanternfly Damage from Other Problems

Several other pests and diseases can produce symptoms that overlap with spotted lanternfly damage, and misidentification is common. Aphids, scale insects, and planthoppers all excrete honeydew that leads to sooty mold, so black-coated leaves alone are not proof of lanternfly activity. The key differentiators are scale and context. Spotted lanternfly infestations tend to produce far more honeydew than most other sap-feeders because the insects are large, gregarious, and feed in dense aggregations. If the sooty mold extends well beyond the tree canopy onto nearby surfaces, walkways, and vehicles, the volume of honeydew is more consistent with lanternflies than with aphids.

Another clue is timing. Adult spotted lanternflies are most active and visible from late July through November, and the heaviest honeydew production coincides with the adult stage in late summer and fall. If you are finding fresh, sticky honeydew on outdoor surfaces in September and October, lanternflies are a strong suspect. Aphid honeydew, by contrast, tends to peak earlier in the growing season.

The insects themselves are distinctive enough to confirm the identification. Nymphs go through several stages: early nymphs are small and black with white spots, later nymphs are red with white and black spots, and adults have grayish forewings with black spots and vivid red hindwings visible in flight. Egg masses, laid in fall, look like smears of gray-brown putty on smooth surfaces such as tree bark, stone, outdoor furniture, and vehicles. Finding egg masses or the insects at any life stage alongside the sooty mold and honeydew confirms the source.

Wilting and dieback in grapevines can also be caused by fungal diseases like powdery mildew, downy mildew, or trunk diseases such as Eutypa dieback. The difference is that lanternfly-induced decline is accompanied by the characteristic honeydew mess and tends to worsen in proportion to visible insect populations, whereas fungal diseases show lesions, discoloration, or fuzzy growth on leaf surfaces and stems without the sticky residue.

Damage You Cannot See Right Away

Some of the most consequential damage from spotted lanternfly feeding is invisible during the season it occurs. As noted in the grapevine research, root starch depletion can take months to express itself. A tree or vine that looks passable in October might fail to break dormancy properly the following spring. For perennial plants like grapevines and young trees, the year-after effects can be worse than the current-season symptoms because the plant has lost the energy reserves it needs to recover from winter, push new growth, and resist late frosts.

This delayed damage is especially important for vineyard managers and landscapers who need to decide whether intervention is necessary. A vine that still has green leaves and is carrying fruit in September might look like it is coping, but if lanternfly densities have been high for weeks, the root system may already be severely depleted. Waiting for obvious canopy collapse before acting can mean the intervention comes too late to save the vine’s productivity the following year.

What the Damage Means on Non-Plant Surfaces

Spotted lanternfly damage is not limited to living plants. The honeydew that rains down from infested trees lands on anything underneath: cars, decks, patio furniture, playground equipment, and building siding. The fresh honeydew is merely sticky and annoying, but once sooty mold colonizes it, the black residue can stain porous surfaces like wood and concrete. Outdoor dining areas beneath infested trees become unusable during peak feeding season. Pools and water features collect honeydew, promoting algae growth and making water maintenance harder.

On vehicles, the honeydew and mold combination can etch clear coat finishes if left for extended periods, similar to the damage caused by tree sap or bird droppings. The fermented honeydew can also attract yellowjackets and other stinging insects in large numbers, creating a secondary nuisance and safety concern for anyone spending time outdoors near infested trees. Homeowners in heavily infested areas sometimes describe their outdoor living spaces as essentially off-limits from August through October.

The Role of Host Preference in Where Damage Shows Up

Spotted lanternflies feed on more than 70 plant species, but they do not damage all of them equally. Tree of heaven is a strong magnet, and in mixed landscapes, lanternflies often congregate heavily on tree of heaven while leaving nearby species less affected. Removing tree of heaven from a property can sometimes redistribute feeding pressure onto other plants, which is worth considering before cutting down every tree of heaven you find. Some land managers use tree of heaven strategically as “trap trees,” treating them with systemic insecticide so that lanternflies feeding on them are killed.

Grapevines, as discussed, are among the most vulnerable agricultural crops. Hops, another crop with thin, flexible stems and accessible phloem, have also drawn concern from growers, though published research on hops damage is still limited compared to grapes. Among ornamental plants, black walnut, river birch, and various maples are commonly fed upon and can show significant canopy decline over multiple years of infestation.

One pattern that catches homeowners off guard is the lanternfly’s attraction to smooth-barked trees. Young trees with thin bark are easier to feed on than mature trees with deeply furrowed bark, so recently planted landscape trees can take a disproportionate hit. A newly planted maple in its first or second year may suffer more visible stress than a mature maple next to it, simply because the young tree’s bark offers easier access and the tree has fewer energy reserves to absorb the loss.