Spotted lanternflies gather on trees to feed on sap, and they can do so in stunning numbers. These invasive insects, first found in Pennsylvania in 2014, feed on at least 70 tree species, though their strongest preference is for tree-of-heaven, an invasive tree also native to China. If you’re seeing clusters of colorful insects on your tree trunks and branches, here’s what you need to know about identifying them, understanding the damage, and taking action.
Which Trees They Prefer
Tree-of-heaven is by far the most attractive host. Spotted lanternflies that feed on it have higher survival rates, and females produce significantly more eggs compared to those feeding on other species. But these insects are not picky. Maples, black walnut, birch, willow, and grapevines are all common targets. They’ll also feed on fruit trees like apple and stone fruits. If you have a tree-of-heaven on or near your property, it’s essentially a magnet for lanternfly populations.
Younger nymphs (the early life stages) tend to feed on soft, new shoots of various plants. The older, larger nymphs and adults have stronger mouthparts that can pierce directly into the bark and woody tissue of mature trees. This means you may notice the smaller black-and-white nymphs on younger growth in spring, then see the larger red nymphs and winged adults clustered on tree trunks later in summer.
What They Look Like Through the Year
Spotted lanternflies go through distinct stages, and knowing the timeline helps you act at the right moment. Egg masses appear on tree trunks and outdoor surfaces from September through June. They look like grayish splotches of mud or putty, roughly 1.5 inches long and 3/4 inch wide, and are often found on the underside of branches or flat surfaces.
Nymphs hatch in May. The early nymphs, active from May through July, are small (about 1/4 inch), black with white spots. By July, they molt into a striking red-and-white stage, roughly 3/4 inch long, that lasts through mid-August. Adults start appearing in July and persist through December. They have gray wings with black spots and a flash of bright red on the hind wings when they fly or jump. Egg-laying runs from September through November, or until the first hard freeze kills the adults.
How They Damage Trees
Spotted lanternflies are sap feeders. They pierce bark and stems with needle-like mouthparts and consume large quantities of sugary sap to extract the nitrogen and amino acids they need. Because the sap is mostly sugar water, they expel huge volumes of excess liquid called honeydew. This honeydew coats leaves, branches, and anything beneath an infested tree.
Left to accumulate, honeydew becomes a growth medium for sooty mold, a dark fungal coating that blocks sunlight from reaching leaf surfaces. This reduces a tree’s ability to photosynthesize. Honeydew also ferments and produces a distinctive sour smell that attracts bees, wasps, and other nuisance insects to the area.
The feeding itself depletes a tree’s stored energy reserves and starches. Heavy infestations can cause individual branches to die back and reduce overall photosynthesis. Trees already stressed by drought, disease, or other factors are especially vulnerable. That said, most established trees are not killed outright. Penn State Extension notes that heavy feeding has contributed to the death of grapevines, tree-of-heaven, and black walnut saplings, but for other tree species, the damage is better described as chronic stress rather than a death sentence. Grapevines and fruit crops face additional economic harm because sooty mold on fruit skins makes them unmarketable.
Scraping Egg Masses
The simplest thing you can do is destroy egg masses before they hatch. Late fall through early spring, after freezing temperatures kill the adults but before eggs hatch in May, is the ideal window. Check tree trunks, branches, rocks, outdoor furniture, fences, and any hard surface. The egg masses blend in easily, looking like dried mud, so inspect carefully, including the undersides of branches.
Scrape them off with a flat, hard edge (a putty knife, old credit card, or paint scraper works well) into a resealable bag containing rubbing alcohol or hand sanitizer. Seal the bag and dispose of it. Simply knocking egg masses to the ground won’t kill them. You need to crush, drown in alcohol, or burn the eggs to be sure.
Tree Banding and Traps
Traps placed on tree trunks take advantage of the lanternfly’s habit of walking up and down the bark. Two main types work well, and both should be in place by early May to catch nymphs as they emerge.
- Sticky bands wrap around the trunk and catch insects as they climb. Place them about four feet from the base. The critical caveat: unprotected sticky bands also trap birds, beneficial insects, and small animals. Always install a barrier above the band, such as a piece of vinyl window screening secured at the top with push pins and flared outward at the bottom, several inches below the sticky surface. You can also use chicken wire caging around the band or a narrower strip to reduce unintended catches. Check bands at least once a week.
- Circle traps use screening that encircles the trunk and funnels climbing lanternflies upward into a container they can’t escape. These are more wildlife-friendly than sticky bands and don’t require the same precautions, though they still need regular emptying.
If you find a bird or animal stuck to a sticky band, don’t try to free it yourself. Take the band to a local wildlife rehabilitation center.
Chemical Treatment Options
For high-value trees with heavy infestations, systemic insecticides offer the most targeted protection. These are absorbed into the tree’s tissue, so lanternflies die after feeding. Two common active ingredients are used: one acts quickly (effective within 24 hours when injected into the trunk) and is best applied from July through September. The other works more slowly and is typically applied as a soil drench after flowering through July. A licensed arborist or landscape professional can determine which method suits your situation.
Application methods include trunk injection, trunk spray (sometimes called bark banding), and soil drenching. Trunk injection provides the fastest results, while soil drenches take longer because the chemical must travel up through the root system. Contact sprays that kill insects on the surface are also effective but should only be applied after blooming finishes to protect pollinators like bees.
For a less intensive approach, horticultural oils, insecticidal soaps, and neem oil can kill lanternflies on contact, though they won’t provide lasting protection the way systemic treatments do.
Natural Enemies and Biological Control
Native fungi are emerging as a promising check on lanternfly populations. A naturally occurring fungus called Beauveria bassiana was found killing adult lanternflies in Pennsylvania as early as 2017. Researchers have since identified 20 different strains of this fungus infecting lanternflies across southeastern Pennsylvania, with three strains appearing at most field sites. In field trials, a commercially available spray containing this fungus killed 43 to 48 percent of nymphs and adults on infested trees.
At least three other native fungal species have also been found attacking lanternflies in the wild. These natural infections tend to spike in fall when adult populations are dense, creating localized die-offs. While fungi alone won’t eliminate an infestation, they contribute real pressure on lanternfly numbers without chemical intervention. Researchers noted that some of the same fungi can also infect other insects, including yellowjacket wasps drawn to honeydew beneath infested trees.
Where Lanternflies Have Spread
The first U.S. infestation was discovered in Berks County, Pennsylvania, in 2014, likely arriving on a stone shipment from China around 2012. Despite quarantine efforts, the insect has proven difficult to contain. It has spread to multiple states across the Northeast and Mid-Atlantic, with populations confirmed in New York, New Jersey, Virginia, Maryland, Delaware, Connecticut, Massachusetts, Indiana, and others. Quarantine measures have slowed the spread but not stopped it.
Lanternflies are excellent hitchhikers. Egg masses laid on vehicles, shipping containers, firewood, and outdoor equipment travel long distances before anyone notices them. Many early detections in new states were traced to individual egg masses or dead adults that arrived on transported goods rather than natural flight. If you live in or travel through an area with known populations, checking your vehicle and outdoor gear before leaving is one of the most effective ways to prevent new infestations from establishing elsewhere.