Where Do Lantern Flies Go at Night?

Spotted lanternflies spend most of the night clinging to tree trunks, clustered in groups on the lower and middle portions of the trunk rather than out on branches or in flight. They are primarily daytime feeders and movers, so once the sun sets they tend to settle into these resting positions and stay put until morning. But “resting” does not mean invisible, and understanding their nighttime habits opens up some practical opportunities for dealing with them.

They Roost on Tree Trunks, Not in the Canopy

If you go outside after dark with a flashlight and check the trees in your yard, you will likely find spotted lanternflies gathered on the trunk itself rather than up in the leaves. Research on adults living on tree of heaven, their preferred host, found that far more individuals occupied the lower and middle trunk sections than the branches. Specifically, over a thousand adults were counted on the middle trunk and hundreds more on the lower trunk, while the upper branches held far fewer, dropping to double digits on the second branch level and above.¹ This trunk-hugging pattern holds throughout the day but becomes especially pronounced at night, when the insects stop moving between feeding sites and settle in place.

This makes intuitive sense. Spotted lanternflies are sap feeders. During daylight hours, they move along branches and onto leaves to find phloem, the sugar-rich fluid that flows through plant tissue. At night, without the warmth and light cues that stimulate activity, they drift back toward the trunk or simply stay wherever they last fed. Trunks offer a broad, stable surface to grip with their tarsal claws, and clustering in groups may provide some passive protection through sheer numbers.

Do They Fly After Dark

Spotted lanternflies are not strong fliers even during the day. Their flight tends to be short and somewhat clumsy, more of a powered glide than a sustained aerial trip. Research on adult females found that spontaneous flights averaged about 24 meters, with a typical range of 10 to 50 meters, and that heavier, egg-laden females could barely manage 4 meters when launched.² These short hops happen mainly during the day, when the insects are actively looking for new feeding trees or mates.

That said, spotted lanternflies are attracted to artificial light. Homeowners in infested areas regularly report the insects swarming around porch lights, streetlamps, and illuminated windows after sunset. This phototactic response is common across many insect groups, and while it does not mean lanternflies are “active” at night in the way a moth might be, it does mean they will occasionally take short flights toward light sources when disturbed or drawn by bright illumination. If you leave your patio lights on during peak season in late summer and early fall, you may find lanternflies landing on your screens and siding. Switching to yellow “bug lights” or simply turning off unnecessary outdoor lighting can reduce this.

How Researchers Track Their Movements

Understanding where lanternflies go, day or night, is complicated by their small size and tendency to blend into bark. Researchers in Pennsylvania and New Jersey have used radio telemetry and harmonic radar to follow individual spotted lanternflies in the field.³ These techniques involve attaching tiny tags to individual insects and then relocating them with specialized receivers. The approach reveals how far the insects move between trees, how long they stay on a single host, and when they are most active.

This kind of tracking has confirmed what casual observers suspect: lanternflies are largely sedentary at night. They do not undertake long nocturnal migrations or disperse into new areas under cover of darkness. Their primary mode of long-distance spread is actually hitchhiking on vehicles, rail cars, and shipped goods rather than flying. The short flights they do take happen overwhelmingly during daylight and warm afternoon temperatures.

Seasonal Shifts in Activity

Where lanternflies go at night also depends heavily on the time of year. Adults do not appear until mid to late summer, typically emerging around late July when enough warmth has accumulated over the growing season. In a two-year study in southeastern Pennsylvania, the first adults showed up on July 23 in one year and July 27 the next, when day length was still around 14 and a half hours.⁴ Peak adult numbers hit around the first week of October, by which point the day had shortened to roughly 11 and a half hours.

This matters because shorter days mean longer nights, and spotted lanternflies spend that extended darkness doing essentially nothing productive. They do not feed, they do not mate, and they do not lay eggs in the dark. As the season progresses and nights grow longer, the insects are simply idle for a greater share of each 24-hour period. This creates a natural bottleneck: adult lanternflies have a compressed window of daylight in which to feed enough to mature their eggs before temperatures drop. The urgency you see in their daytime swarming behavior during September and October is partly a reflection of this shrinking daily window.

Egg-laying itself also tracks day length. In the same Pennsylvania study, the first egg masses appeared in late September, when the day was just under 12 hours long. Females lay their eggs on tree trunks, rocks, outdoor furniture, vehicles, and almost any flat surface, often in sheltered spots where the egg mass will overwinter. This means the surfaces where adults roost at night during early fall may become the same surfaces where egg masses appear a few weeks later.

What Nymphs Do When Disturbed After Dark

Before becoming winged adults, spotted lanternflies pass through four nymph stages. These younger insects cannot fly, which limits their nighttime options even more than adult lanternflies. They stay on whichever plant they are feeding on and rely on their legs to escape threats. A study of over 1,400 nymphs documented three main anti-predator responses: hiding (the most common at about 44% of observations), sidestepping around the stem to stay out of sight (about 32%), and jumping (about 25%).⁵

The hiding response was dramatically more likely when nymphs were on stems compared to leaves. Younger nymphs in particular were far more prone to freezing in place on stems, which makes sense: a small black-and-white first-instar nymph pressed flat against bark is genuinely hard to spot. Older nymphs, especially the distinctive red-and-black fourth instars, were more likely to jump or sidestep, probably because their larger size makes hiding less effective. At night, when visual predators like birds are largely inactive, the strategy of pressing flat against a trunk and staying motionless is especially effective. Nymphs essentially become part of the bark until morning.

Where They End Up When the Season Ends

Adult spotted lanternflies do not survive the winter. They are killed by the first hard frosts, usually by late November in the mid-Atlantic region. So the answer to “where do they go at night” eventually becomes “nowhere,” because the adults die. But the species persists through egg masses, which are laid on surfaces during the fall and overwinter in place.

These egg masses are surprisingly cold-hardy. Research using field-collected egg masses from Pennsylvania found that the eggs are chill susceptible, meaning they die if ice actually forms inside their bodies, but their supercooling points (the temperature at which they freeze) range from about −17°C to nearly −28°C. That is roughly 0°F to −18°F. Eggs survived short exposures to temperatures below −20°C and even some longer exposures at −15°C, with successful hatching afterward.⁶ The researchers concluded that spotted lanternflies may be able to establish in colder climates than originally predicted, with a lower lethal temperature estimated around −28°C.

This has direct practical implications. If you find and scrape egg masses off trees, fences, and outdoor equipment during the winter months, you are eliminating next year’s population before it starts. Egg masses look like smears of dried mud, roughly an inch long, often laid in sheltered crevices on tree trunks. Checking the same trunk sections where adults congregated at night during the fall is a reasonable strategy for finding egg masses in winter.

Practical Timing for Control

Knowing that spotted lanternflies cluster on tree trunks at night and are largely immobile gives you a window for population management. Sticky bands or circle traps wrapped around tree trunks catch adults and late-stage nymphs as they move up and down the trunk during the day. But the nighttime clustering also means that a targeted insecticide application to trunk surfaces in the evening or early morning, when the insects are concentrated and not dispersing, can be more effective than spraying broadly during the day when they are scattered across branches and leaves.

The trunk-roosting behavior also makes visual surveys easier after dark. If you want to know how bad your lanternfly problem is, a flashlight inspection of your tree trunks on a warm September evening will give you a better count than trying to spot individuals fluttering around the canopy during the day. You are likely to find them in tight groups, sometimes dozens deep, particularly on tree of heaven, black walnut, silver maple, and grapevines.¹

If you are in an area where spotted lanternflies have recently appeared, reporting sightings to your state’s department of agriculture matters for tracking the invasion front. An evening trunk check is one of the most reliable ways to confirm their presence, since during the day they can be surprisingly easy to overlook when they are spread across the upper canopy. At night, they come to you.

Why They Favor Certain Trees Over Others

The trees where lanternflies roost at night are not random. Tree of heaven (Ailanthus altissima), an invasive species from China just like the lanternfly itself, is overwhelmingly their preferred host. Adults feed on it, mate on it, and lay egg masses on it. If you have a tree of heaven in your yard and spotted lanternflies are in your area, you can be nearly certain that is where they will be at night. Removing tree of heaven from your property is one of the most effective long-term steps you can take, though it should be done carefully since the tree resprouts aggressively from cut stumps unless treated with herbicide.

That said, spotted lanternflies are generalists. They feed on over 70 plant species, including grapevines, hops, stone fruits, maples, willows, and oaks. When tree of heaven is not available, they will roost on whatever large-trunked tree is nearby. Grapevine growers have been particularly hard hit because lanternflies feed heavily on grape phloem, weakening vines and reducing fruit quality. In vineyards, the insects may roost on trellis posts and vine trunks at night rather than on a separate tree, which means they never really leave the crop.

The relationship between lanternflies and tree of heaven goes beyond simple preference. The tree produces compounds called quassinoids that the lanternflies sequester in their bodies, which may make them distasteful to some predators. This chemical defense is another reason the insects cluster on tree of heaven trunks, especially at night when they are vulnerable and immobile. Researchers studying the short-hop flights of adult females hypothesized that these flights are primarily about finding new host trees on which to feed and complete egg maturation, not about escaping threats.² At night, that search is paused, and the insects stay put on whatever tree they last visited.

The Honeydew Problem After Dark

Even when spotted lanternflies are not actively feeding at night, the evidence of their daytime feeding is everywhere. They excrete large quantities of honeydew, a sticky, sugar-rich waste product that drips from their feeding sites onto whatever is below: cars, patio furniture, sidewalks, and lower foliage. This honeydew promotes the growth of sooty mold, a black fungal coating that is unsightly and can block sunlight from reaching leaves below the infestation.

If you park your car under a tree where lanternflies are roosting and find it coated in sticky residue by morning, the honeydew was deposited during the previous day’s feeding frenzy. The insects themselves are not producing it at night in any significant amount, since they are not feeding. But the accumulation from daytime feeding can be dramatic, and the mold growth that follows is a secondary problem that persists well after the insects themselves have settled down for the night. Moving vehicles, outdoor dining areas, and play equipment out from under heavily infested trees is the simplest countermeasure during peak season.

Honeydew also plays a role in lanternfly social behavior. Research has shown that volatiles from male honeydew excretions attract other males, creating a chemical signaling system that may help explain why the insects aggregate so densely on particular trees. This chemical trail persists on trunk surfaces overnight, so when dawn arrives, the insects are essentially surrounded by signals that reinforce their tendency to stay grouped on the same tree rather than dispersing.