Blog | Tree Care
Walk out to the car on a warm September morning in Fairfax and you will probably find one on the door — an inch long, grey forewings with black dots, red underwings that flash when it jumps. Then you notice a dozen more on the maple by the driveway, a sticky film on the patio table underneath, and a black sooty crust forming on the pavers.
The phone calls we get at that point all ask the same thing in different words: is this insect killing my tree, and what do I spray?
The honest answer is less alarming than the sight of them, and it points somewhere most homeowners do not expect.
For the great majority of shade and ornamental trees in a Fairfax yard, they don’t. That is not a tree company softening bad news — it is the position of Fairfax County’s own Urban and Community Forestry Division, which states plainly on its spotted lanternfly page that the insect “will not harm most trees and yard plants,” and that lanternflies “have not been the primary cause of death to ornamental and shade trees.”
What they can be is a stress multiplier. Nymphs and adults have piercing, sucking mouthparts that draw sap from stems and twigs, and in heavy numbers the County notes they become “a contributing stress factor by reducing a tree’s ability to synthesize and store energy.” Feeding at that scale can cause oozing sap, leaf curl, and twig dieback.
The trap is that a swarm is extremely visible and the real causes of decline mostly are not. A tree with three hundred lanternflies on the trunk looks like it is being eaten alive. The County’s own framing is worth sitting with: other environmental factors, especially too little or too much water, have a far greater impact on tree health than the insects crawling up the bark.
There is a short list, and it is worth knowing because it is much narrower than the panic suggests. Lanternflies are only known to kill young saplings, grapevines, and tree-of-heaven itself. They show a strong preference for fruit trees, maples, black walnut, birch, and willow — but feeding on those species is not, on its own, a death sentence for an established tree.
So the calculus for a fifty-year-old red maple over a Fairfax driveway is different from the calculus for a whip you planted last spring, or for the grapes on an arbor out back. Young, thin-barked, small-reserve plants have no margin. A mature tree has a great deal of it.
The County’s guidance opens with an instruction that is easy to skip past: take a breath, and do not aim for eradication, because eradication is not achievable. Manage the area instead.
In practice, on a residential lot, that means a handful of low-tech things:
Timing matters for the second item, and this is the month it starts. According to Virginia Cooperative Extension’s life-cycle publication (ENTO-268NP, last reviewed August 2025), eggs hatch in early May, nymphs run until late July when they become adults, and adults begin laying eggs in September. The grey, mud-smear-looking masses going up right now on trunks, fence rails, grill covers, and the underside of anything flat will sit there all winter. Late fall through early spring is the easiest window of the whole year to reduce next season’s population on your own property.
Ask where the swarm came from and the answer, more often than not, is a tree-of-heaven (Ailanthus altissima) growing along a fence line, a drainage easement, or the scrubby edge behind a Fairfax cul-de-sac. It is the lanternfly’s preferred host and its native companion from East Asia. The County is blunt about the sequence: lanternflies typically find tree-of-heaven first, then spread out to everything else nearby. Fairfax County has been removing it from County-owned property specifically to slow that spread.
Taking one out of a yard does not create a lanternfly-free bubble, but it does remove the magnet — and that matters most when the tree is anywhere near a patio, deck, playset, or parked car, where honeydew rains down and sooty mold follows.
Here is the part homeowners routinely get wrong: you cannot simply cut it down. A cut stem is a trigger. The roots respond by throwing sprouts, and each of those has to be cut again, and again, until the root system finally exhausts itself. Real control means taking out the root system or treating it, which is why tree-of-heaven belongs with professional removal and follow-through on the stump rather than a Saturday with a chainsaw. Where the stump has to come out below grade so nothing resprouts through a lawn or bed, grinding it out is the step that closes the loop.
Sometimes, rarely, and not as a first move. Fairfax County frames chemical control as a last resort, to be used only where it is safe for people, pets, and pollinators, and only after asking whether smashing, vacuuming, or trapping would do the job.
Two facts take most of the appeal out of a spray program. There is no preemptive pesticide that keeps lanternflies off your property — they are strong jumpers and gliders that move freely between yards, so a treated tree is simply a tree they can land on again tomorrow. And there is currently no long-term treatment, meaning persistent infestations would likely need treating annually, indefinitely.
One more piece of County advice deserves repeating in a season when lanternflies are in the news: be wary of anyone going door to door offering a bargain treatment. A pitch that arrives on your porch, unprompted, with a number that sounds too good, usually is.
Strip away the spectacle and the question becomes the ordinary one: how much reserve does this tree have? A healthy tree can absorb a season of lanternfly feeding the way it absorbs a dry August. A tree already carrying compacted soil over its roots from a patio job, a trunk wound from a mower, girdling roots, or years of too little water has no slack — and lanternflies land on the same tree the neighbors are pointing at.
That is the case where it is worth having someone look, because the thing to diagnose is not the insect. A tree health assessment answers whether the canopy thinning you are seeing is lanternfly feeding, drought carry-over, root damage, or decay that has been building quietly for years — and whether the tree is sound enough to leave standing over a driveway. That distinction is the whole ballgame, and you cannot make it from the ground with the naked eye.
Should I kill spotted lanternflies when I see them?
Yes — crush or vacuum what you can safely reach, and destroy egg masses. Just understand the goal is keeping numbers down on your property, not wiping the insect out regionally.
Do they bite or sting? Are they dangerous to pets?
No. Fairfax County states they do not sting, bite, or cause harm to pets — though a dog or cat that eats enough of them may vomit.
What is the sticky film on my patio furniture?
Honeydew: undigested plant sugars the insects excrete, which drop onto whatever sits below. It is harmless to people but attracts ants, flies, bees, and wasps, and black sooty mold grows on it, staining surfaces and shading the plants underneath.
Do I still need to report sightings in Fairfax County?
No. Spotted lanternfly was found in western Fairfax County in 2022 and is now found throughout the county, and the County has said reports are no longer needed.
How long does it take spotted lanternflies to kill a tree?
For most established shade and ornamental trees, they do not. Fairfax County’s urban foresters state that lanternflies will not harm most trees and yard plants and have not been the primary cause of death to ornamental and shade trees. They are only known to kill young saplings, grapevines, and tree-of-heaven, though heavy feeding can act as a contributing stress factor on a tree that is already struggling.
If a tree in your yard is thinning, dropping limbs, or leaning over something you care about, the lanternflies on the trunk are probably the least interesting thing about it. We work across Fairfax and the surrounding Northern Virginia communities, and a great deal of what we do on residential properties is sorting the alarming-looking from the actually urgent.
G & V Tree Service Inc
6434 Brandon Ave Suite 204
Springfield, VA 22150
(703) 569-2570
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