Category Archives: Spotted Lanternflies

Tiny Spotted Lanternflies Are Hatching

First stage nymphs of spotted lanternfly on grapevine, Pittsburgh, 29 May 2023 (photo by Christopher Bailey via Wikimedia Commons)

6 June 2024

When we think of spotted lanternflies we remember the flying adults that plague us from July through early autumn. But these annoying insects don’t start out in flying form.

In May-June their eggs hatch into tiny black nymphs, 1/4″ long, with white spots. If the nymph manages to pass through four instars it becomes a winged adult.

Black nymph spotted lanternfly at Phipps on 4 June 2023 (photo by Kate St. John)

On Monday 3 June, Bob Donnan saw a couple of the black-spotted early nymphs in Washington County, PA. Oh no! They’re already here. The tiny nymphs are hatching.

Smashing them doesn’t work. As Bob remarked, “They jump fast!”

Check out last year’s article on alternatives for trapping spotted lanternflies.

If fewer nymphs make it to the next stage we’ll have fewer annoying winged adults.

Proof! Lanternflies Don’t Hurt PA Trees; Sticky Tape is Pointless, Bad

Sticky tape put on trees by an unknown Frick Park visitor, 19 Sept 2023 (photo by Michelle Kienholz)

20 September 2023

Six years ago, when spotted lanternflies (Lycorma delicatula) were a new plague in North America, no one knew if they would destroy Pennsylvania’s forests but scientists assumed the worst and warned accordingly. However, they also conducted long term studies of spotted lanternflies’ effect on Pennsylvania trees and agriculture. For PA trees there is happy news: Spotted lanternflies are not a danger to Pennsylvania forests. There’s no need to protect our trees from lanternflies because they are not hurting them.

Penn State subjected four species of trees to four years of spotted lanternfly super-infestation by surrounding the trees with mesh nets that kept hordes of lanternflies inside. Silver maple, weeping willow, and river birch were barely phased by the bugs and did quite well in the third year of the study. The bugs’ host plant, the invasive tree of heaven (Ailanthus altissima), did not grow during the plague.

A Penn State study had four types of trees in enclosures with spotted lanternflies inside to see how growth would be affected. credit: Kelli Hoover/WPSU (photo embedded from WPSU)

The study’s lead author, Kelli Hoover, concluded:

“If you have a vineyard and you have lanternflies on your grape vines, you should be very worried because they can kill grape vines,” Hoover said. “But if you’re a homeowner and you have large trees on your property and you have lanternflies on them, I don’t think you should worry about it.”

WPSU: Spotted lanternflies not a danger to forests, according to Penn State study

When scientists learn new information, even if it contradicts an earlier statement, they change their advice to match the reality.

Six years ago they thought the trees were in trouble and needed protection. Now they’ve proven that spotted lanternflies don’t hurt our trees.

Six years ago they suggested sticky tape to protect trees but quickly learned it’s a terrible idea because it kills beneficial insects and birds and immediately changed their advice: Do NOT use Sticky Tape; use Circle Traps instead.

Yesterday an unknown visitor to Frick Park put sticky tape on some trees. Here’s what one section killed: 12 spotted lanternflies, 25+ pollinators (yellowjackets), 70 warbler-food insects (tiny flying insects). More beneficial insects died than lanternflies. Needless to say the tape has already been removed. (Click here to see how sticky tape kills birds!)

Sticky tape deaths in Frick Park, 19 Sep 2023 (photo by Michelle Kienholz)

Sticky tape is bad and pointless. If you put it up, remove it.

Sticky tape on a red oak (photo by Kate St. John)

Learn more about the spotted lanternfly tree study at WPSU: Spotted lanternflies not a danger to forests, according to Penn State study

p.s. Are you still worried because you saw one or two bugs on a tree? Not a problem. In September spotted lanternflies climb any vertical object whether or not they intend to eat it: trees, utility poles, buildings. Here they are on the guy wire of a utility pole. Yes, they are creepy but they are not eating the utility pole.

video embedded from ViralHog on YouTube

(photos by Michelle Kienholz, Kate St. John and embedded from WPSU website)

Honeydew Falls Like Rain

Sooty and white mold grow on honeydew deposited by spotted lanternflies feeding on Ailanthus, Schenley Park, 15 Sep 2023 (photo by Kate St. John)

17 September 2023

The onslaught of invasive spotted lanternflies (Lycorma delicatula) continues in Pittsburgh until the first truly cold weather gives us a couple of frosts. This month the bugs are congregating on vertical objects, feeding on Tree of Heaven (Ailanthus altissima), and laying eggs.

On Friday in Schenley Park the sun broke sideways through the trees to a large Ailanthus along the Lower Trail coated in lanternflies, sooty mold, and white mold (highlighted in yellow). The lanternflies were actively sucking on the tree’s sap.

White mold on Ailanthus beneath the spotted lanternfly feeding zone, Schenley Park, 15 Sep 2023 (photo by Kate St. John)

Sunlight illuminated small bugs flying horizontally near the tree and something falling that looked like rain.

Spotted lanternfly honeydew drops like rain, Schenley Park, 15 Sep 2023 (photo by Kate St. John)

Uh oh! That rain is watery spotted lanternfly poop called “honeydew.” The honeydew is sugary and the air actually smelled sweet.

So stand back when you see a tree coated in sooty mold and spotted lanternflies. You won’t want to get rained on.

Here’s more about sooty mold.

p.s. Don’t worry about honeydew dropping from buildings and utility poles. The lanternflies aren’t eating there so they aren’t pooping either.

(photos and video by Kate St. John)

Spotted Lanternflies Love Height and Heat

Dead spotted lanternfly at the base of a utility pole, 13 Sept 2023 (photo by Kate St. John)

13 September 2023

They aren’t very smart but they know what they like: warmth and vertical objects.

If you haven’t been to Downtown or Oakland lately you’re missing an insect phenomenon. Our plague of spotted lanternflies (Lycorma delicatula) is quite attracted to tall buildings and utility poles, especially when it’s hot.

Spotted lanternflies love this utility pole when the sun heats it (photo by Kate St. John)

Like moths to a flame, spotted lanternflies are visually drawn toward and seemingly captivated by vertical objects such as utility poles …

[They] turn and land on the poles when they are less than about 10 feet away. They remain on the pole for many minutes, even hours, while crawling up toward the top to try to take flight again.

However, a large proportion of those launching themselves from the pole are drawn back to the pole, which serves as a sort of “visual magnet” from which the insects cannot escape for a while. 

Science Daily: Lanternfly’s attraction to vertical silhouettes could help monitor, trap it, April 2021

On hot days I see thousands above me, puttering toward the buildings, tapping along the structures as they try to find a place to land.

This building is especially attractive to spotted lanternflies, Sept 2023 (photo by Kate St. John)

The bugs cling and fall off, leaving drifts of lanternfly carcasses on the ground below.

Spotted lanternflies litter the base of the Rand Building, 11 Sept 2023 (photo by Kate St. John)

There’s a theory that the bugs like vertical objects because they are such weak fliers that they have to climb up and relaunch on their search for their host tree, the Tree of Heaven (Ailanthus altissima). According to Penn State Extension, they “land on buildings for warmth, height and other unknown reasons.” Other unknown reasons: Who can know the mind of a lanternfly?

Fortunately we can learn from Philadelphia where their spotted lanternfly plague hit in 2020 (during the pandemic). Here’s what happened at a taco shop on the ground floor of a high rise.

video from NBC10, Philadelphia, Sept 2020


Note that Philadelphia had their lanternfly plague in 2020 and now, three years later, they are wondering where all the bugs have gone. I’m sure we can expect 2-3 summers of this nonsense. Certainly by 2026 spotted lanternflies will just be a bad memory in Pittsburgh.

(credits are in the captions)

Why Leaves Turn Black Under Tree of Heaven

Spotted lanternfly honeydew below ailanthus tree turns black with sooty mold, Schenley, 25 Aug 2023 (photo by Kate St. John)

27 August 2023

In Schenley Park’s Panther Hollow there are only a handful of Ailanthus altissima trees (Tree of Heaven) which I rarely paid attention to until recently. A couple of weeks ago I noticed that the plants and ground beneath those trees were wet, though it had not rained. This week the leaves and ground are black. Both phenomena are a by-product of the spotted lanternfly (Lycorma delicatula) invasion.

Spotted lanternflies on a tree trunk, one egg mass below them (photo by Emelie Swackhamer, Penn State University,

Spotted lanternflies (Lycorma delicatula) are sucking insects that pierce the bark of their host plant, Ailanthus, and sip the sugary phloem that travels from the leaves to the rest of the plant. (Phloem flow is orange in the diagram below.)

Flow of xylem and phloem in plants (image from Wikimedia Commons)

Everything that eats excretes and spotted lanternflies are no exception. Their watery “poop” is called honeydew because it is full of sugar.

video embedded from Bug of the Week on Youtube

If there were only a few lanternflies we would never notice the honeydew but when a large number coat a tree the honeydew is hard to miss, especially for the consumers of honeydew: bees, wasps, hornets, ants and butterflies.

Butterfly sips on spotted lanternfly honeydew (photo by Rebekah D. Wallace, University of Georgia,
European hornet sips lanternfly honeydew (photo by Rebekah D. Wallace, University of Georgia,

Sugary honeydew eventually grows sooty mold. Everything with honeydew on it turns black.

Sooty mold is a fungus that appears as a black, sooty growth on leaves, branches and, sometimes, fruits. It is non-parasitic and not particularly harmful to plants apart from being unsightly. Potentially, it could affect the plant’s ability to use the sun for photosynthesis. If you can rub the black growth off with your fingers, it is probably sooty mold. If you cannot rub it off, it is most likely something else.

Univ of Hawaii Master Gardener Program: FAQ, Sooty mold
Sooty mold on vegetation beneath Ailanthus tree (photo by Richard Gardner,, yellow circle added
Spotted lanternfly honeydew below ailanthus tree turned black with sooty mold, Schenley, 25 Aug 2023 (photo by Kate St. John)

Eventually white mold may cover the honeydew. I haven’t seen this yet but I’m watching for it.

Spotted lanternfly honeydew grows mold (photo by Lawrence Barringer, Pennsylvania Department of Agriculture,

Will we ever be free of spotted lanternflies? Yes! Check out this blog This, Too, Shall Pass.

(photo credits are in the captions with links to the originals)

This, Too, Shall Pass

Spotted lanternflies land to roost just before sunset, Pittsburgh, 22 August 2023 (photo by Kate St. John)

24 August 2023

Spotted lanternflies (Lycorma delicatula) are everywhere in the East End of Pittsburgh and along our rivers and railroads. One even triggered a snapshot on the motion detection camera at the Pitt peregrine nest. Aaarrg!

Spotted lanternfly perched on the National Aviary snapshot falconcam at Univ of Pittsburgh

Right now, while the invasion is getting worse by the day, it is hard to imagine a time without them but that day will come. The bugs have daily, seasonal and annual cycles and their population trend goes down, based on what happened in eastern PA where they were first detected. Let’s take a look.

Daily dispersal, nightly roost. During the day adult lanternflies disperse to the sky but at dusk they land on buildings and trees to “roost” overnight. Dusk is an unpleasant time of day as they aggregate near us but it’s a good opportunity to catch them with a water bottle (video shows how). [Put a lid on the bottle and the bottle in the freezer. They die in the cold.]

Seasonal disappearance of adults in late fall. Spotted lanternfly adults mate and lay eggs in late summer and fall. Winged adults started to appear in July in Pittsburgh but they did not reach a crescendo until mid-August. They’ll be present in September and October and completely die off at the first frost. I expect their presence to taper before they disappear.

I have not been able to find out if the individuals die shortly after mating and laying eggs but if so the population would taper quickly. I’ll know more in November.

Invasion lasts two to three years based on experience in Eastern PA.

Lanternflies were a plague in Berks County(*) in 2018 and 2019 but by 2021 they were hard to find. That year the Reading Eagle wrote “Where have all the spotted lanternflies gone?

Similarly the bugs plagued Philadelphia in 2020 but reports went down 95% in 2022 and this month the Philadelphia Inquirer asks Should we still care about spotted lanternflies in 2023? and What should you do if you see spotted lanternflies?

Notice that Philadelphia is saying “IF you see spotted lanternflies,” not “WHEN you see spotted lanternflies!”

Based on these reports I’d say the infestation lasts two to three years and then drops to an unremarkable level. It seems to be a bell curve.

Spotted lanternfly invasion appears to be a bell curve with maximum at 2-3 years (guesstimate by Kate St. John)

The Pittsburgh area has had spotted lanternflies since 2020. This summer we are in the first plague year (Year label 5). Next summer will be bad, too, but by 2025 or 2026 they’ll be virtually gone.

This, too, shall pass.

p.s. Great News! Two naturally occurring native fungi infect and kill spotted lanternflies in great numbers. Batkoa major and Beauveria bassiana decimated the spotted lanternfly (Lycorma delicatula) populations near Reading, Pennsylvania in 2019. Fingers crossed!

(*) Berks County in 2014 is the location where spotted lanternflies were first identified in the U.S.

(photo by Kate St. John and from the National Aviary snapshot camera at Univ. of Pittsburgh, graph by Kate St. John)

Never Use Sticky Tape for Lanternflies! It Kills Birds!

embedded photo from Audubon News: Downy Woodpecker found in Brooklyn. Photo: Sarah Valeri

22 August 2023

Invasive spotted lanternflies are swarming over Pittsburgh right now, especially near the railroad tracks. Everyone wants to kill them but the first solution that comes up on any Google search is a very, very bad one. NEVER EVER use sticky tape to capture insects. Glue tape kills birds!

Audubon News, the source of the embedded photo above, wrote about the hazards of glue tape last March: Meant to Catch Spotted Lanternflies, Glue Traps Are a Horrifying Hazard for Birds. Only 10% of the trapped birds survive, even if they’re taken to a rehabber.

Raven Ridge Wildlife Center in Lancaster County, PA has years of experience with the harm caused by glue tape. This Facebook report from 17 August 2023 is just one of them. Three of the four trapped woodpeckers died and the fourth is in trouble.

So what can you do to kill lanternflies?

For trees use the Circle Trap. You can make it yourself. Instructions found here.

For home, make a simple vinegar trap :

Spotted lanternfly and insect vinegar trap (photo by John English)

Straight white vinegar plus dish liquid — maybe a 1/2 tsp — to break the surface tension. (Insect by-catch in this photo: a cicada.) Thanks to John English for this suggestion.

For personal combat there are lots of solutions: Electric “Tennis Racket” bug zappers, the Bug a Salt Gun, etc. found via Amazon searches.

Electric “tennis racket” bug zappers via Amazon search
The Bug a Salt gun via Amazon search

Watch a champion spotted lanternfly killer use these tools in a video from VICENews:

video from VICENews on YouTube

p.s. Why are spotted lanternflies more prevalent near railroad tracks? They arrived as egg masses stuck to railcars and hatched from there. Their host tree is the Ailanthus, an invasive weed that grows along the rail lines. They were first found in southwestern PA at a rail yard in Beaver County in 2020.

(photo and video credits are in the captions)

The Bugs Are Busy

Butterfly weed, Schenley, 9 August 2023 (photo by Kate St. John)

13 August 2023

The birds are quiet now but the bugs are busy.

After I photographed this butterfly weed (Asclepias tuberosa) I zoomed in to look at the yellow spec on the back edge of the flower cluster and found a tiny yellow crab spider clinging to the flowers. My guess is that he’s a member of the Thomisidae family, lying in wait for something. But what?

Tiny yellow crab spider on butterfly weed, Schenley, 9 August 2023 (photo by Kate St. John)

On Monday, while walking the Three Rivers Heritage Trail River opposite Herr’s Island, I noticed a caterpillar on the wide aluminum railing. It reminded me of the hickory tussock moth except that this one was blonde.

Sycamore tussock moth caterpillar near Herr’s Island, 7 Aug 2023 (photo by Kate St. John)

iNaturalist identified it as a sycamore tussock moth (Halysidota harrisii). The railing was directly beneath his host plant, a sycamore tree (Platanus occidentalis).

Sycamore leaves and stems, Aug 2023 (photo by Kate St. John)

The caterpillar walked rapidly down the railing in a straight line until Whoa! a spotted lanternfly red nymph walked rapidly toward him. The caterpillar made a detour.

Sycamore tussock moth detours to avoid a spotted lanternfly, 7 Aug 2023 (photo by Kate St. John)

At Frick Park on 6 August we found a lot of millipedes on the paved Nine Mile Run Trail. iNaturalist says they are greenhouse millipedes (Oxidus gracilis), thought to be native to Japan but introduced around the world. They get their name from being a pest in greenhouses.

Greenhouse millipede, Frick Park, 6 Aug 2023 (photo by Kate St. John)

And finally I was fooled yesterday by these mating orange and black bugs, as fooled as they intended me to be. They looked like milkweed bugs, but why were they on a false sunflower?

False milkweed bugs mating on a false sunflower, 11 Aug 2023 (photo by Kate St. John)

I should have known! These are false milkweed bugs (Lygaeus turcicus) who masquerade as a poisonous species and whose host plant is the false sunflower. Read more about them and the bugs they imitate here.

(photos by Kate St. John)

What Kills Spotted Lanterflies?

Damaged adult spotted lanternfly, Pittsburgh, 22 July 2023 (photo by Kate St. John)

8 August 2023

Aaarrg! They’re everywhere! Pittsburgh is in the midst of a spotted lanternfly (Lycorma delicatula) invasion and it’s just plain creepy. These bugs don’t bite but they’re large, they leap and fly unpredictably, and there are just so many of them. Even when damaged like the one above, they’re disgusting. Make them go away!

So what kills them? I’ve seen a few birds attempting to catch the nymphs but those few birds can hardly make a dent in such an overwhelming insect population.

For now it’s up to humans kill them. Not with poison but by more ingenious means.

How about robots? Carnegie-Mellon’s Robotics Institute developed a robot that scrubs spotted lanternfly (SLF) egg masses off trees in winter so they can’t hatch the following spring. This is fascinating and useful in the long run for orchards but it doesn’t help us today. (1:29 minute video)

video from Global Update on YouTube

Another long term solution is to introduce SLF’s natural predators. Researchers in Delaware are studying two species of parasitic wasps from China that target spotted lanternflies but it will take years to make sure these tiny wasps are totally dedicated to SLF and will not attack North American species. If these wasps pass the test they’ll provide a long term solution for vineyards. (3:00 minute video)

video from CBS Philadelphia on YouTube

And then there’s just plain killing them. The second half of this 2022 video shows how a woman in Gillette, NJ kills them in bulk. Favorite tool? An electric “tennis” racket! (Entire video here is 8 mins long. Excerpt is 4:00 minutes)

video from VICENews on YouTube

If you live in southwestern PA and haven’t seen a lot of lanternflies yet, just wait. Butler, Lawrence, Fayette and Somerset Counties were added to the SLF quarantine this year. Forewarned is forearmed … with an electric “tennis” racket!

Spotted lanternfly quarantine counties in Pennsylvania as of 25 Feb 2023 (map from PA Dept of Agriculture via Penn State Extension)

Check out local answers you can use right now in this 1-hour-long Lunch and Learn about Spotted Lanternflies presented by Phipps Conservatory.

(photo by Kate St. John, map from PA Dept of Ag via Penn State Extension, video credits in the captions)

Literally Outside My Window

Sunrise with mammatus clouds, Pittsburgh, 29 July 2023 (photo by Kate St. John)

5 August 2023

Some amazing things were quite literally outside my window last week.

Above, nearby thunderstorms at sunrise on 29 July produced these ominous mammatus clouds.

Two days later a complete rainbow with purple arcs filled the sky. The purple is too faint to see in this photo.

Rainbow in Pittsburgh, 31 July 2023 (photo by Kate St. John)

It was also a week of large flying insects.

Larger elm leaf beetles (Monocesta coryli) have been flying by 60 feet above the pavement. This one rested on my window.

Larger elm leaf beetle, 29 July 2023 (photo by Kate St. John)

And spotted lanternfly adults (Lycorma delicatula) fly higher than you’d think. Their numbers increased dramatically in the past week.

Spotted lanternfly outside my window, 2 August 2023 (photo by Kate St. John)

No one’s talking about wildfire smoke but something was causing Code Orange air on Thursday. Air quality improved long before sunset.

Sunset, 3 August 2023 (photo by Kate St. John)

(photos by Kate St. John)