Spotted Lanternfly in Princeton

Most people by now have heard of the spotted lanternfly, an insect native to China, Vietnam and parts of India that somehow showed up in eastern Pennsylvania in 2014. A leaf hopper with distinctive markings and colorful wings, it spread rapidly as it sucked the juices out of grape vines, orchards, and trees like Ailanthus, black walnut, maple and red oak.

Two years ago, local papers reported a sighting of spotted lanternfly in northeastern Princeton. Last year, the summer of 2019, a couple friends reported seeing it in Princeton--Mimi found a few in her backyard in western Princeton; Scott saw some in Herrontown Woods near the parking lot. 

For me, it didn't become real until I encountered this curiously tilted nymph on a butternut tree leaf near Veblen House in Herrontown Woods in early July. A Penn State Extension post describes the insect's colorful development from egg to nymph to the winged adults that emerge in late July.

For some reason, I had avoided writing about the spotted lanternfly. Maybe I was maxed out on the world's problems, and didn't really want to delve into the prospect of yet another introduced insect wreaking environmental havoc. 

Unlike the Emerald ash borer, which has gone largely unseen as it skeletonizes our vistas, quietly killing every untreated ash tree in Princeton, 

the spotted lanternfly sounded poised to make a highly visible and messy invasion. The PA Dept. of Agriculture published a pdf with graphic photos showing mildewed foliage and tree trunks covered with the adult insects. And because plant juice is very dilute, the sucking insects need to move a lot of juice through their bodies to get the nutrition they need. That means that both nymphs and adults expel large amounts of "honeydew", which drops down from the trees and vines, and coats foliage on the ground with sugary liquid, promoting the growth of mold. Their egg cases look like mud, affixed to trees or cars or most anything. It sounded like our habitat restorations and garden beautifications would be reduced to a tattered, moldy mess.

Below are compiled some research and experiences with spotted lanternfly this past weekend at Herrontown Woods. 

Ailanthus--the Spotted Lanternfly's favorite food

Turns out that the spotted lanternfly has a strong preference for sucking the juices of Tree of Heaven (Ailanthus altissima). Native to China, Ailanthus is fairly common in Princeton and can be invasive, forming clones and sprouting aggressively from its roots if cut down. A stand of Ailanthus can be used for trapping the spotted lanternfly. Penn State extension offers tips for homeowners on this. 

At the Herrontown Woods botanical garden, next to the parking lot, we have an Ailanthus growing, and sure enough, some adult lanternflies were found clinging to its bark.

Looking up, the Ailanthus leaves appear to be getting eaten, though the lanternflies are said only to suck from the trunk and the stems, not the thinner tissue of the leaves themselves. 

In a sense, the preference for Ailanthus is good news. An invasive tree is being attacked by a newly introduced insect from a similar region of the world. But the tree is also helping the insect expand its numbers through the summer, and toxic compounds in Ailanthus, when ingested by the lanternfly, may confer some protection from predators.

The lanternfly's honeydew is causing sooty mold to grow on the plants underneath the tree.  The NJ Dept. of Agriculture info sheet reports that the sap dripping from "weeping wounds" on tree trunks can attract stinging insects. 

Probably the best thing to do is to take down the Ailanthus, using techniques described here.

More advice for homeowners

There's an enjoyable and clever article on various tactics on the MercerMe site. For instance, the adults are very quick to jump if you try to squash them. The article says their reflexes slow down with persistent efforts, however. Will test that next time. 

Utilizing more finesse is a trap a Pennsylvania teenager came up with after watching the lanternflies climbing the trunks of trees. She ringed the tree with tin foil to channel the ascending insects into a bag, where they would die within 24 hours. Another thorough read for homeowners is at this link, including a test to see if chickens would eat them. They didn't,

but something is clearly eating them, as these wings at Herrontown Woods show. 

Longterm prognosis

Will the spotted lanternfly prove to be a longterm calamity, like the Emerald ash borer, or fade into the background as a passing problem? Will it be a lasting plague for vineyards and apple orchards? An article reports that few lanternflies were seen this year in the area of Pennsylvania where it was first discovered five years prior.  Local Princeton arborist Bob Wells is quoted in the Town Topics as saying that though vineyards and apple growers have reason for concern, for homeowners the insect "won't be much of a threat at all." I inquired on a listserve that includes land managers in Pennsylvania who have had the insect around for several years now, and got mixed responses. One observed reduced numbers one year, then a rebound the next. 

It can be hard to know if you have spotted lanternfly in your trees. My friend LisaB, who lives near Herrontown Woods, had a couple black oaks fall near her property in late July, and was surprised to find numerous SLF nymphs on the leaves that until then had been elevated 70 feet above the ground. She had seen none in her yard up to that point. Her photos show the last nymph stage (red), 

  

and a beautifully captured example of what a newly formed adult looks like. Documented in past posts on this blog, insects like cicadas, butterflies, and apparently spotted lanternflies as well, must hang down as they unfurl their new wings. If the wings brush up against any obstruction, they can easily become misshapened. 

Update, Aug. 6: Walking through Quarry Park, closer to downtown, I noticed some Ailanthus trees near Spruce Circle,  looked up at the leaves above, and saw them there as well, a few scattered adults sucking juice from the rachis of the compound leaves. Will the spotted lanternfly be background or foreground, a quiet addition or serious pest? Time will tell. 

In the meantime, it looks like removing Ailanthus trees would be the most straightforward way to limit this new arrival's numbers and impact.

Reporting: I tried reporting the Herrontown Woods and Quarry Park sightings. The email address bounced, and the telephone number is always busy. It may be that the state doesn't want to hear about sightings in counties where the insect is already present, or maybe it's so widespread by now that the information isn't helpful.

Does milkweed kill lanternflies?

On the leaves of common milkweed growing near our Ailanthus tree, I found several lanternflies belly up or immobilized, leading to speculation that the insects sucked juices from the milkweed and died from the toxins therein. Apparently, as an introduced species, they have yet to evolve an aversion to the plant.

Reading the Landscape Along the Towpath -- Early Spring

One place that gets a lot more interesting if you know plants is the towpath along the Delaware and Raritan Canal. For those into reading the landscape, the section just upstream of Harrison Street in Princeton makes for a good read, packed with history, beauty, poignancy, and the drama of invasion. 

First, there's the water, here with branches of elderberry reaching out over the canal in the foreground. Elderberry characteristically sprouts leaves earlier than other native shrubs. Water teaches the richness that reflection can bring to life. 

Along this stretch of towpath, the strip of land between the canal and Carnegie Lake widens, making enough room for a nature trail loop that for nearly 20 years has given hikers and joggers relief from the linearity of the towpath. Part of my life has been dedicated to making interesting destinations along very long trails, whether in Durham, NC or in Princeton. With a hardwired devotion to things, I've been an advocate for this little nature trail, and the unique, savanna-like habitat it winds through, since it was created nearly 20 years ago. Periodically stopping by to check that the trail hasn't been blocked by fallen trees, reading the landscape as I go, I always come away with a mix of joy, gratitude, and grief. 

Some flowers encountered during this walk are native, like this red maple reaching out over the trail.

Then there are some non-native species that fortunately aren't invasive, and speak to past intention. These photos were taken a week ago, when the ornamental cherries were just starting to pop. 

These really old ornamental cherry trees are reminiscent of those planted along the Potomac River in Washington, D.C. long ago. The cherry trees and the yellow spray of forsythia off in the distance show that this seemingly wild stretch of the towpath is actually populated with botanical remnants of another era, back when the university installed these plantings as an ornamental entryway to the campus. 

Adding to the evidence of past caretaking is a derelict row of winter honeysuckle (Lonicera fragrantissima), with very small, very early, and very fragrant flowers. Though it's included on invasive species lists, I've never seen it spread. 

If you're an environmental advocate at a local level, a walk can become a review of past successes and failures. For years, the DR Canal State Park, of which this ribbon of land is a part, would keep this nature loop mowed, but then their maintenance budgets started getting cut. Around the time one of their longtime mowing crew members died, they decided to turn mowing over to the landowners--Princeton University. That handoff happened at an administrative level, but not on the ground. After trying in vain to get the university to take care of the trail loop, I finally contacted Shana Weber at the PU sustainability office. Thankfully, she was able to reach the right people, and the trail is now being kept open. 

But one bit of mowing that the state parks people used to do has yet to be picked up by the university. And here's where the landscape's story shifts from joy and gratitude to grief. The nature trail loop winds through what for many years has been a savanna-like landscape of scattered trees and fields. Scattered trees allow enough sunlight to reach the ground to power a rich understory of wildflowers and shrubs. But due to a lack of annual mowing, that special landscape of forest openings, seldom found elsewhere, is being lost. Here is a forest opening that has become a layer cake of invasive plants, with multiflora rose blanketed by a web of super-aggressive porcelainberry vine. 

Other invasive vines also run rampant, like this Japanese honeysuckle smothering a branch.

Why is no one cutting the oriental bittersweet at the base of this tree, the wild gardener in me asks.

Many of the trees were planted, then ultimately abandoned, leaving a kind of derelict arboretum.

Some trees have succumbed altogether to introduced insects or disease, most commonly Emerald ash borer or bacterial leaf scorch. 

On the ground, the uber-invasive lesser celandine is laying a claim that will surely expand. 

Without annual mowing to sustain the forest openings, a tortured form of succession is underway, with sweetgum saplings being mobbed by the invasive vines. Annual mowing would sustain the special forest openings and reduce the smothering invasives.

A couple places where the native species are doing well are, not surprisingly, in standing water. Here's a rosette of a very healthy rose mallow hibiscus (Hibiscus moscheutos), its feet very much in water.

Here's a shrub that also flourishes in standing water, buttonbush (Cephalanthus occidentalis). 

There are lots of native plants that can thrive in floodplain habitats along the canal. If the university ever gets interested in habitat restoration, this would be a great place to start. It would be a high-visibility demonstration, to be witnessed by all the hikers, bicyclists, and joggers passing by, who currently see not the history and the ecological drama but just another stretch of green.

Optimism, Habitat, and Landscape

If people love trees so much, then how do we explain Jill Biden's choice for a painting that was part of Inauguration Day ceremonies in the Capitol rotunda. Painted by African American artist Robert Duncanson as the Civil War was looming, Landscape With Rainbow depicts a pastoral paradise in which a young couple and their cattle head back to a homestead blessed by a rainbow. 

A closer look reveals that the distant hills in the painting are forested, but it is pasture--albeit a bit overgrazed--that dominates this optimistic landscape. Though people love trees, we also love vistas, which trees are very good at blocking. Who hasn't climbed a mountain, expecting a grand vista at the top, only to find that trees have grown to block the view? 

It seems strange sometimes that communities don't actively seek to create and preserve vistas, given how pleasing they are. If people can see into the distance, maybe they'll think into the distance as well. A vivid memory from the Sourland Mountains, just up the road from Princeton, is a view of the Manhattan skyline. It came as a complete surprise, and was made possible only by the ongoing suppression of trees along the gas pipeline right of way that extends up and over the mountain ridge. Ideally, vistas would be made possible in our world by something less linear and fossil fuel-related than a pipeline, but our approach to managing preserved open spaces seldom offers an alternative means of creating areas that are more open. 

Also running counter to open space preservation norms, the focus of optimism in the painting is a house, embraced by nature, towards which the rainbow, people and animals all point. One approach to purchasing open space for preservation is to demolish any buildings left on a newly preserved property. We had to overcome this bias against buildings embedded in open space in the process of saving Veblen House and Cottage at Herrontown Woods. 

One question, then, is how to adjust the classic view of open space--as uninterrupted forest--to consider the clear attraction we have for the mosaic of habitats depicted in this painting, where people play an active role in the landscape. What is pleasing to people can also serve the needs of biodiversity. At the Botanical Art Garden at Herrontown Woods, we are actively preventing a forest opening from reverting to the deep shade that stifles the growth of so many native plant species less gifted with height. Succession to forest need not be considered the only natural destiny for a landscape. Historically, such forest openings would have been maintained by periodic fire, in what is called a fire-climax community. 

Though a deep forest of towering native trees can evoke a sense of awe and reverence, and deserves to be preserved, many areas of preserved open space are thick with stunted, second-growth trees. Add the typically dense layer of invasive shrubs and the effect becomes cluttered and claustrophobic. As the death of ash trees due to the Emerald Ash Borer opens up the forest canopy, we may want to manage some of these openings to create a more varied habitat. If the non-native invasive shrubs can be limited, and young trees kept from reclaiming the sunlight, there are many native shrubs that could flourish in a more illuminated understory. Spicebush, hazelnut, serviceberry, native azalea, blueberries, Viburnums, Hearts-a-burstin'--these are a few of the native shrubs that would bear abundant fruit for wildlife if given more sun. 

One of the most optimistic moments I had in my life had some parallels to the Duncanson painting. I was driving out of Washington, DC after picking up a passport. The president at the time was highly competent and believed in government, and the WhiteHouse gleamed brilliant white in the afternoon sun as I drove past. On the radio was a live broadcast of Copeland's Appalachian Spring, broadcast from the Library of Congress in honor of its premier performance there some 50 years earlier. Along the roadsides as city began to transition to countryside were prairie grasses, golden in autumn. The youthful roadside vegetation resonated with the music of spring's awakening, and a sense of the nation's promise. 

Grasslands, meadows, shrublands--these are the younger landscapes, whose dynamic growth happens at our own height rather than far above. Their flowers and foliage also serve the insect community through the summer when deep forest has gone floristically silent. The aim here is to become more strategic and discerning about trees, to determine where they are precious, and where they might best be managed to serve ecological and aesthetic goals. 

Nature at the Princeton Battlefield

(Thanks to those who commented. Scroll down for an update.)

As a lover of both nature and history, I experience the Princeton Battlefield differently than most. There's gratitude for its preservation, along with some grieving for the way the land is managed. Nature here is pushed to the fringes, as if to replicate a giant ballfield. But the battle took place on a working farm, not an athletic field. 

The Clark House has been restored, its 18th century charms highly valued. So why would the landscape not be similarly treated? In the winter of 1777, the soldiers would have been treading through corn stubble, or pasture, or an orchard. 

One answer would be that visitors and re-enactors benefit from a clean surface. The question then would be how much to mow and where, so that people could enjoy a lawn, but also have areas that evoke more a feeling of the 18th century. 

As I walk across the field, I feel a sense of space more than place. Perhaps if I tried I could feel grandeur, or solemnity. Graveyards are mowed, after all. A big sky and a big field help us to understand that something big happened here, when a nation was being born, its future stretching far off towards the horizon. Maybe the landscape works in some spiritual way to evoke freedom and possibility. But as I walk these hallowed grounds, I'm also feeling a sense of a long ways to go before reaching anything interesting. Okay. Perhaps that long trudge could generate some appreciation for the long overnight march of Washington's amateur army from Trenton to Princeton. 

One tree stands in the middle of the giant lawn, an offspring of the great Mercer Oak that had witnessed the battle and lived through two more centuries before falling to a windstorm in 2000. Trees growing at the time of a great battle are called witness trees. The soldiers who fought that pivotal battle are long gone, but centuries later a tree, especially the long-lived white oak, could still claim "I was there!"

The offspring was donated by Louise Morse, spouse of Marston Morse, a mathematician who Oswald Veblen helped bring to the nearby Institute for Advanced Study in the 1930s. It was Veblen's initiative to acquire the 600+ acres behind the Battlefield that later became the Institute Woods.

The sign tells the story of the white oak and General Mercer. What I've come to look at, though, is not the highly symbolic tree but a thin sliver of golden brown in the distance. 

Beyond the lawn, towards the back of the Battlefield, is a meadow that is mowed once a year. For some reason they mowed the edge of it this fall but have left the rest, perhaps as winter cover for wildlife.

Taking a closer look, I'm surprised to see that, among the blackberries and prairie grasses, goldenrods and asters, are myriad sassafras sprouts, most of them bright orange this time of year. The meadow is a giant clone of sassafras--one root system with ten thousand heads. Can't say I've ever seen that before. 

To the left of the field is a bedraggled woods, dominated by the skeletons of ash trees killed by the introduced Emerald ash borer. A heroic American tree species silently meets its demise.

Behind the Clark House, and also across Mercer Street to the left of the pillars, more signs of introduced invasive species abound. Rampant invasive porcelainberry is stifling the 1976 bicentennial plantings--flowering dogwoods and daffodils around the edge of the field. As is typical of the landscapes we daily tread, the Princeton Battlefield invests in mowing the grass, while leaving the unmowed areas untended and overrun. Each year the Sierra Club organizes a spirited volunteer day to battle against bamboo near the Clark House. In the past, I would lead a group to cut the aggressive porcelainberry vines off of the bicentennial flowering dogwoods, but it's hard to make lasting progress when unsupported by the state agency that views grounds maintenance of this state park as "mow and go." Now all I do is make annual visits to snuff out a small infestation of mile-a-minute I spotted some years back on the Battlefield grounds.

Surely the soldiers who fought here knew their plants better than most people do today, and would feel disoriented by today's massive lawn surrounded by alien weeds. If I were to envision a battlefield landscape that sought to provide a more historically authentic botanical and horticultural context, I'd imagine some portion of the massive lawn being given over to the sort of landscape the battle was actually fought upon--pasture, orchard, corn field, whatever research shows to have been likely at the time. Along the edges would be native forest rather than tangles of kudzu-like nonnative vines. 

According to its mission statement, the Princeton Battlefield Society seeks to "restore the lands and cultural landscape." Maybe once other admirable goals are achieved, someone in the group will get interested in showing people an authentic 1777 landscape, and get the state parks department to help in the effort.  

To acquire, protect, preserve, and restore

the lands and cultural landscape related

to the Battle of Princeton of 1777;

To enlarge and improve the

Princeton Battlefield State Park;

To educate the public about the Battle

of Princeton, the Ten Crucial Days,

and the American Revolution.

Update, Dec. 23, 2022 : It's not hard to find accounts of the chronic underfunding of maintenance for NJ's state park system. This cuts both ways for Princeton Battlefield State Park. It explains why invasive species run rampant along the fringes of the park, but doesn't explain the large investment in mowing. One could have a mowed area around the house and for the areas of the land used for re-enactments and other events, and for visitors to explore the park (we used to fly kites there). Surely that still leaves large areas that could be managed for meadow. 

Nearby the Institute for Advanced Study grounds provide an example of large areas requiring only an annual mowing. 

Ribbons of mowed grass through meadow at the Battlefield would not only reduce mowing but also invite visitors to explore the full extent of the park. Walking across a vast lawn gives little sense of progress, departure, or arrival, and thus doesn't encourage exploration the way a mowed path does. 

The current management, in which nature is either suppressed by mowing or neglected along the fringes, does not reflect the view of nature held by the battle's greatest hero. George Washington was, among many things, a farmer. He believed plants were so important to a nation's future that he "had a dream of a national botanic garden and was instrumental in establishing one on the National Mall in 1820." 

In our era, when most people suffer from plant blindness, it must seem incongruous that the United States Botanic Garden is located immediately adjacent to the U.S. Capitol building. Plant blindness, according to the botanists who coined the term, "results in a chronic inability to recognize the importance of plants in the biosphere and in human affairs."

With this in mind, some rethinking of how vegetation is managed at the Princeton Battlefield could add to the visitor's experience, and shift some funds from mindless mowing to a mindful restoration of a more historically authentic landscape.

Three Ways a House Can Feed a Raingarden

(First, a note: The Historical Society of Princeton is hosting Community Days the first Saturday of every month out at its Updike Farmstead on Quaker Road. More info at this link.)

Last month, the Updike Farmstead Community Day featured yours truly. I had planned to give three different presentation, but since most people came to hear about Herrontown Woods and the Veblen legacy, I ended up giving that presentation twice.

We did get outside long enough to check out the trees and learn about raingarden logic. The two most prized trees on the property--evidenced by their stature and the steel cables someone ran up their trunks long ago to serve as lightning rods--are a gorgeous sugar maple near the house and a large white ash along the driveway. As the emerald ash borer advances towards Princeton, the ash will need to be treated with emamectin benzoate, a systemic insecticide injected into the base of the tree every few years. Arbor-Mectin is one of the brand names. A fuller discussion of the issue can be found towards the bottom at this link.

The Updike Farm house is a great example for learning how to site a raingarden on your property. That circle in the foreground is the spot I suggested, in a low spot about 15 feet from the house.

Why that particular location next to the Updike Farm house? Because that's where the house could feed the raingarden in three different ways. For one, there's this pipe which drains a quarter of the main roof. That's a lot of rainwater to feed the garden.

Even better, there's a sump pump that pumps water from the basement out a pipe next to the foundation. You can see the deterioration of the paint at the base of the wall due to that moisture. It would be better for the house, and conducive for a raingarden, to instead pipe that water out to the raingarden location, where it can do some good. A sump pump continues to pump water out of a basement for a number of days after a rain, extending the period during which the raingarden will get supplied with water.

Also auspicious for keeping a raingarden watered, even during prolonged droughts, is the set of air conditioners lined up on that side of the house. Air conditioners remove water from the indoor air as part of the cooling process, and in the basement of the Updike farm house, we discovered that that condensate drains to the sump pump, which then pumps it out of the house. That means the pump could supply water to the garden even during droughts. That consistent, automatic watering will keep the native plants growing vigorously and reduce the weeding required.

Seems like a perfect spot for a raingarden.



The Mountain Lakes House raingarden, similarly sited, is a good model.

More about the Updike Farmstead: If you go out there, or stop by on the way to Route 1, check out the barn renovation.

It's good to see an old building getting the attention it needs and deserves.

A new foundation is being laid.

With the bike trail along Quaker Road completed, it's now possible to bike out to Updike Farm, then continue to the canal,

and bike back to Princeton along the towpath.

Trees On the March

Something's going on in the field down next to Faculty Drive, across Washington Road from the boathouse at Carnegie Lake.

The troops are assembled, like high-stepping Clydsdales poised for the Arbor Day parade. Ready, forward, march!

But where to? The man assigned to water these 20 foot tall specimens said they're all headed into the woods to grow in the shadow of their granddad's generation, just across Faculty Drive, where the university is finishing up its stream restoration in the valley next to the new Chemistry building. (To see a history of the project, type "stream" into the search box at the upper left corner of this website). The university had to take down a few big trees last year (some possibly 200 years old) as part of the restoration of the heavily eroded stream corridor, and looks determined to give their replacements a head start.

The stream restoration is extraordinary in terms of how they created a lovely and hopefully durable streambed, but the botanical side of the project would have been more enlightened if it had included rescue of high quality native wildflowers prior to construction, and invasive species removal on the adjacent slopes.

And though they're putting in the same species of trees they took out--tupelo, pin oak and white ash--the chances the white ash in this photo will survive for more than a decade are pretty remote, given the near certain arrival in coming years of the exotic Emerald Ash Borer now spreading eastward through Pennsylvania.

I was craning my neck to see the thick, paired twigs that identify the tree as an ash, when I realized I could just look at the tag.