Ambush Bugs: Hidden Dangers for Pollinators

During an evening stroll in the backyard garden, with a big show of fireflies soon to come, we were admiring a common milkweed's blooms--like frozen fireworks at lawn's edge--when my friend spotted a honeybee on one of the flowers.

Isn't this the way it's supposed to be? You plant native wildflowers and the pollinators show up to feed ever so gratefully. But something didn't look quite right to me. The honeybee wasn't moving. 

Maybe it was memories of blog posts ten years ago--written after standing for hours gazing at the extraordinarily diverse community of insects and spiders drawn to boneset flowers--that caused me to take a closer look at that motionless honey bee. 

There, beautifully, mischievously, mercilessly camouflaged, hiding between the milkweed flowers, were two pairs of ambush bugs, mottled brown, black and white. The smaller of each pair sat atop the larger, apparently mating. Life is short for an insect, so it seems perfectly practical that one of the females, needing nourishment for whatever eggs come of the mating, had chosen that moment to snag the honeybee whose bad luck it was to visit those particular flowers.

Later, I returned to try for a better photo of the ambush bug and its mate.

By then, they had consumed what they wanted of the bee, dropping the remains to land ever so lightly on a leaf, one story down in the tower of milkweed.

Afternote: One could probably spend a lifetime exploring the mechanisms behind the camouflage of an ambush bug, as this quote from the Missouri Department of Conservation website shows:

"The colors of ambush bugs are worth mentioning. They can vary quite a bit within a single species. Most are gold, yellow, leaf-green, tan, brown, or white, often with dark mottled patches or bands. Apparently males are often darker or more spotted than females. It’s not clear whether individual ambush bugs change color like chameleons (and some crab spiders) to match the plants they’re resting on, or if they simply move to (or survive on) plants whose colors happen to match their bodies. It could be that they change color with each molt: young individuals, early in the season, being pale green, matching the new foliage of springtime, while older specimens become gold and black in later molts to match the flowers that develop in midsummer. The temperatures during egg stage may also affect the overall darkness of the insects."

Witnessing a Spongy Moth Outbreak Along the Appalachian Trail

I wasn't expecting to run into an outbreak of spongy moths (formerly called gypsy moths) in New Jersey earlier this week. The aim of driving up to the Stokes State Forest near Delaware Water Gap was to drop off my younger daughter Anna so she could resume her thru-hike on the Appalachian Trail. 

After a couple day visit at home, Anna was eager to continue her journey northward towards Maine. When we reached Sunrise Mountain Overpass, she asked if I wanted to hike along with her for a bit. 

It was as if she had invited me into her home, which the AT has been since she began in Georgia back in late February--more than 1000 miles thus far. Everything she needs is in her backpack--designed to be lightweight but still very substantial--as she hikes up and down mountain after mountain, rain or sunshine, cold or hot, following America's verdant eastern spine through North Carolina, Tennessee, Virginia, West Virginia, Pennsylvania, and now just the northwestern tip of NJ before heading into New York state. 

Most of the inspiring vistas she sees along the way are not tempered with a warning about venomous snakes, like this one at the parking lot. New Jersey is unusual in having venemous snakes in the north and south of the state, but not where we live in central Jersey. As for black bears, over three months she has seen only one and heard another. Though she started the hike on her own, there's now a group of companions with whom she camps each night.

As we hiked the rocky trail, we had to look mostly down to avoid the stones, stealing glances at the high quality woodland, free from invasive plants except for an occasional garlic mustard. We soon became aware, however, of an odd noise that sounded like a light sprinkle, despite the clear sky. When I turned back, leaving Anna to head north on her many steps towards Maine, I started taking a closer look at the leaves of oak, sassafras, and maple above. The well-munched leaves were surely a very generous giving of tissue by the trees to the local insect population. 

But what was that sound of rain with no rainclouds in sight? And why was the ground littered with fragments of green leaves? Whatever was eating the trees was being messy about it. 

Then I felt something very light fall on my head. I brushed it onto my hand, gave it a good look, and decided to call it frass, that is, caterpillar droppings. 

On the ground all around, the leaf litter had been in turn littered with this frass, raining down from far above.

Though most of the caterpillars remained unseen high in the canopy, a few were close enough at hand to get a photo. 

Back home, searching the internet, the caterpillar's identity quickly became apparent: spongy moth, also known as Lymantria dispar dispar, and formally known as "gypsy moth."

One source described exactly our experience along the trail:

"(Spongy) moths are invasive insect pests that can be destructive to trees, especially hardwoods like oaks. In May and June, each caterpillar can grow up to two inches long and consume 11 square feet of leaves. Signs of a (spongy) moth outbreak include bare tree canopies, droppings that sound like rain, and leaf confetti on the forest floor."

If you haven't heard of spongy moths, or haven't heard of them in a long time, it's because this highly destructive introduced species is no longer causing widespread havoc in our forests. thanks to the development of a remarkably successful, low-toxicity treatment. 

Imported into Massachusetts from Europe in 1869 with the intent of starting a new silk industry in America, the spongy moth escaped into the wild and was soon causing dramatic defoliations of forests. Though oaks are a favorite, spongy moths threaten a broad range of species, including both hardwoods and conifers. One source alphabetically describes its diet this way:

Preferred: Alder, apple, aspen, basswood, birch, hawthorn, oaks, tamarack, willow, witch hazel
Intermediate: Beech, dogwood, elm, hemlock, maple, pine, Prunus species, serviceberry, spruce, walnut
Avoided: Ash, balsam fir, cedar, red & white, locusts, mountain maple, pine, scotch

According to numerous articles found on the Papers of Princeton website, 13 years of intense spraying led to eradication of the spongy moth in NJ by 1932, but it reappeared in 1953 and by 1955 had again become a serious pest. In 1965, a small area near Mt. Lucas Road in Princeton was sprayed. As defoliation increased statewide through the 1970s, the most common treatment--carbonyl, also known as Sevin--became suspect due to its effect on honeybees. 

Letters to the editor describe heroic citizen efforts to round up and destroy the moths' egg cases. Elizabeth Carrick, chairman of the Woodfield Reservation Committee, described a successful outing by girlscouts in 1972. In 1980, Preston and Helen Tuttle reported on a hand collection campaign in the Institute Woods that included renowned faculty at the Institute for Advanced Studies:

During the past two weekends. 95 individuals, ranging from Girl and Boy Scouts to world-famous mathematicians, took part In all. 8.791 egg cases were collected or immobilized witn a hand held sprayer containing a mixture of creosote, turpentine and transmission fluid This was used to spray those egg masses that were above convenient scraping and collecting reach Egg masses collected the first weekend were given to the state Biological Controls Laboratory to feed spongy moth predators being developed by the state.

Destruction peaked in 1981, when 12 million acres were affected by defoliation nationwide. The biggest reason we haven't heard much about this hugely destructive pest lately is the utilization of a low-toxicity bacteria called Bacillus thuringiensis (Bt). First mention of it in local papers appears to have been in 1974. Bt is sprayed on foliage in the spring. When eaten by the caterpillars, it disrupts their digestive systems. By 1990, arborist Sam deTuro of Woodwind Associates, who used to have a regular column in the Town Topics, was combining the traditional chemical spray methods with a new formulation of Bt.

Like the many mountains and valleys of the Appalachian Trail, moth numbers have risen and fallen dramatically through the decades. Spongy moth numbers in NJ reached a relative low in 1988, only to rise 19 fold in 1989. Another peak came in 2008, prompting aerial sprays of Bt in Princeton. 

Numbers have dropped since then, leading many of us to forget about spongy moths altogether. For that luxury, we have a state government program to thank. The New Jersey Dept. of Agriculture has been running a   spongy moth suppression program at least since 2007. In 2024, they planned to spray 3000 acres of local and state-owned land. The aim is to prevent repeated defoliation of forests. Trees that can survive defoliation one year may not be able to survive defoliation two years in a row. The state description sounds like what governments are supposed to do--work collaboratively to intervene in safe ways to protect us and our environment. LDD stands for the species name, Lymantria dispar dispar.

The New Jersey Department of Agriculture promotes an integrated pest management approach, which encourages natural controls to reduce LDD feeding and subsequent tree loss. However, when LDD cycles are at a peak, natural controls have difficulty in preventing severe defoliation. In these special cases, the Department recommends aerial spray treatments on residential and recreational areas using the selective, non-chemical insecticide, Bacillus thuringiensis.

The Department's LDD Suppression Program is a voluntary cooperative program involving New Jersey municipalities, county agencies, state agencies, and the USDA Forest Service.

17 miles down the trail, Anna was still hearing the curious rain of frass all around, Hopefully the state program of spongy moth suppression will continue to work--an all-too-rare example of successful containment of invasive species threatening our forests.

Below, some sights seen during my short hike on the Appalachian Trail:

Expanses of sedge meadow that can give healthy forests a natural park-like appearance.

The striped maple, Acer pennsylvanicum, is a little tree that grows all along the Appalachian Mountains.

If you hike northward on the AT with the spring, much of your journey will be graced with the blooms of Mountain laurel, Kalmia latifolia, abundant on rocky slopes.

Beech Leaf Disease Sweeps Across Princeton

Princeton is losing its beech trees.

We were feeling celebratory, having just completed a successful corporate workday in Herrontown Woods, when I happened to pass by this small branch of a beech tree along the red trail. The leaves were strangely contorted, with dark green stripes. I had heard distant rumblings about a disease of beech trees, but had managed to keep my head in the sand until that moment. 

Back home, diagnosis was but a google's search away. Similar images popped up on the screen, along with the name: Beech Leaf Disease. Tree maladies typically come with an acronym. Emerald ash borer is EAB. The dreaded asian longhorned beetle, which they've had some success keeping from spreading across the eastern U.S., is ALB. The Bacterial Leaf Scorch that afflicts pin and red oaks is BLS. Now there was a new one: BLD. 

For those unfamiliar with the American beech (Fagus grandifolia), it's a native tree related to oaks and chestnuts, with beautiful smooth gray bark. They can get very big and live for centuries. Thousands of them grow in Princeton, in the preserved forests along the Princeton ridge and on slopes above the Stony Brook. 

The "grandifolia" in the latin name refers to the leaves, which are larger than the leaves of European beeches. This photo shows some healthy leaves (on top) and the curled, darker green leaves that have been contorted by nematodes overwintering in the buds. Beech leaf disease is caused by these nematodes--tiny worms spread by birds or the wind. 

Viewed from beneath, the infected leaves show a curious striping of dark and light green. 

During a subsequent hike in Autumn Hill Reservation, I was astonished to find nearly all the beech trees affected--their leaves contorted, their crowns beginning to thin. Beech in Rogers Refuge are showing symptoms, and Mountain Lakes preserve is reportedly also affected. According to online sources, essentially all of our beech trees will be dead within ten years. The news comes exactly ten years after the first emerald ash borer was found in New Jersey, with the skeletons of ash trees still haunting our woodlands.

According to this map, on the Holden Arboretum website, the disease was first spotted near that arboretum in Ohio in 2012, and has spread in all directions, most rapidly eastward.

According to the Maryland Extension website, the microbe causing the disease is Litylenchus crenatae mccannii, a subspecies of a nematode found in Japan. As one would expect, the only beeches resistant to this particular nematode are those that coevolved with it in Japan. 

The Holden Arboretum website mentions a chemical treatment that is being tested. It is a compound that is sprayed on the tree in the fall just as the nematodes are moving from the leaves down into next year's buds. Unfortunately it is highly toxic. The snail's pace of tree research compared to the rapid development of Covid vaccines caused one friend to ask, "Where is science when we need it?" 

The loss of a tree species from the canopy has all sorts of impacts on wildlife. Ash, elm, and maples bear abundant seeds early in the season to feed on. Two of those three have been largely lost. Nut-bearing trees provide food in fall and winter. Gone from wildlife diets are chestnuts, bacterial leaf scorch is reducing oak production of acorns, and it now looks like beech nuts will become very rare. Websites detail the ecological web of connection and dependence that is unraveled by the loss of a tree species. 

A post last year by the Brandywine Conservancy in Pennsylvania provides a particularly chilling description of what is in store for eastern forests:

"As the disease progresses, leaves will become smaller in subsequent years, and it will seem like autumn in the summer as infected leaves brown and fall from the tree, resulting in thinned crowns and branch dieback. Eventually, BLD will cause beech trees to abort their buds, leading to the death of the tree. Young beech tree saplings die within 2–5 years of infection, while mature trees live a bit longer. Death from BLD is likely accelerated in beech trees stressed by drought or Beech Bark Disease, which is a different infection that involves scale insects and fungi."

Here's a writeup I found on beech bark disease, which also poses a mortal threat. 

I encourage people to visit favorite beech forests in the area sooner rather than later, to appreciate the now threatened beauty of this singular tree. Over the next few years, if you are fortunate enough to find one that remains healthy while others around it succumb, you should let people know. The Holden Arboretum site provides someone to contact.

Yesterday evening, I visited the fabulous congregation of European beech off of Elm Lane on Constitution Hill in western Princeton. The many trunks appear to all come from the original massive trunk in the middle. 

Seen from a distance, they appear to be separate trees, but more likely were either branches that touched the ground and took root, or sprouts from the original tree's massive root system.

You can see how some of the trunks still have a sort of navel, where the original branch from the "mother tree" was cut off.

Its leaves, smaller than those of the native beech, were  showing early signs of the disease.

Some of Princeton's most spectacular native beech trees grow in the Institute Woods. That will be my next stop--that and a hidden valley between the Princeton University chemistry building and Washington Road, where I found a mixed forest of 200 year old trees, part of the great American forest cathedral that, in unspeakable sadness, loses its towering pillars, one by one.

Here is how I concluded a recent letter to the editor in the Town Topics: 

Outrage is often triggered by the intentional cutting of trees. The highly visible spotted lanternfly caused a stir, yet has proven relatively innocuous. The biggest threats we face are neither visible nor intentional. The emerald ash borer is hidden behind bark. Nematodes are microscopic. Our machines’ climate-radicalizing carbon dioxide? Unintended and invisible.

There is so much joy still to experience, for me particularly in Herrontown Woods, and yet in the larger workings of the world, so much to grieve.

A Winsome Bugloss-Wood Poppy Combo

There's a winsome duo--one yellow, the other blue--that I first saw blooming together in my friend Gail's garden. I don't think my having two degrees from the University of Michigan has anything to do with their blue and gold appeal, though the blue one I first encountered in Ann Arbor. Though one is native and one is not, I think of them both in the same breath. They both thrive in moist soils and some shade, and combine attractive flowers with attractive foliage. Both spread by seed, not rampantly but just enough to create a sense of delight at the sight of a new one having popped up here and there. Both have common names that can get in the way of fully enjoying them. Neither grows in the wilds of Princeton that I have ever seen. 

The first is Siberian bugloss (sounds best when pronounced "BOO-gloss", a perennial that, as its name suggests, is native to Siberia, south to the Caucusus. It has tiny blue flowers and,

as its latin name Brunnera macrophylla suggests, large leaves that remain attractive through the growing season. The name "bugloss" comes from Greek, meaning 'ox's tongue', referring to the leaf's shape and rough texture.

The large leaves and clouds of blue flowers mix well with other garden plants, in this case a largely random congregation of hostas, mayapples, and day lilies.

They also mix well with a native yellow flower called wood poppy. I'd call it by its other common name, celandine poppy, but that creates confusion with the super invasive lesser celandine. 

The diphyllum in its intimidating genus-species name, Stylophorum diphyllum, also refers to the leaves. After the flowers are gone, the foliage forms a nice mound through the summer 

that fits in well with other plants like Christmas fern.

Wood poppy has a nonnative invasive look-alike called greater celandine (Chelidonium majus) that I've only found a couple small patches of in the Princeton area. 

As this comparison shows, wood poppy has larger flowers. 

And wood poppy has hairy seedpods like these, while greater celandine's seedpods are smooth.

Siberian bugloss also has a look-alike, this one with a much more appealing name: forget-me-not, which has tiny leaves and lighter blue flowers. Its genus, Myosotis, also draws from animal anatomy: it's Greek for "mouse's ear."

A few times I've had to break the news to gardeners that the lovely flower they've been growing and admiring in their gardens is not the endearingly named forget-me-not, but instead Siberian bugloss. 

Siberia, bugs, loss, ox's tongue--these are not the associations people wish to conjure when admiring such a pretty plant. The sometimes used "false forget-me-not" doesn't land well either.

Other common names for the plant that are far less common but far more palatable are "great forget-me-not" (they're both in the borage family, after all) and "heartleaf Brunnera."

The plants are easy on the eyes and easy on the garden; but the names can get in the way.

Campus Grounds Sprout Local Flora

Some areas of Princeton University's intensely landscaped campus are starting to sprout local native flora. Using native plants doesn't necessarily mean those species will be found in local nature preserves. Many native plants popular in landscaping--purple coneflower, red buckeye, bottlebrush buckeye, oak-leaved hydrangia, witch-alder, Virginia sweetspire--are seldom or never seen growing on their own in the local wild. 

But recently, the University has been planting the actual species frequently encountered in local nature preserves like Herrontown Woods and Mountain Lakes. This spicebush shrub in front of the Lewis Center for the Arts, 185 Nassau Street, resonates with the spicebush  so common in our woodlands.  

 

Turf has been replaced with a sedge meadow, probably the same Pennsylvania sedge that can be encountered in remnant meadows in local woods.

Masses of Christmas fern now grow on campus as they do along the slopes of the Princeton ridge.

A few species, like the foamflower making this mass of white, are rare to nonexistent in local woodlands, but the overall trend seems to be to treasure what is authentically local. 

Though some of the University's early efforts to plant native landscapes became overrun with weeds, this 2-3 year old planting down near Robert's Stadium is thriving. Better soil prep and thick mulch (and more knowledgeable gardeners?) have, at least thus far, conquered the weeds. The native species chosen are again those one finds in the local wild: cutleaf coneflower, arrowwood Viburnum, and wild rye grass. 

People naturally want to plant things that are special, and special used to be defined by distance--as in exotic plants imported from distant continents. Distance made the botanical heart grow fonder. It's heartening to see a shift in what is viewed as special, towards a valuing of what is truly local.  

Chimney Swifts Converge on a Tower Near You

Updated 5.18: The back side of an abandoned school building doesn't seem an auspicious place to spot endangered wildlife, but check out that chimney. It changes everything.

In a recent letter to Town Topics, Princeton ecology professor Andy Dobson invited readers to witness one of nature's more remarkable annual phenomena, playing out in and above the tower of the old Valley Road School. From his letter:

In the half hour after sunset, several hundred swifts will be “turning and turning in a narrowing gyre” centered around the tower of old Valley Road School building behind Conte’s Pizza. It is quite a spectacular sight as the rapidly spinning circle of birds “know exactly where it leads, and you can watch them go ‘round and ‘round each time.” Suddenly, they will begin to drop down and disappear into the tower to roost for the night. “Wait ‘til you see half the things that haven’t happened yet.”

Andy encourages us to "come to the playing field on Valley Road and enjoy a truly remarkable local wildlife spectacle." 

"They will probably be there at dusk for the next couple of weeks while they pair up and locate nest sites on local tall buildings. The site is Princeton’s equivalent of the Serengeti wildebeest crossing the Mara River on their annual great migration."

His letter was published on May 8, and in typical fashion I didn't get myself over there to have a look until 9 days later. When I arrived, right at sundown, there was nothing to be seen--a golden opportunity for self-rebuke--but just as I began to leave, a high-pitched cheeping somewhere above pulled me back. They came, a few at first, then many, swooping down on the chimney only to veer away at the last possible moment. There is no clear choreography to their acrobatic flight, as they head off in all directions at great speed, sometimes in pairs but mostly on their own, each one's acrobatic flight describing a broad circle out across fields and rooftops, always to return to play yet again with the magnetic pull of the chimney. As the light fades, their gleeful independence ultimately yields to the collective impulse, drawing them down into the chimney's depths to spend the night.

   

Here's a link to Andy's wonderful letter. And here is a link to local writer Carolyn Jones' well researched article on our local chimney swifts and the longterm threat redevelopment of the Valley Road School site poses to their very specialized habitat. 

Andy's comparison of chimney swifts to the migration of the wildebeests that he studies in Africa has added meaning for those of us who have seen the university as often detached from the community of which it is a part. He recently began teaching a course called "Woods and Rivers of Princeton." The course gets students out exploring local nature, and has become so popular that this coming fall's course is triply over-subscribed. This valuing of the local is gratifying to see, and I like to think is part of a larger trend. 

Update, 5.31.24 Andy reports that "the swifts are still there, numbers declining as they pair up and locate nest sites. They should be back by the middle of August in even larger numbers with young of the year."

Helping Herrontown's Beauty Express Itself

There's a lot of built-in beauty at Herrontown Woods. Rocks, wood, and water serve as the basic infrastructure upon which other beauties are overlaid. 

This time of year, it's the understory that gets to shine, just before the tree canopy envelopes the woods in shade. Much of the habitat restoration work we do at Herrontown Woods involves bringing back the beauty and functionality of the native flora. By removing nonnative invasive shrubs that clog the understory, we open up vistas and release the existing native flora from stifling competition. In a sense, we are filling in for the deer, which chow down on native shrubs while leaving the nonnative shrubs uneaten.

Walk up the new boardwalk from the main parking lot to witness a corridor brightened by flowering dogwoods, 

and hundreds of blackhaw Viburnum shrubs adding clusters of white flowers extending deep into the forest.

Redbuds can't survive in the deep shade of the forest, but they proliferate on the more open Veblen House grounds.

This year, we spotted two wild azaleas blooming along Herrontown Road. Fifty years ago, it would have sounded strange to be excited about a couple wild azaleas in the preserve. They were numerous back then, but have been literally laid low by increasing deer numbers and deepening shade. 

It's taken more than a decade of ramblings in the preserve to realize that some kinds of native shrubs we thought long gone in fact remain numerous on the forest floor in miniaturized form, browsed before they can grow sufficiently to bloom. The town's deer culling program has helped native shrubs like spicebush to rebound, but for some species, additional effort is needed.

Protected by cages and given some sun, pinxter azaleas, serviceberries, and hearts-a-bustin' are making a comeback in the Botanical Art Garden (Barden) next to the main parking lot. New plantings of native buttonbush, silky dogwood, pussy willow and elderberry are also being protected until they can grow and flower beyond the deer's reach.

In these ways, we help another layer of beauty in Herrontown Woods to express itself.