A Pettable Blue-Winged Wasp's Mating Frenzy on Princeton Campus

This post gives a demonstration of wasp petting, and describes a funny thing that happened while helping our younger daughter move into her college dorm.

There's a wasp that's both pretty and pretty harmless. It's named after its wings, which reflect blue in the sunlight, and is easily identified by the rusty orange abdomen with two yellow spots. Scolia dubia, as it's called in latin, is a frequent visitor to the boneset in our backyard garden, more methodical in its nectar drinking than many other wasps.

It's understandable that people are afraid of wasps, given the stings most of us have endured after accidentally stepping on a yellow jacket's nest out in the field. But not all wasps are social like a yellow jacket, or even have nests. A female blue-winged wasp (males cannot sting) has no nest to defend, but rather digs down to lay its egg on an underground grub, then leaves the egg to hatch, consume the conveniently paralyzed grub (usually a larva of the June bug or the Japanese beetle), and emerge on its own as an adult.

Here's an example of how docile these creatures are as they peacefully sip nectar.



This year's visits seemed less frequent than in previous years, leading me to wonder how the species is faring, given all the talk of pollinators being in trouble.

That question was answered in the most unexpected way. Helping our younger daughter move into a dorm for her first year at Princeton University, I noticed one of these blue-winged wasps on a flower near the entryway. Then, on the third or fourth trip in with stuff, I happened to look over at the lawn in the courtyard, and noticed that hundreds of the wasps--let's call it an even thousand--were roaming in zig-zaggy patterns just above the grass. It wasn't at all obvious what they were doing. They looked lost, each flying around and back and forth in its own orbit. Perhaps the grounds crew had blocked their nest, leaving them to search in vain for the entrance. One passerby joked that the wasps were a metaphor for incoming freshmen. Another suggested that the University should take action on what seemed like a threat to the students.

My sense was that any danger was more perceived than real. Having spent many hours this summer photographing the various pollinators visiting the backyard boneset, seeing how harmless are the various bees and wasps when preoccupied with other matters, I waded out into the fray to have a closer look. Were they in fact lost? Or hunting? Or mating? There was no sign of prey, and if they were mating, then why was there so little interaction?

The first clue came only after watching them for awhile. Every now and then, some 20 or 30 of the wasps would suddenly converge on one location in what appeared to be a mad scramble in the grass. It's not easy to photograph wasps zipping around your ankles, but I did manage this photo.

And also this video of one of the sudden convergences. If they were fighting, it appeared brief. If they were mating, it looked pretty clumsy.



Some internet research made it clear that the goal of this mass, planar mingling of wasps was to mate. Some websites state that the males and females do a figure eight-shaped mating dance. Others suggest that those cruising the grass are males waiting for a newly mature female to emerge from the ground. They then converge on the female and compete for a chance to mate. If one's heart can go out to a wasp, my heart went out to the hapless female who, having just emerged as an adult from its underground birthplace, must immediately deal with a frenzied crowd of males seeking to pass along their genes to the next generation. If that is true, though, the sheer numbers and intensity of the gathering suggest that a whole lot of hatching was going on that day, and might the males have also just emerged from the ground? The explanations weren't quite making sense.

I did manage to get up close and personal with one of the convergences, close enough for a voyeuristic view of a male and female taking a tumble amidst the grass blades, clearly mating, with another male up next to them, bending its abdomen and probing in vain. What was surprising was how quickly most males gave up on the project, quickly returning to their holding patterns above the grass.

Here's the online description that best fits what I saw, in a 2016 paper entitled "The Scramble Competition Mating System of Scolia dubia" 

Males of the wasp Scolia dubia search for emerging females by flying low over the ground in areas, such as lawns, that contain the immature scarab beetles upon which the grubs feed. When an adult female emerges and is discovered by a searching male, other males often join the discoverer, forming a frenzied ball of males around the female. When captured along with these males by an observer, a freshly emerged female continues to attract males even after she has mated, presumably because her scent continues to be detected by other males. Some males of S. dubia also search for mates in shrubs and trees encircling a lawn as shown by the sexual response of these males to a frozen but thawed female placed in a shrub or tree known to be visited by flying males. Male flight activity peaks around midday but then diminishes as the afternoon proceeds. 

It was in fact late morning, sunny, warm, and some of the wasps were flying about the branches of the evergreen tree in the middle of the field. But there are many lingering questions. Do these gatherings happen only once per year, or multiple times in the summer? Was this lawn special in some way, or does this happen all over town? And how did these rituals play out before lawn mowers were invented?

One thing is clear. These docile wasps do us a favor by preying on a notorious garden pest--the Japanese beetle. Maybe some September, walking home from the Dinky station, you'll cut through campus and some late-flowering thoroughworts will catch your eye. There, in the clouds of white flowers, blue-winged wasps will be busy living their quiet lives, minding their own business while doing good deeds, their solitary pursuit of nectar giving no clue as to the elaborate choreography that brings them into being.

Summer's Last Florrah

In the backyard, the exuberant yellows and brilliant whites of August are mellowing into a more subtle color scheme. The stonecrop, which I'd like to induct into the nativy non-native club, is deepening towards burgundy.

The sunchoke, aka Jerusalem artichoke (Helianthus tuberosa) is showing up late for the party and wondering why so many others

are sporting sober earthtones.

September's late boneset (Eupatorium serotinum) is gracefully extending the white of August's boneset (Eupatorium perfoliatum), though to a much reduced audience of insects.

Goldenrods and New England aster are brightly colored, but

their cheer is muted by the deepening browns of Joe Pye Weed.

Today was as good a time as any to take a measure of this magnificent summer's growth. Cutleaf coneflowers rose to 6.5 feet. The JoePyeWeed topped out at 8.5 feet. The cup-plant in this photo rose ambitiously to 9.5 feet before growing top-heavy and splaying out.

Sunchoke was the undisputed champ, rising to 10.5 feet, even though it was growing in pots.

The big pots, which contain the sunchoke roots' imperialistic tendencies, can be tipped over in the winter to harvest the edible tubers packed inside them. (Idea: Try cutting the tops when they die back, turning over the pot, then lifting the pot occasionally to take a few tubers.) I eat them raw, but a friend heaped praise upon sunchoke soup.

A Giant in the Backyard

There are a number of very tall wildflowers that thrive in sunny, wet ground. Cutleaf coneflower can grow to ten feet. Joe-pye-weed, late-flowering thoroughwort and native sunflowers can reach impressive heights in late summer. But one plant is already towering over me in the backyard.

In the photo is the growing tip of Tall Meadow Rue (Thalictrum pubescens), which, growing at the rate of 2 inches a day this spring, has now reached a height of seven feet, with no sign of stopping.

Tall meadow rue plays a role that is complementary to the boneset described in detail last July. Both grow into vegetative high-rises topped by masses of white flowers that attract a surprising diversity of insect life, with meadow rue doing its work early in the season, and boneset reaching maturity in mid-summer.

Even before flowering, the meadow rue is serving as substrate for the life cycles of the local insect community.

D&R Greenway Plant Sale Thursday

The D&R Greenway is having an exhibit opening tomorrow that will include the first selling of native plants from the nursery they're developing. The plants have been propagated from local genotypes, meaning that these plants carry genetic material from plants that have grown in the Princeton area for millenia. Some characteristics of a native species can vary across its range. Selling local genotypes preserves these special characteristics.
Below is information on the event, and also a list of plants being sold. Most are trees, but there are a couple wildflowers, most notably boneset (see recent posts).


From http://www.drgreenway.org/:

"The Land That Feeds You, Celebrating Farms and Farmers"
- a mixed media art exhibition celebrating agriculture in the Garden State

Join us for the Opening Reception on Thursday, September 25th, 5:30 - 7:30 p.m.
featuring art, local foods and wines.
Featured Speakers: Charles Kuperus, Secretary, NJ Dept. of Agriculture, "Import of Agriculture to the Garden State" and Michelle Mulder, Counsel to Congressman Rush Holt, on the Congressman's New Community Supported Agriculture Bill.

Purchase the first specimens from D&R Greenway's Native Plant Nursery! This event is free, but reservations are requested. Music by Bill Flemer Riverside Bluegrass Band. Art is available for purchase, 35% of the purchase price is a tax-deductible contribution to D&R Greenway's land preservation mission.
RSVP requested: 609-924-4646

Plant List for the plant sale:

Spicebush

Arrowwood

Winterberry

Serviceberry (A. Laevis)

Persimmon

Shagbark Hickory, White Oak, Chestnut Oak, N. Red Oak (all one-year old as they are deep tap-rooters)

Black Birch

Tuliptree

Boneset

Golden Ragwort

Bees On Boneset

The most numerous insects crowding the boneset flowers for weeks on end during this unusually cool August were bumble bees and honeybees. There were also lots of tinier bee-like creatures zigzagging across the plant or landing to feast at length. With those, it was very hard to tell if they were all the same kind or could be distinguished one from another in some way. Note the sacs of pollen on the legs of the honey bees and bumble bees.

These three bees raise the total count to 32.

Getting Close to the Madding Crowd

The party's over. The artesian well of nectar that for weeks on end fed all who made the journey to a batch of backyard boneset is now finally running dry. As can be seen from the crowd in this photo, and the nearly 50 different species shown in the seven previous posts, the plants generated phenomenal buzz in the insect community. It was an extraordinarily diverse gathering, and peaceful. True, a few insects became meals for spiders, but the vegetarian bees, wasps, moths, flies, butterflies and bugs grazed in harmony like herds of megafauna on the great plains of Africa.

You have to admire the ambition of a flower that tries to be, and succeeds in being, all things to all bees. The plant is like a miniature town, its stems and leaves providing cover, and avenues for ladybugs to patrol like Pacmen in an old video game. Bumble bees slept under its blossoms at night, like drunks who can't quite make it home from the local saloon.

Now the deed is done, the nectar drained, the pollen carted off and stowed. Flowers fade and seeds ripen. This Fly-By-Day operation, after mesmerizing the insect world for many weeks, finally closes down, making room for other, later flowering species to step forward and garner attention. As it happens, Late-Flowering Boneset--a different species of Eupatorium scattered here and there across the Princeton landscape--is just opening for business.

Color Begets Color

If you think of a flowering plant as a slow-motion firework, with a summerlong rise up to a shower of color ("Fireworks" is actually the name of a variety of goldenrod), then the goldfinch in this photo is reminiscent of those fireworks that flash in the sky, then send another ring of color out beyond the initial display, like booster rockets. As I approach, the goldfinches rise up out of the cutleaf coneflowers, flashes of gold headed to a nearby tree limb to wait until I leave.

They don't seem to care if the seeds are ripe or not, descending on the seedheads before all the petals have fallen. Being small and lightweight is an advantage when perching on a slim stem.

Other airborne yellows arrive, like this Clouded Sulphur (Colias sp.),

and a tiger swallowtail, relatively common this year, here on a cup plant bloom.

A red-spotted purple (Limenitis arthemis) showed up one day on the boneset.

This yellow-collared scape moth (Cisseps fulvicollis) is a more frequent visitor.

This is the multiplicating capacity of a wildflower garden, to layer interest upon interest. The boneset in particular are like small ecosystems, creating at least a three-tiered food chain of flower, dozens of kinds of pollinator, plus various predators thereof.

Boneset Spiders

Not all the life drawn to boneset is looking for nectar. Nature being what it is, it's only natural that a few predators would show up, lurking just under the blossoms, or building miniature webs. Some are better disguised than others. (It may take awhile for you to find the spider in the first photo.)

Most seem content to sit still, even if a potential prey comes nearby. Maybe they already had a meal before I happened along. Collectively, they extend the food chain at this backyard oasis to three (plant nectar -- pollinator -- spider).

Seven kinds of spiders or spider-like creatures raises the total count to 39.


















The creature in this last photo is who knows what, but doesn't appear to be an insect.

Retention Basin Beauty

Most visitors to Farmview Fields, across the Great Road from Coventry Farm, go there for soccer or baseball. I was there last week to check out the retention basin. It's tucked behind the soccer field, in the far back of this photo, essentially a big scooped out area designed to hold stormwater runoff from the parking lot and slowly release it into the stream, in this case Pretty Brook. They're common in housing and office developments around town, and are usually mowed to look like sunken lawns.

Most don't draw attention, but this one actually has a sign, and is mowed only once a year, if that. To the right of the mowed pathway you can see big bluestem grass leaning this way and that, fine fodder for the woodland bison that once lived hereabouts.

When I was naturalist for Friends of Princeton Open Space, and visiting the park to watch my daughter's soccer games, I decided that the mowed retention basin was an eyesore and a waste of gas. Its short grass wasn't doing a very good job of filtering nutrients and pollutants out of the runoff, and the turf was of little use for wildlife.

Eric Schrading of Partners for Fish and Wildlife came to the rescue, offering to replace the turf with native "warm season" grasses (Indian grass and big bluestem are tallgrass prairie species that do most of their growing during the hot summer months). The effort was federally funded, at no cost to Princeton Township.

Despite the requisite drought (there's always a drought after someone plants a native prairie), many of the grasses grew and prospered, and I added some local genotype wildflowers like Hibiscus moscheutos and late-flowering boneset. Goldenrods came in on their own.

Here's the before shot, in 2006.

Here's the basin last week. The late-flowering boneset (white) has spread, and in the distance is a nice patch of woolgrass (reddish brown) that came in on its own. This is the best shot I have thus far to show the potential for turning drab basins into beautiful habitat.

Last week, the monarch butterflies were clearly in agreement with the change, feasting on nectar in preparation for their long flight south to Mexico.


Note: A post from 2006, prior to this transformation, can be found here. (http://princetonnaturenotes.blogspot.com/2006/12/wetland-arks-in-princeton.html)

Documenting the PHS Ecolab's Recovery From Last Year's Trauma

Passerby on Walnut Street may have noticed that the Princeton High School Ecolab wetland was completely stripped of vegetation by an outside contractor this past November. After the shock of having so many native shrubs and wildflowers suddenly gone, it took us awhile to realize that the roots of the native plants might still be alive beneath the bare dirt. Having lobbied successfully to have stewardship of the Ecolab returned to the teachers, students, and volunteers who had cared for it free of charge for fifteen years, we are watching for signs of its rebirth. 

Most obvious is the annual grass planted by the contractor for erosion control. But I took a closer look and found gratifying evidence that the wetland will rebound. Click on "Read more" below to see a photo inventory of 40 native species (and a few very manageable weeds) that have popped up thus far, ready to refoliate this wonderful teaching resource for the school's environmental science program.

Princeton Raingarden Update

Many people have asked me for an update on the raingarden that was bulldozed at Spruce Circle on Harrison Street this past August. The loss of the raingarden, planted on Housing Authority land next to Harrison Street, came as a shock, given I'd been taking care of it for six years. The story gained considerable additional attention when my post was published on the local news site, PlanetPrinceton.com. Since the Housing Authority's apology a week later, I have been working with Housing staff and others to develop a plan not only for replanting of the original raingarden, but assessment of other locations where raingardens could be planted as well.

The aim of these plantings goes beyond aesthetics. The importance of pollinators for food security is more in the news lately, as is the uncertain fate of the monarch butterfly's miraculous migration. All of this is getting people to look at landscapes with the needs of pollinators in mind.

That's what we were doing at Redding Circle last week, in a detention basin at the corner of Ewing Street and Mount Lucas, hidden behind a fence, where the runoff from a Housing Authority complex accumulates before being piped into Harry's Brook. "We" was Housing facilities staffer Jim, Brian Marsh of Partners for Fish and Wildlife, Heidi Fictenbaum of the Princeton Environmental Commission, and Greg O'Neil of Princeton public works. Heidi, in an initiative parallel to my own, has developed an inventory of Princeton's many detention basins, with the aim of retrofitting as many as possible for habitat.

The question being pondered was how to turn a detention basin filled with exotic fescue, stiltgrass, and invasive porcelainberry vines into a foodfest for pollinators, while actually reducing the maintenance Jim and his staff need to do.

When standing in a rather drab detention basin talking for 45 minutes, it helps to be all the while visualizing a field full of New England Aster and late boneset, like these that are prospering along Nassau Street in front of the Whole Earth Center. The magic of raingardens and their larger cousins, detention basins, is that the soil is more frequently wet. That wetness means easier planting and weeding in the soft soils, less followup watering, and increased chance that the native species so well adapted to growing in wet, sunny ground will thrive.

We came up with a plan, jotted down and sent around by Heidi: Reduce mowing to once every year or two, knock out the porcelainberry vines, plant native wildflowers in the wettest, lowest part of the basin, and close the gate so the deer have a harder time getting in.

I then took Brian--whose federal Partners agency has helped with basin conversions in the past--at the Princeton High School and at Farmview Fields--on a whirlwind "great basins of Princeton" tour, to see if we could turn additional basins into aesthetic feeding stations to support pollinators. The massive one in this photo is just up from the Charter School. Again, it helps, when looking at this mass of undifferentiated turf with its existential "sidewalk to nowhere" running down the middle, to imagine schoolkids helping to plant shrubs and wildflowers, and returning the next year to learn about the sorts of pollinators that make their lunch possible.

Next stop was Smoyer Park, which has a promising basin that receives runoff from the parking lot. A meadow would provide better filtration of the runoff than a mowed lawn. We also visited a basin out Rosedale Road at Greenway Meadows.

Unfortunately, Partners for Fish and Wildlife, like most federal agencies, have been hampered by Congress' sequestering of funding, so may not be able to help out as much as in the past. Still, there's a chance they can do enough to kickstart this local initiative.

Meanwhile, back at the Spruce Circle location, replanting of the bulldozed raingarden could include replacement of these winged euonymus shrubs, which are constantly overgrowing their location and have made for a jarring visual behind the rain garden. To be planted in their place, if the plan is approved, would be something similar to this--a mix of Virginia sweetspire, Fothergilla, highbush blueberry and oak-leaved hydrangia.

The moral of this story, still early in the telling, is to turn lemons into lemonade. Or, for those who think like a pollinator: turn turf into nectar.

Related post from 2012.

Urban Beekeeping

An interesting article on growing honey bees in the city. It's now legal in some places. I know someone who has a beehive in his suburban garage, with a little hole in the back wall for them to come and go.

In particular, one beekeeper interviewed says that, if you grow bees, you start thinking like a bee and want to transform the landscape to make it more bee-friendly. If there's a beekeeper in the neighborhood, fruit trees bear more fruit, including arctic kiwi--a frost tolerant version of the fruit that grows in northern latitudes. (A friend tells me at least one Princeton resident is growing them--kiwis, that is--with very good results.) Bees, then, can help in the process of re-imagining a neighborhood.

I was surprised to learn, back in the early '90s when the honeybee population crashed due to an introduced mite, that honey bees are not native to America. The photo, from a 2008 post, shows a couple honeybees mixed with some native pollinators on the flowers of boneset, a native wildflower that becomes the insect world's favorite food court every August.

Chain Saw Gardening--the Sequel

A couple weeks ago, after witnessing the now neglected gardens planted at Harrison Street Park three years ago, I walked over to the Whole Earth Center, where a man was trimming the raingarden with a chainsaw. I didn't ask him to pose for a photo, but you can see plant debris littering the sidewalk.

A clipped bit of soft rush, no match for a chainsaw blade, was being held up for examination by the resident frog. It seemed inauspicious, that a garden I had installed a few years back was being given the chainsaw treatment. It happened last year with another raingarden down the street. But this time around the chainsaw treatment didn't go much beyond trimming back some of the native mistflower that had been leaning out over the sidewalk.

Strange to say, this garden is actually prospering despite the complete lack of coordination between the various entities who care for it. There's the crew hired by the out of town landlord, which lays down fresh mulch in the spring and this year added the chainsaw to its arsenal. In addition, there's someone on staff at the Whole Earth Center who does occasional watering, and then I stop by when I think of it, adding a few plants here and there. Some of what I plant gets smothered by the mulch, or gets pulled out unwittingly by the landlord's crew, but actually communicating with the other caretakers would be harder than dealing with the periodic setbacks.

Its success comes also from an auspicious hydrology. Roof water, which normally would go directly from the downspout out into the street, is instead funneled through a perforated pipe running just underground along the garden's full length. This extra dose of water allows the fringed sedge, soft rush, buttonbush and mistflower to prosper.

Before this was a garden, it was an elaborate sculpture of wooden stumps and logs installed by Peter Soderman. From what I heard, the fire officials took exception to all that wood next to a building, so only a couple pieces remain.

If I had thought of it, I might have suggested the man with the chainsaw trim back the pre-flowering stages of cutleaf coneflower and boneset on either side of the flowering oakleaf hydrangia. They'd simply bloom a little later, and be less likely to flop over. But who knows what a little encouragement would cause him to do next time.