Monday, September 30, 2019

A Buttercup Oil Beetle Plays Dead

Walking past the Veblen Cottage at Herrontown Woods, I happened to look down and saw what appeared to be a large blue ant navigating through the grass. As I stooped to take a closer look, it took a charming pose on a leaf. Turns out that kink in the antenna means it's a male.

Various google searches yielded nothing similar, until I made reference to its large blue abdomen. Turns out it is not an ant but a buttercup oil beetle (Meloe americanus), a kind of blister beetle containing oils with a toxin called cantharidin that can cause one's skin to blister.

The beetle played dead, a useful strategy in this case, as it caused us to lose interest and walk away.

Seems like every kind of insect has an interesting lifestyle. This one's larva climbs up a plant, then hangs out on flowers, waiting to catch a ride home on a bee's back where it munches on the bee's provisions and young. It can't be just any kind of bee--each kind of oil beetle must hitchhike on a particular genus or species of bee.

Not much has been written about them, but here's a fun post by a graduate student in NC who found one in her apartment.

Does a buttercup oil beetle prefer to hang out in the flowers of buttercup? Something to contemplate while tip-toeing through the buttercups around Veblen Cottage next spring.

Friday, September 27, 2019

Urban Succession--Butler Apartments Turned Into Meadows

Normal urban succession proceeds from grassland to shrubland to woodland, then to a climax community of houses and lawns. Near the corner of Sycamore and South Harrison Street, a much different sort of succession took place three years ago. The Butler Apartments had stood here since they were built in 1946 in a scramble to house returning veterans, then were later turned into graduate housing. Seventy years later, they were torn down and turned into meadows--real meadows, not some development called The Meadows that names itself after what no longer exists. The scattered trees give the place a savanna-like look, and the preserved infrastructure of streets and fire hydrants serve as a deluxe means to appreciate and care for the plantings.

At the urging of my friend Kurt, I finally paid a visit. I happened to be teaching a 16 year old to ride a bike, so we parked the truck on Sycamore and explored this ultra safe biking territory.

When creating meadows, it's common to scatter "wildflower seed" with species that create a burst of color the first year, but are not native to the area. Surprisingly, this planting reflects closely the local flora, and has been flourishing with all the rain this year. A few of the usual invasive species have gotten small footholds, but the meadows are still dominated by a diversity of natives.

What follows here is a sampling of the plant diversity that can now be found there, and will help with identification for anyone who goes there. In this photo, a maple is turning color early, and doing a dance with a powerline that may or may not still carry electricity.

Korean dogwoods, leftover plantings that still adorn the streets, offer edible fruit at many of the corners.

The white clouds of late-flowering thoroughwort set off the more colorful wildflowers nicely.

Common milkweed sometimes caters to the needs of monarch caterpillars.


Oxeye sunflower, which is common in seed mixes though I've never seen it growing wild.

Grasses to be encountered are Indian grass, switchgrass, purple top, and this shorter one that matured earlier in the year, which is looking like a robust version of wild rye.

In the background is mugwort, a highly invasive species that would likely continue displacing natives if this site is kept as meadow.

I call this frost aster.

Various goldenrods.

This is looking like Japanese hops--an invasive vine, though not nearly as invasive as the kudzu-like porcelainberry, which hopefully has not gotten established here.

Mistflower (wild ageratum) is a native occasionally found in the wild. It grows low to the ground, and can survive only along the edges, given all of its tall competitors here. Eupatorium coelestinum in latin.

Crown vetch is an invasive just beginning to show up.

This is looking like a tickseed sunflower (Bidens)--an annual that can get large and showy, but also can be a bit weedy.

It's been a good year for partridge pea, another native that tends to be rare in the wild but performs really well in these meadow seedmixes.

These monarchs are fueling up at a New England aster waystation prior to making their annual journey to a mountain range in Mexico for the winter.

Pokeweed, also called inkberry for its dark berries. In springtime, there's a way to harvest and prepare "poke salad" so that it is edible, but not the berries.

Other typical wildflowers to look for are wild bergamot, mountain mint, and wild senna.

Eventually this meadow could be shaded out by trees or undone by new construction or the expansion of a few nonnative species, it is currently a great example of a meadow packed with mostly native species growing in balance. Thanks to my friend Kurt for finally getting me over there.

Thursday, September 19, 2019

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.

Friday, September 13, 2019

Attracting Pollinators With Boneset and Thoroughwort

Many people sing the praises of mountain mint and goldenrod for attracting pollinators, but my two favorites are a duo that produce large disks of small white flowers for a long stretch in mid to late summer.

This has been a banner year for boneset and its more numerous but lesser known sidekick, late-flowering thoroughwort.

With a name that spreads like the pagoda-shaped stems that carry its flowers, late-flowering thoroughwort adorns the sides of roads and railroads this time of year. I've seen it cover a whole abandoned field in Montgomery,

and there's a lone specimen blooming at the end of the track at the Dinky station.

It could be called a successful weed, and sometimes it can look a little ragged, perhaps influenced by how much rain comes. But this year it was the most elegant plant in the garden, its loose clusters of flowers like delicate hands reaching out to pollinators.

Late-flowering thoroughwort (left in this photo at the Westminster parking lot raingardens I care for) blooms just as boneset (right) is fading, which this year made for a seamless handoff between the two. Though boneset is comparatively rare in the landscape, it will make seedlings to increase its numbers when planted in a garden.

The two species can easily be told apart by checking the leaves. Boneset has pairs of leaves that are "perfoliate", which is to say they fuse to wrap around the stem. Thus the latin name Eupatorium perfoliatum.

By contrast, the leaves of late-flowering thoroughwort have petioles that extend the leaf away from the stem. The "serotinum" in its latin name, Eupatorium serotinum, means late summer. We could call it the serotinal thoroughwort, but we don't. In the common name, the word "wort" means plant, and if there's anything thorough about a thoroughwort, it's the copious blooms.

Both these wildflower species rise each year to the perfect height for viewing all the varied insect life they attract. Spend some time in that honey-scented space around the flowers and you'll discover an ecosystem in miniature, the flowers being a stage where the protagonists not only feed on nectar, but also look for mates, and sometimes put their lives on the line.

You might think it dangerous to be in proximity to the many kinds of bees and wasps that frequent this floral saloon, but I have never been stung in all my hours immersed in quiet observation.

I've even taken to petting the more docile creatures, like this "solitary" blue-winged wasp. Knowledge can cut through fear. It helps that the more aggressive insects, such as "social" wasps like yellow jackets, spend their summers elsewhere.

If anything, the pollinators are at much greater risk than I, with an occasional preying mantis showing up to snare a fly,

or a brilliantly disguised ambush bug lying in wait for a bumble bee.

Here's the ambush bug that was hiding in that previous photo.

Each plant has a time-release approach to flowering, with some clusters of flowers opening just as others are fading. Week after week in the summer, working in tandem, boneset and late-flowering thoroughwort continue to play host to a shifting cast of insect characters--each with its own traits, backstory and motivations--all the while adding ornament to the garden.

Monday, September 09, 2019

A Lost Public Garden

There's a planting in the field at Turning Basin Park, across the street from the canoe livery. It looks like a curved hedge, but if you take a closer look, there's a sign buried in the foliage.

A butterfly garden was planted there years back, and a lovely sign erected to commemorate the effort. It was a good idea, a nice gesture, and then everyone went their separate ways.

A decade ago, helping WaterWatch with annual workdays at Turning Basin Park--part of Princeton University's freshmen bonding activities before the semester began--I noticed the forsaken garden and spent some time cutting down the woody growth that was starting to shade out the flowers. Each time it took no more than a half hour of skilled attention to discourage the weeds enough to keep the garden blooming for another year.

But WaterWatch passed into history, and with it my annual prompt to volunteer some care for this garden. Up grew the mulberry trees,

and the catalpas,

the wineberry,

and the vine that will eventually claim all of Princeton, porcelainberry.

Gone are the butterfly-attracting flowers, as Turning Basin has returned to the default landscape of mowed grass, trees, and whatever. Shall we fault the planters of this garden who didn't follow up? Kids grow up and girlscout troops come and go. Maybe fault the lack of government budget for anything beyond unskilled, custodial maintenance of our public landscapes? Let's just say that love moved on.