Insect Year in Review 2021

Observing the diversity of life that coexists in one place is one of the rewards of visiting the same natural area over a long period of time. My garden not only offers myself and passersby such an observatory. It’s also a laboratory in which I can research how insects engage with their environment – both biotic and abiotic – and imagine, design, and create habitat to better provide for their needs.

The Front Garden, November 2021

I use iNaturalist to document the diversity of life in my garden. Although I only posted my first iNaturalist Observation in 2017, my garden Observations now span more than a decade. As of this year, I’ve documented over 400 insect species making use of my garden.

iNaturalist Observations · Flatbush Gardener - Top 25 Species - 2021-12-31

This biodiversity, and my documentation of it, is intentional. And although all of this is by design, all I can do is uncover the latent urban biodiversity in and around my garden. Each new species I find is a surprise to me.

Native Plants

As I explained in last year’s Home of the Wild, native plants have been a significant focus of my gardening since we bought our home and I started the current garden in 2005. I’m always researching and experimenting with new species. And, like any avid gardener, I’m always killing things off, too.

I do my best to track my acquisitions, and failed plantings, in a spreadsheet. I categorize the species by whether they are native to the five counties of New York City, native to the NYC region – e.g.: within two counties – or are some other species native to eastern North America.

This chart summarizes the increase in native plant diversity in my garden over the years. Stacked columns, plotted against the left axis, show the number of species I acquired each year: blue for NYC-native, red for NYC-regional, and green for eastern U.S. native plant species. The large undated bar on the left represents plants I brought with me from prior gardens, or for which I’ve lost track of when or how I got them. The lines, ploted against the right axis, show the total number of species: blue for NYC-native plant species, and green for everything else.

Native Plants in my Garden by Year - 2021-12-31

2014 stands out as an exceptional year for plant acquisitions. That was my first year visiting the Native Plants in the Landscape Conference in Millserville, Pennsylvania. It has an enormous accompanying native plant sale with vendors from all over the mid-Atlantic, of which I took full advantage.

I maintain a Wish List of plants I want to try to grow in my garden. (Anyone know of a NYC-regional source for dwarf prairie willow, Salix occidentalis?!) The past few years I have targeted species for their ecological value in my garden:

  • Fill in plant families that are missing, or under-represented, in my garden, such as Apiaceae, e.g.: Zizia aurea.
  • Extend the flowering season, especially early in the year when native plant blooms are scarce. For example: Packera is the earliest-blooming Asteraceae I’ve found, so I’m trying to establish that in my garden.
  • Grow more plants to support specialist flower visitors, such as bees.

As of this year, I’m growing nearly 300 species of native plants, over 200 of which are native to New York City. With that increase in plant diversity, there’s been an increase in insect diversity (though habitat needs more than having the right plants).

Insect Species

Most of the insects that have visited my garden over the past decade fall into one of six groups:

  1. Diptera, flies: 103 species
  2. Wasps. i.e.: other Hymenoptera, excluding bees and ants: 70 species
  3. Coleoptera, beetles: 57 species
  4. Epifamily Anthophila, bees: 55 species
  5. Lepidoptera, butterflies, moths, and skippers: 55 species
  6. Hemiptera, bugs: 43 species

That’s where things stand today. But this didn’t happen all at once. This chart shows how I’ve accumulated species records in my garden for each of these groups over time. We can see that the slope of the lines increased sharply over the past three years, from 2019 through 2021.

Insects in my Garden - Cumulative Species at the end of each Year by Taxonomic Group - 2021-12-31

It’s a little easier to see which taxa contributed most to the increases if we look instead at just the new species, instead of the total number of species. This stacked column chart shows the number of new species I’ve found each year in my garden, for each of my six focus taxa. Again, the last three years stand out as being responsible for most of the increase.

Insects in my Garden - New Species each Year by Taxonomic Group - 2021-12-31

The color codes of the stacked column segments are the same as the lines in the previous chart to make it easier to draw comparisons between the two:

  1. I’ve seen most of the fly species in just the past two years.
  2. It’s the same for the wasp species.
  3. Beetles saw a spike in new species observed in 2017 and again in 2020. Otherwise, a fairly steady uncovering of new species each year.
  4. Bees have seen a remarkably steady discovery of new species over the years. The first few years found lots of new species. More recent years not so much. 
  5. Butterflies, moths, and skippers have also shown up mostly over the past three years.
  6. Most of the bug species were found during the three year span from 2018-2020. Not so much this past year.

I believe that at least some of these increases reflect success in creating habitat for diverse insect species. But my observing behaviors have not been consistent over the years. Am I seeing more species just because I’m spending more time looking for them? And — if so — how much observation do I need to do to be confident I’m adequately sampling my garden?

Insect Observations

I ramped up my Observations the past two years – 2020 & 2021 – to increase my contributions to two iNaturalist Projects:

As mentioned above, I wrote about the first Project, and the history of my garden as insect habitat on my blog last year. ESNPS was originally scheduled to run only three years, from 2018 through 2020. Of course, the pandemic changed those plans; they decided to extend the iNaturalist portion another year, into 2021.

By concentrating on these two efforts, I increased my Observations in my own garden by a factor of 8. This year, I also invested in better macro equipment. So I was spending a lot more time in my garden, and was able to capture many more individuals with photographs good enough for identification.

Insects in my Garden - Observations per Year by Taxonomic Group - Chart

The Empire State Native Pollinator Survey includes bees and Syrphidae, flower and hover flies, among its focal taxa. Although my increased observation found more of everything, bees and flies took up a greater proportion of the total observations.

How many observations do I need to make to have high confidence I have found most of the species present in my garden? This chart compares the number of species observed against the number of observations for the four most diverse taxa: flies, wasps, bees, and beetles. I’ve added labels for the two most recent years, to highlight that not only did they have the most observations, they are also the years I found the most species.

Insects in my Garden - Number of Species by Number of Observations - Chart

Last year was not a pace of observation I can sustain indefinitely. There’s a lot of effort in taking high-quality, identifiable macro photographs of insects in the garden to uploading them as verifiable observatinos in iNaturalist. Some days it took most of my waking hours, spread over multiple days, just to process all the photographs from a single day of observation.

My iNaturalist activity the past year was artificial, driven by the gamification offered by the two Projects in which I was actively “competing”. But this past year gave me a strong foundation for continuing to make effective observations. I look forward to being surprised by future discoveries in my garden.

Related Content

Hot Sheets Habitat, 2021-11-19
Documenting Insect-Plant Interactions, 2021-10-29
Home of the Wild, 2020-05-13


City Nature Challenge 2018

Viola sororia, common blue violet, in the front yard, April 2018
The “weedy” remnants of my front lawn, where Viola sororia, common blue violet, has taken charge. Easily overlooked, it seeds itself readily without any help from me (or any other gardener). Yet this species is native to New York City. It’s one of my iNaturalist observations from my garden for this year’s City Nature Challenge.

Today, Sunday, April 29th, is day 3 of the global City Nature Challenge, which continues into tomorrow. Building on the explosive popularity of iNaturalist as a platform for observations, this gamified bioblitz pits cities against each other, to see which can identify more taxa of living species in a 96-hour period.

NYC is currently is 6th place globally, and 4th nationally. There are still plenty of opportunities to join special events organized for New York City, with events in 4 of our 5 boroughs today, and more tomorrow.

I wasn’t able to take part in yesterday’s festivities. This weekend, I have to get my garden ready for this season’s garden tours. Armed with only my phone, I kept an eye out for anything I might see, uncover, or unearth. I was rewarded.

I came up with 16 observations yesterday. In addition to Viola sororia introduced at the top of the post, I observed:

And not a vertebrate among them. There were plenty of birds, and the occasional squirrel, in the garden. I wouldn’t have been able to get close enough with my phone to any of them to get a decent photo.

Related Content


An Elegy for Biophilia

I was moved to write this by a short missive from Reverend Billy:

When I go to pray, which is sometimes difficult being so without any god, I think of that time in my life, because the natural world was overwhelming the god that my family insisted was all-powerful and all-knowing. Creation was overwhelming the Creator and it came in the form of undulating prairie grasses.

I was raised in temperate and tropical suburbia. Even in those landscapes, the woods in the backyard, or the palmetto swamp at the end of the road or the canal, drew me to them. They were my expanse. Yet, compared to what existed before the forests were razed and the swamps drained, the landscapes of my childhood were impoverished.

The shifting baseline degrades further. More than half the world now lives in cities, with less ready access to nature than ever before in the history of our species. Biodiversity is an environmental justice issue.

I’ve chosen to live my adult live in a city. Even here, those childhood experiences guide me. I garden because it connects me to nature, it nourishes me. The beauty I invite is not of my making, but larger, deeper, and older than I can comprehend.

I believe it everyone’s right to have that connection for themselves. Not only a right, but necessary. Not only for our own health, but to have some hope for the future health of our planet.

That hope, however impoverished, is what keeps me going.

Gardening with the Lepidoptera

Tomorrow, Sunday, June 12, my garden will be opened for its second tour of the season: the Victorian Flatbush House (and Garden!) Tour, to benefit the Flatbush Development Corporation (FDC). Earlier this week, I wrote about the transformation of the garden over the six past years, since we bought our home. Today, I’m providing details about one part of that transformation, one which is easy to replicate on a small scale, even in a tree bed or on a balcony.

After readying my backyard native plant garden for its debut tour for NYC Wildflower Week in May, I decided to complete the requirements to register my garden as a Certified Wildlife Habitat (#141,173) with the National Wildlife Federation. With over 80 species of native plants, I easily met three of the four requirements: shelter, food, and places to raise young. All I lacked was water, a requirement satisfied by placing some birdbaths and a terra-cotta cistern.

On Friday, May 27, I mounted the plaque on the entrance arbor.
Certified Wildlife Habitat sign

The morning after I put out this welcome mat, I saw butterflies visiting a vine in the garden. I was puzzled, since the plant wasn’t blooming yet. Closer observation revealed that they were laying eggs on the vine.

Battus philenor, Pipevine Swallowtail
Battus philenor, Pipevine Swallowtail, ovipositing on Aristolochia tomentosa, Wooly Dutchman’s Pipevine

At first, I thought they were Papilo troilus, Spicebush Swallowtail, a species I’ve encountered before. But one of my tweeps, Marielle Anzelone, id’d it as Pipevine Swallowtail, a lifer butterfly for me. Upon researching the species, I was somewhat relieved to learn my confusion has some scientific basis: both the Spicebush and Pipevine Swallowtails, along with several other species, are members of a mimicry complex. As described on BugGuide, “members of this complex present a confusing array of blue-and-black butterflies in the summer months in the eastern United States.” The arc of orange spots on the underside of the hindwind, clearly visible in the photo above, is a key to distinguishing this species from other members of the complex.

The other key was the host plant. Of course, Pipevine Swallowtail would lays its eggs on Pipevine, in this case,  Aristolochia tomentosa, Wooly Dutchman’s Pipevine. This plant was a rare find; I’ve never seen it offered again, or elsewhere. A few years ago, I visited Gowanus Nursery – my favored retail source for native plants in Brooklyn, even New York City – and asked if they had any Dutchman’s Pipe. I was hoping for A. macrophylla, a species with huge leaves, and a Victorian gardener’s favorite. They had some Aristolochia, but neither of us could id the species. Adventurous gardener that I am, I took a chance and brought home a quart specimen with a few, thin stems and small leaves. When it eventually bloomed, I was able to id it.
Aristolochia tomentosa, Wooly Dutchman's Pipe

A few years later, the plant is huge, with dense foliage, though the leaves have remained small. It keeps reaching upward several feet, self-supporting its lax stems, and climbing into the cherry tree above it. It serves to screen the composting area from the rest of the garden. I think the mature growth of this plant, rather than the habitat plaque, is what attracted the butterflies to my garden, and select this plant as a host.

Eggs, Battus philenor, Pipevine Swallowtail
Eggs of Battus philenor, Pipevine Swallowtail on Aristolochia tomentosa, Wooly Dutchman’s Pipevine

Where I could find them, the eggs were laid only on the young leaves and petioles of fresh growth. This growth is abundant on the mature plant. The eggs are small, especially compared to the depth of the “hairs” of the plant. I suspect laying the eggs on young growth is critical to successful feeding by the young caterpillars. As they get larger, they can manage the larger, coarser hairs and leaves of more mature growth.
Empty eggs, Battus philenor, Pipevine Swallowtail
Empty eggs of Battus philenor, Pipevine Swallowtail, on Aristolochia tomentosa, Wooly Dutchman’s Pipevine. Leaf removed from the vine and U.S. quarter coin provided for scale.

Just five days later, on June 2, the eggs hatched. Newborn caterpillars!
Eggs and Hatchlings, Battus philenor, Pipevine Swallowtail

One day after they hatched, I found a group of four little caterpillars on the underside of a different, but nearby, leaf. Two days later, the group was down to three, and three days later, only two caterpillars were left on the leaf. The feeding damage visible in the photos is distinctive: other leaves on the vine have showed signs of feeding, or other uses, but nothing like the fine ragged edges left by tiny little mouths. I haven’t caught them in the act of feeding; I wonder if they feed at night, to avoid detection when active, and remain hidden during the day?
Caterpillars, Battus philenor, Pipevine Swallowtail
Caterpillars, +2 Days, Battus philenor, Pipevine Swallowtail
Caterpillars, three days after hatching

I’ve lost track of the caterpillars now. The vine is dense, with layers of foliage, and many twisting stems. I’ll watch for feeding damage to try to locate and photograph some of them again as they get larger. I’ll also look for chrysalises; catching them emerging as butterflies would be fantastic luck.

Aristolochia tomentosa is native to eastern and southern North America.
Map of native range of Aristolochia tomentosa

Battus philenor hosts on all species of the genus, so its range covers most of North America.
Battus philenor, Pipevine Swallowtail, Distribution Map, BAMONA

So, how is any of this “easy to replicate”? While flowers provide food to, and the plants shelter, adult butterflies and moths, a host plant meets three of the four habitat requirements: shelter, food, and a place to raise young. Most native plant species are known to host something. Both Butterflies and Moths of North America (BAMONA) and the international HOSTS Database from the Natural History Museum in London are online resources you can use to discover Lepidoptera-plant host associations.

A single container of a grass or sedge on a balcony can provide habitat. The whole of the cumulative impact of scores, hundreds of such micro-habitats will be greater than the sum. Even in urban settings, we can create opportunities for nature to return and thrive, and by reconnecting with it, we thrive as well.


Related Content

Battus philenor, Pipevine Swallowtail, Flickr photo set
Aristolochia tomentosa, Wooly Dutchman’s Pipevine, Flickr photo set


Battus philenor, Pipevine Swallowtail, BugGuide
Battus philenor, Pipevine Swallowtail, Butterflies and Moths of North America (BAMONA)
Battus philenor host plants, HOSTS: World’s Lepidopteran Hostplants Database

Aristolochia tomentosa Sims, woolly dutchman’s pipe, USDA PLANTS Database (Synonym: Isotrema tomentosa (Sims) Huber)
Isotrema tomentosum (Sims) H. Huber,  NY Flora Association Atlas (Does not list as present, let alone native, in NY)

Brooklyn’s Raccoons in the New York Times

Update 2010.01.03: Removed all links to the old Gowanus Lounge domain, which has since been appropriated by some parasitic commercial site.

Flatbush Raccoon, June 26, 2008
Flatbush Raccoon

Last week, I was interviewed by reporter Ann Farmer for the New York Times about my experiences with raccoons. The article is published in today’s Times:

Raccoons have long been widespread in New York City, and there is no way to say with any statistical certainty whether there are more now. But Capt. Richard Simon of the Urban Park Rangers, which is part of the city’s Parks Department, said a rise in the number of 311 callers reporting sightings, encounters or interactions suggests that “the citywide population of raccoons has increased.”

One thing seems clear. In the leafy neighborhoods surrounding Brooklyn’s Prospect Park and Green-Wood Cemetery, residents have been flooding the Internet with raccoon stories.
The City’s Latest Real Estate Fight: Humans Against Raccoons, Ann Farmer, New York Times, July 8, 2008

That pesky Internet! Ms. Farmer cites the Brooklyn blogosphere as one source for the reports:

Chris Kreussling, a computer programmer who lives just south of Prospect Park in Flatbush, posted pictures on his Flatbush Gardener blog recently of several raccoons in his backyard. It elicited a quick round of similar testimonies.

Another Brooklyn blog, the Gowanus Lounge, chronicled multiple raccoon sightings in recent days (link defunct) in Park Slope, Carroll Gardens, Windsor Terrace and Red Hook.

When contacted, many bloggers recalled raccoons rooting around in gardens and compost piles, traipsing into children’s wading pools and sometimes rearing up on their hind legs when startled. Many expressed awe at seeing the nocturnal mammals so close.

“People need access to wildlife in urban areas,” Mr. Kreussling said. “I consider it a bonus.”

That last quote is a reference to biophilia, literally “love of life or living systems.” I think the way I expressed it in the interview was something like: People need nature around them.

Ms. Farmer also interviewed several of my neighbors. Check out Nelson Ryland’s cautionary tale of the hazards of cat doors!

Thanks to my neighbor Brenda of Crazy Stable and Prospect: A Year in the Park for putting Ms. Farmer on the trail!

Related Posts

Rabies in NYC: Facts and Figures
Summer Nights, June 26, 2008


The City’s Latest Real Estate Fight: Humans Against Raccoons, Ann Farmer, New York Times, July 8, 2008

Exploring Biophilia Through a USB Microscope

Tiny Strawberry. Credit: Michaela and Cassandra.

I’m in North Carolina this week, visiting my parents with my sister and nieces. It’s a confusing time, with both my nieces and parents demanding both my sister’s and my attention. “Which imaginary friend do you want to help me feed?” “Did I show you this?” So I welcome activities which can engage everyone, including me.

For this visit, my father bought an inexpensive USB microscope. I’ve been thinking about getting one of these myself, so I welcomed the opportunity to play around with one. It also turned an otherwise ordinary trip through the backyard with the nieces into an expedition. We collected samples – “specimens” – along the way, for examination under the microscope. Here are some of the highlights.

Moss and Lichen from a decaying stump. Credit: Xris.

Jewelweed (Impatiens capensis). Credit: Michaela and Cassandra.

Tip of a fern frond (unidentified). Credit: Xris

Diseased Leaf, Credit: Michaela and Cassandra.

Another Diseased Leaf. Credit: Michaela and Cassandra.

Nurtured by our parents, Both my sister and I have a life-long love of nature, and she has clearly nurtured the same in her children. My nieces picked out all these samples. They identified, and I gathered many of the specimens (there was poison ivy about). In a half-hour expedition, we collected about 20 samples, most of which went under the microscope. Much of that half-hour was taken up by observing the wildlife: electric blue damselflies, swallowtail butterflies, a frog, fish, a cardinal, and a rabbit. My nieces each carried their own binoculars. They’re 7 and 8 years old.

All the images are snapshots at 10X magnification. This microscope also offers 60X and 200X, but the controls are mushy and it’s difficult to hold an image in the narrow field of focus. The software is intuitive; my nieces figured out the controls before I did! My nieces did most of the manipulation of framing and lighting for the images above. I’ve credited the photos accordingly above. It took me some exploration to figure out how to capture an image and export it to a JPEG for upload. I did some tweaks for image capture, and some post-processing for shadows and contrast.

They’re brilliant, sometimes scary-smart, children. It’s a privilege to share and explore the world with them.