Journal archives for March 2020

March 08, 2020

March Manhattan butterflies

After a historically warm winter, butterflies are already on the wing in New York, with recent reports of Mourning Cloak, Eastern Comma, and Cabbage White in the city. Mourning Cloaks and Eastern Commas overwinter as adults (so do Question Marks) and emerge on warm days; Cabbage White overwinters in pupal form. American Lady is also possible in March, though whether they are individuals that overwintered or migrated from the south is apparently unclear.

Remarkably, an American Snout was photographed in Prospect Park, Brooklyn, on March 2:

Keep your eyes peeled for early sightings of these species, especially as temperatures reach 50s and 60s in the city over the next few days.

And watch for any Celastrina azures -- so far, there are no iNaturalist records of this complex in March in Manhattan. If you come across one, try to get photographs showing as much detail of the wings as possible.

Here's @kasimac's photo of an Eastern Comma from Central Park on March 4, when temperatures hit 57 degrees:

Manhattan butterfly project is here, and checklist-in-progress is here:

@kasimac @kenchaya @nycnatureobserver @nycbirder @pawelp @susanhewitt @spritelink

Posted on March 08, 2020 02:53 AM by djringer djringer | 4 comments | Leave a comment

March 19, 2020

Celastrina Azures in Manhattan: What Do We Know?

This lovely shot by @ansel_oommen depicts a Summer Azure (Celastrina neglecta) during July in Central Park, with a characteristically pale, whitish underside; small, fine dark markings; no strong marginal markings on the hindwing; and a white, unmarked fringe on the hindwing.


Celastrina is a genus of small gossamer-winged butterflies (family Lycaenidae) with species distributed across North America, the Palearctic, and tropical Asia through Wallacea to New Guinea. In North America, Celastrina species are generally called azures.

Eastern North America holds quite a complex tapestry of similar-looking azure species. These species differ in timing of flights, number of broods, and host plant choices, and locality matters a lot -- what's true in one place may not be in another. Flight dates, number of broods, and host plant choice can all vary across a species’ range, and appearance can vary seasonally, all greatly complicating identification. This recent paper from @bryanpfeiffer summarizes several of the issues with this group:

What About Manhattan?

Several Celastrina azure species fly within 50 miles of Central Park, but which azures occur specifically in Manhattan's urban parks and small islands? It currently appears that only the Summer Azure (Celastrina neglecta) occurs in New York County, flying from late May to mid-October. The species’ peak abundance appears to occur in June and July, and it appears to utilize a variety of host plants in Manhattan.

How do we arrive at this hypothesis?

First, here are the currently accepted species (following Pelham 2020 with iNaturalist’s common names) that occur in the tri-state area (NY-CT-NJ), arranged in rough order of flight times at our latitude and with a few notes relevant to our region:

  • Celastrina lucia (Lucia Azure). Flight: March-April, and possibly later. Broods: 1-2+. Range: High latitudes and elevations across North America, nearing southern limit of its range in the greater NYC area. Appearance: Often dark grayish below and heavily marked, but variable. Notes: Recently shown to have both spring and summer flights in southern Ontario:
  • Celastrina ladon (Spring Azure). Flight: March-April/early May. Broods: 1. Range: Widespread in eastern U.S. but range not fully understood. Appearance: Often lighter than C. lucia but with somewhat dark ventral hindwing margin. Crucially, males have a distinctive dorsal wing scale morphology visible under magnification. Notes: See notes on distribution, wing scales, and introgression with C. lucia and C. neglecta which can cause males of those two species to show the distinctive C. ladon male wing scale morphology here:
  • Celastrina idella (Holly Azure). Flight: Spring. Notes: Occurs south of NYC, from central New Jersey along the Atlantic Coastal plain, utilizing native hollies as host plants. Described in 1999:
  • Celastrina serotina (Cherry Gall Azure). Flight: May-June. Broods: 1. Range: Northeastern U.S. Appearance: Whitish below often with fairly bold dark markings and fairly white hindwing fringe. Notes: Uses mite galls on native Prunus cherry leaves as larval food (, but will use other host plants too (and C. lucia larva recently shown also to use cherry galls in paper linked above). Described in 2005:
  • Celastrina neglecta (Summer Azure). Flight: late May-October. Broods: Multiple. Range: Widespread east of the Great Plains. Appearance: Whitish underside with reduced markings and white hindwing fringe. Notes: Uses a variety of host plants and has multiple broods annually.
  • Celastrina neglectamajor (Appalachian Azure). Flight: Overlaps with C. neglecta. Broods: 1. Range: Appalachian Mountains and nearby areas where its host plant grows. Appearance: Very similar to C. neglecta. Notes: Only one host plant: Actaea racemosa (Black Cohosh).

When we examine iNaturalist reports for Celastrina azures in New York County, New York (and iNaturalist provides by far the most abundant publicly available data on this question), we see that there are currently zero Celastrina records in Manhattan in March or April. In fact, the first report across any year is not until May 23. This is particularly noteworthy because the City Nature Challenge in late April results in a large number of observations submitted to iNaturalist, relative to other months. As of March 2020, there are approximately 23,400 iNaturalist observations of all taxa in April (all years combined) vs. 14,500 in May and 12,700 in June. However, there are zero Celastrina observations in April, a handful in May, and nearly 30 in June. If azures were regularly flying by late April in Manhattan, it seems likely that someone would have reported one. After a sporadic showing in late May, azures peak in Manhattan in June and July and taper off through August, September, and into October, according to iNaturalist reports.

The absence of March, April, or early to mid-May azure reports argues strongly that neither C. lucia nor C. ladon have populations in Manhattan. Even if C. lucia has a second, summer-flying brood in our broader region, there is no evidence of a spring brood in Manhattan, so there would be no summer brood.

The late-May start date for our azure flight (and the visual appearance of those May individuals, with very light markings on their ventral hindwings) also seems likely to rule out C. serotina, though more careful observation might be worthwhile. Late May is when the first C. neglecta would be expected to emerge, and C. neglecta is known to have multiple broods through the summer, which tracks the distribution curve present in iNaturalist data so far.

What of C. neglectamajor? The Appalachian Azure is very similar to the Summer Azure, but it uses only one host plant: Actaea racemosa (Black Cohosh), at a specific stage of flower bud development. There are likely no wild stands of the plant in Manhattan, and though it is cultivated in Central Park and probably other parks, its presence there is strongly isolated from native stands, probably making a population of this specialist butterfly unlikely. (Note that Summer Azure will also use Black Cohosh as a host plant:!searchin/nyleps/appalachian$20azure%7Csort:date/nyleps/oOFQyzKGDy4/nerW9rrEBQAJ)

It is not clear exactly why C. lucia, C. ladon, and C. serotina should not occur in Manhattan. Some of their host plants grow prolifically in our parks and between the cracks of civilization. Perhaps habitat fragmentation or urban pressures are too intense for them. Or perhaps we need to pay more attention.

Harry Pavulaan is one of the people who has contributed most to our understanding of azure ecology and taxonomy in the last 30 years (describing, with David Wright, both C. idella and C. serotina). So, I asked him this month what he knew about azure distribution in Manhattan. Citing New York City Butterfly Club data, he agreed that C. neglecta is likely our only azure.

Further Research: How You Can Help

Is this the last word on Celastrina in Manhattan? I hope not! If there's one thing we know about Celastrina azures, it's that they're full of secrets and surprises. They reward careful and patient observation.

Other azure species do occasionally turn up in NYC's outer boroughs. For example @cesarcastillo photographed this individual in mid-March in Alley Park, Queens, a couple of years ago: A similar-looking individual was photographed at Wave Hill in The Bronx last week: And @christophereliot photographed this very dark individual in Prospect Park, Brooklyn, on May 1 two years ago:

Could there be other azures showing up around the edges of Manhattan, at Inwood Hill Park, or on Randalls or Governors islands? Maybe, and now is the time to start looking, as we officially mark the arrival of spring after a historically mild winter.

If you did find an early azure, and it were a male, high-magnification photographs of the upper wing surface showing the details of the scales would be extremely useful.

Connecting azures to host plants in Manhattan would be another useful line of exploration. Right now, iNaturalist has two records of female Summer Azures ovipositing on flower buds: this one from @kasimac (on Salvia) and this one from @filiperibeiro, apparently on some sort of shrubby Cornus -- can anyone ID that plant?

If you can catch azures ovipositing (or in their tiny, obscure larval form) and document the plant, that could be very interesting information. And as May and June unfold, keep an eye on cherry leaf galls and young Black Cohosh flower spikes if you want to be the first to document C. serotina or C. neglectamajor in Manhattan. Are they here and just overlooked? Or do they truly not occur in an area of such human density? Right now, all we know for sure is that they haven't been documented yet.

Two general reminders: Butterflies of Manhattan project is here:, and checklist-in-progress with monthly abundance graphs is here:

Joyous Vernal Equinox, and thanks to Harry Pavulaan and all of you who contribute your observations and expertise. Be healthy and well.

Tagging some of you who contribute a lot of butterfly observations and/or IDs in New York as an FYI: @blkvulture @cathyweiner @craghorne @danielatha @greengenes @kdstutzman @kenchaya @klodonnell @maractwin @nlblock @nycbirder @nycnatureobserver @pawelp @sadawolk @spritelink @steven-cyclist @susanhewitt @wayne_fidler @zahnerphoto

Posted on March 19, 2020 01:04 PM by djringer djringer | 6 comments | Leave a comment

March 27, 2020

Stuck inside? ID some NYC butterflies!

We should all be staying at home and away from other people to limit the spread of COVID-19. So if you have a few minutes this evening, why not get a little nature fix by identifying some NYC butterflies?

Here are the New York County butterfly observations that still need ID confirmation (and I've broken out various groups in more detail below): (note: You can tick the "reviewed" checkbox to the right of the filter bar if you want to revisit observations you'd already seen in the past). Don't follow the herd, of course -- make the IDs in which you are personally confident.

For reference, here's the work-in-progress Manhattan Butterfly List (using a lot of Research Grade data from iNaturalist):

Some groups to explore for those of you who specialize:

Below: a female sulphur butterfly that I observed last summer in Hudson River Park. I think she is a white form Clouded Sulphur (Colias philodice) based on the narrow black border on the dorsal hindwing that does not fully enclose pale spots, and only small spots in the dark forewing margin, but she is one of many butterfly observations in the city that still lacks ID confirmation.

Tagging some top identifiers -- thanks for all you do! @nycbirder @wayne_fidler @nlblock @greengenes @kdstutzman @sadawolk @maractwin @susanhewitt

Posted on March 27, 2020 12:16 AM by djringer djringer | 1 comment | Leave a comment

March 29, 2020

Identifying the Violets of Manhattan (New York County)

With March drawing to a close, a tiny violet caught my attention in a concrete Hudson River Park flower bed. I didn't recognize it, which reminded me that I'd been meaning to learn more about the violets of Manhattan. I've always loved violets -- they're so familiar, and yet challenging. (And they can be very surprising.)

You can read about New York City's violets in @danielatha's 2018 State of New York City's Plants, but Manhattan doesn't have the wetlands, forests, and beaches of the outer boroughs. Which species thrive, or at least hang on, here in this densest borough?

After analyzing about 1,000 observations in iNaturalist, I've written up 10 species below (one is a twofer). This seems to capture the reported diversity on iNaturalist to date, not counting a couple of isolated cultivated species. There may be more diversity than is reported so far, and I probably haven't got everything quite right, so please weigh in with your comments.

As you observe violets this season, please try to photograph four things:

  1. A front view of the flowers, on their own level (an overhead shot has less ID value);
  2. A profile view of the flowers, to show sepals, spur, and stem;
  3. A closeup of a leaf or two;
  4. The overall habit of the plant (basal leaves only? stem leaves?) with a size reference.

All photos in this post are clickable -- the links will take you to the original observations. Thanks to the photographers for making their pictures available with a Creative Commons license.

Oh, and that violet I found the other day is #3 below.

1. Common Blue Violet (Viola sororia)

Common Blue Violet is an extremely successful and abundant native violet in Manhattan, growing jubilantly in lawns, parks, beds, borders, and between cobblestones and in pavement cracks. It blooms profusely in April and early May. It is the default purple violet anywhere in the borough. It can form dense, thick carpets, and while it may be small in mowed or thin-soiled areas, it can grow several inches tall in favorable locations.

Flowers rise individually from the rhizomes; they are not on arranged on stems with leaves. Leaves are coarse and broad, heart-shaped with a pointed tip and sharp teeth on the margin; they ascend from creeping rhizomes. The purple form has rich, vibrant purple flowers with a touch of bright blue at the base of the petals. There are long, dense hairs on the inside of the two lateral petals, tending to visually obscure the reproductive organs inside the flower. The spur is quite short and blunt, barely protruding behind the flower.

(Update 04/02/2020): The color of the Common Blue Violet is quite variable. Some plants produce flowers with more reddish or pinkish hues, like this gorgeous plum-colored individual below. Note too, as shown in this image, that the first leaves to emerge in spring are blunt-tipped with rounded teeth, and are rather smooth, in contrast to coarser, more angular leaves produced as the season unfolds.

Confederate Violet, or V. s. forma priceana, is a variation of Common Blue Violet with striking white, purple-centered flowers. In all other respects, it resembles the blue form. It is also abundant in the city, and it is frequently misidentified as many other species from all over the world.

2. Eurasian Sweet Violet (Viola odorata )

The introduced Eurasian Sweet Violet is very fragrant -- the quintessential violet scent -- which is a good clue to its identity. Working from photographs can be a bit harder, particularly since most people shoot violets from above. The leaves, which are kidney-shaped with scalloped margins, form a basal rosette; the flowers grow individually from the base of the plant. The flowers are purple, or sometimes white or pink, and have minimal hair on the lateral petals so that the reproductive organs are clearly visible (unlike V. sororia in which the hairs are much longer):

This species is said to be naturalized in New York. However, having gone through all the records in iNaturalist, I can't find a lot of evidence for it. Most plants are either clearly V. sororia or are ambiguous at best (especially since the first leaves of V. sororia early in the season can appear smaller and more rounded, more like those of V. odorata).

This beautiful pink-flowered plant below, posted by @aberkov does indeed appear to be V. odorata (again, most V. odorata flowers are purple); it's not clear whether it's wild or cultivated. (Update 03/29/20: aberkov confirmed that the plant pictured below is cultivated. I now believe that V. odorata is extirpated in our region, except where reintroduced in cultivation. Here's a map of Research Grade observations in the Northeast -- the species is effectively absent away from western New York and southern Ontario, which is amazing: What accounts for this I wonder?)

3. European Dog Violet (Viola riviniana Purpurem Group)

The European Dog Violet has a purple-leaved form that is used in the horticultural trade and is sometimes sold as V. labradorica, which is an incorrect name for this plant because V. labradorica is a different violet native to northeastern North America.

Apparently this plant can self-seed and become weedy under some conditions. There is some evidence from iNaturalist observations that it occurs in and around cultivated areas in Manhattan (, though it is not listed as an established species in NYBG's 2018 State of the City's Plants report. This is a small plant with purple-tinged, somewhat fleshy-looking foliage, leaves on the flower stalk, pointed sepals, and slender, violet-purple blooms with long spurs and only short hairs in the flower's throat, revealing the round-tipped style.

See discussion of this plant here: and here:

4. Bird's Foot Violet (Viola pedata)

I believe the few observations of the rare and beautiful Bird's Foot Violet in Manhattan are plants growing in native plant gardens: The flower and leaf shape together are distinctive.

5. Downy Yellow Violet (Viola pubescens)

Aptly named, the Downy Yellow Violet bears bright yellow flowers on hairy stems. The plant sends up a long stem, and flowers grow from the leaf axils along the stem. Basal leaves are usually absent.

This species is loosely cultivated in Central Park and a few other parks in Manhattan; it's used in restoration plantings and can be found in the Ramble and Hallett Nature Sanctuary. It's been cultivated in the park since at least 1865, but appears to depend on human intervention for survival in this heavily altered landscape. It seems that iNatters have different opinions on whether this and the following two species should be marked "cultivated" or "wild." Here's a photo shot from @lisabrundage:

6. Canada Violet (Viola canadensis)

The tall and striking Canada Violet, like Downy Yellow Violet above, depends on human intervention to thrive in Central Park, but thrive it seems to do. Because the species appears to spread on its own in areas where it has been planted, some iNatters believe it should be considered wild for the purposes of iNaturalist. This is a leggy plant, with leaves and flowers sprouting off the stem. Flowers are white with a yellow center and purple backs on the top two petals, setting this species apart from the following species. Here's a nice shot from @ansel_oommen:

7. Cream Violet (Viola striata)

Cream Violet is another restoration species in Central Park, present because people brought it there in the last few decades to restore wooded areas. It could be confused with Canada Violet (above), but it lacks yellow color in the mouth of the flower and the back of the petals is all white.

8. European Field Pansy (Viola arvensis)

The small, pale European Field Pansy is, as its name suggests, introduced from Europe. It typically has flowers a half-inch or so in size that are cream-colored with some yellow on the bottom petal and a few guide marks for pollinators. Its sepals tend to be longer than its petals, making the flower look partially enclosed ( Some individual plants can look intermediate between this and V. tricolor, which is described next (I'm pondering these, for example:

There is an American field pansy species, V. bicolor, but it differs in appearance ( and apparently has not been recorded from Manhattan.

Here's a V. arvensis example from @jholmes; note the long sepals and bicolored flower:

9. Wild Pansy (Viola tricolor)

Wild Pansy, also known as Johnny-Jump-Up and Heartsease, is a Eurasian plant that has been introduced into North America. It appears to be uncommon around Manhattan. It is also an ancestor of many cultivated pansy plants as you can see in the section below, and those should be identified appropriately in iNaturalist. Naturalized V. tricolor generally show tricolored purple, white, and yellow flowers with purple rays. They tend to be larger and more colorful than the previous species, with sepals that are not longer than the petals ( This is naturally a very variable species, and I also wonder whether some of these plants are coming from self-seeding ornamentals that slowly revert to a more ancestral form (e.g., this observation of @susanhewitt's

Here's a photo from me:

10. Garden Pansies (Viola wittrockiana) and "Violas"

Is there anything as cheerful as the big, colorful, ruffled face of a Garden Pansy? These large-flowered garden plants are horticultural hybrids going back hundreds of years. They have been bred in colors from white to nearly black, with a wide range of colors in between, and they often have a dark blotch in the middle of a lighter-colored flower, such as burgundy on yellow.

Garden Pansies are a very common sight during cooler months in Manhattan in pots, window boxes, and planters; around street trees; and in flower beds. They should be marked "cultivated" in iNaturalist; they do not naturalize. See discussion about their taxonomic history under a recent taxonomic swap: Here's a recent observation from @susanhewitt:

But not all pansy-like ornamentals that you encounter in Manhattan are true Viola wittrockiana. A range of smaller, sometimes striped, and variously colored plants commercially known as "violas" are prevalent as well. They often take over in summer after Garden Pansies fade. These ornamental plants are derived from European V. cornuta and V. tricolor (see and section B2).

I would suggest that we identify them on iNaturalist as Melanium, which is the pansy section of the genus Viola, and they should be marked as cultivated. Here's an example from @olibr_:

That's all for now. I'll probably update this post periodically as we learn more. Let me know what you think, and if you want to try your hand at IDing some violets, click here:

Tagging some more of you that I think will be interested: @srall @elevine @sadawolk @mertensia @oxalismtp @tsn @zihaowang @klodonnell @wayne_fidler @elizajsyh @nycnatureobserver @craghorne @spritelink @irag @andrew_garn @kai_schablewski @ballardh

Posted on March 29, 2020 11:25 AM by djringer djringer | 1 observation | 9 comments | Leave a comment

Identifying spiny orbweaver (Gasteracantha) egg cases

An oblong silken structure with bright green threads, attached to a leaf, a wall, or even a car window. What is this? You've probably found the egg case of a spinybacked orbweaver. Here's an example:

An egg case of spinybacked orbweaver (Gasteracantha cancriformis), showing the characteristic lengthwise stripe of emerald green and neon green threads. Photographed by @casseljs in Georgia, USA.

In the southern United States, and throughout most of Latin America and the Caribbean, the colorful spinybacked orbweaver (Gasteracantha cancriformis) builds egg cases like this, often near or even upon human habitation. The female of species does not put her egg case in its web like certain other orbweavers; instead, she seeks out a leaf or -- for whatever reason -- hard human surfaces (here's one on a handrail for swimming pool steps:

Here's a description of the process from the University of Florida: "After the eggs are laid on a white silken sheet, they are first covered with a loose, tangled mass of fine white or yellowish silk, then several strands of dark green silk are laid along the longitudinal axis of the egg mass, followed by a net-like canopy of coarse green and yellow threads."

Clear enough. But what if you find a similar structure without the central green stripe?

Well, orbweavers from several other genera make similar egg cases; for example:

-- Neoscona: and;
-- Eriophora:;
-- Araneus:

I think this argues for caution when identifying egg cases that lack the emerald green longitudinal stripe, especially if these cases are white or yellow without any green color. Those could belong to another orbweaver species. Some egg cases are green but do not have a distinct central stripe -- those get identified as Gasteracantha cancriformis pretty frequently (example: Is Gasteracantha the only orbweaver that produces green silk in the Americas? I'm not sure, but that appears to be the conventional wisdom.

In Hawaii, the situation is unclear because both Gasteracantha cancriformis and Thelacantha brevispina have been introduced onto the islands ( Thelacantha is related to Gasteracantha, and I'm not sure how to distinguish the egg cases of the two species. Here are the current examples in iNaturalist (and I won't put much stock in the IDs, which seem to be made without much evidence): Perhaps those of you in Hawaii or within the native range of Thelacantha know how to tell the difference?

Similar egg cases are recorded in Asia, where multiple Gasteracantha species (plus Thelacantha and related genera) live in sympatry. I have no idea how to identify these to species; perhaps some of you who live there do know. Here's an example from @wallacechen in Taiwan:

How can you help advance our knowledge on these questions? Here are some ideas:

  • If you live in a place with one or more of these species, document what's happening in as much detail as you can and submit your observations to iNaturalist.
  • If you come across an observation like this on iNaturalist, please identify it as best you can and mark Life Stage: Egg in the observation annotations section so that it can be more easily found in the future. Feel free to tag someone for help, too.
  • If you have additional information from papers, field guides, or other sources, please post a comment below!

Tagging a few of you who may want to bookmark this to link in your future IDs: @jgw_atx @joemdo @chuuuuung @wildcarrot @botanicaltreasures @lisa_bennett @claggy @tiwane @michelotto @tigerbb

Posted on March 29, 2020 10:19 PM by djringer djringer | 8 comments | Leave a comment


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