July 10, 2019

Insect and mite plant pests in NYC -- an early draft

NOTE: this is currently a very early draft and very incomplete!

I decided to start putting together a journal post about the plant-pest species of arthropod that I have observed in NYC. These are mostly insects, but also mites. It will take me a long time to compile the list, as there is no project that covers this. Also the list could potentially become so long as to be unmanageable!

The list will *not* include all the various leafminer species I have found -- those I have already listed in a separate journal post. However, on the rare occasions when I have managed to photograph the adult of a leafminer insect, that will be included here. The list will also *not* include the numerous gall-making creatures, as I want to make a separate post about them.

Rose Slug Sawfly

Carolina Sphinx Moth
Cabbage White
Fall Webworm Moth
Diamondback Moth
Hawaiian Beet Webworm Moth
Squashvine Borer Moth
Cabbage Webworm Moth

Elm Leaf Beetle
Groundsel Tree Leaf Beetle
Red Lily Leaf Beetle
Japanese Beetle
Oriental Beetle
Spotted Cucumber Beetle
Green June Beetle
Goldenrod Leafminer Beetle

Chrysanthemum Lace Bug
Oak Lace Bug
Azalea Lace Bug

...Plant Bugs:
Norvellina chenopodi

Box Sucker
Hackberry Nipplegall Psyllid

Oleander aphid
Mealy Plum Aphid
Cowpea Aphid
Potato Aphid
Black Bean Aphid

...White Flies

...Scale Insects:
Cottony Camellia Scale
Cottony Maple Leaf Scale
Ceroplastes floridensis
Euonymus Scale
Yew Scale


Boxwood Mite

Posted on July 10, 2019 13:27 by susanhewitt susanhewitt | 2 comments | Leave a comment

June 26, 2019

Which leafminer species have I seen in NYC?

To quote the Wikipedia article on leaf miners, "A leaf miner is any one of a large number of species of insects in which the larval stage lives in, and eats, the leaf tissue of plants."

If you are not yet familiar with leafmines, but are curious to see some, start looking carefully for white squiggly lines or whitish blotches on leaves of all various kinds of plants, both wild and cultivated.

On this page I am compiling a list of the leaf miner species that I have observed in NYC. The species identifications are almost entirely thanks to the generosity and brilliant ID-ing work of leafminer expert Charley Eiseman, @ceiseman.

Just a reminder here that leaf mining is an ecological niche, not a taxon. All leaf mines are created by insect larvae, but as Charley points out: "In North America [leafminers] include at least 40 families of moths, 10 families of flies, 6 families of beetles, and 2 families of sawflies." It's also worth saying here that despite the common name, sawflies are not flies; instead they are related to wasps.

Most of the leafminers on this list are larvae of small flies, but so far I have observed several that are moths (microlepidoptera), one which is a chrysomelid beetle, and one which is a sawfly.

Orache Leafminer (on Lambs Quarters) -- Chrysoesthis sexgutella -- moth
..no common name (on Asteraceae) -- Liriomyza eupatorii -- fly
Cabbage Leafminer (on Garlic Mustard) -- Liriomyza brassicae -- fly
..no common name (on Asteraceae) -- Liriomyza eupatorii -- fly
Mallow Leafminer (on mallow family) -- Calycomyza malvae -- fly
Burdock Leaf Miner (on burdocks) -- Liriomyza arctii -- fly
Columbine Leafminer (on garden columbines) -- Phytomyza aquilegivora -- fly
..no common name (on White Clover) -- Liriomyza fricki -- fly
..no common name (on Elm leaves) -- Agromyza aristata -- fly
..no common name (on White Snakeroot) -- Calycomyza eupatoriphaga -- fly
Elm Leafminer (on elms) -- Fenusa ulmi -- sawfly
..no common name (on elms) -- Agromyza aristata -- fly
..no common name (on Seaside Goldenrod) -- Nemorimyza posticata -- fly
..no common name (on Asteraceae) -- Calycomyza promissa -- fly
Goldenrod Leaf Miner (on Seaside Goldenrod) -- Microrhopala vittata -- beetle
Morning-glory Leafminer (on Convolulaceae) -- Bedellia somnulentella -- moth
..no common name (on Chenopodiaceae) -- Chrysoesthia lingulacella -- moth
Milkweed Leafminer (on Common Milkweed) -- Liriomyza asclepiadis -- fly
Leaf Miner on Tulip Tree (on Tulip Tree) -- Phyllocnistis liriodendronella -- moth
..no common name (on goldenrods) -- Calycomyza solidaginis -- fly
..no common name (on garden columbines) -- Phytomyza aquilegiana -- fly
..no common name (on Amaranthus blitum) -- Pegomya wygodzinskyi
Poison Ivy Leaf-miner (on Poison Ivy) -- Cameraria guttifinitella -- moth
Grass Sheathminer (on a weed grass) -- Cerodontha dorsalis -- fly
..no common name (on buttercup) -- Phytomyza ranunculi -- fly
..no common name (on Bull Thistle ) -- Scrobipalpa acuminatella -- moth
??Brassica Leaf Miner (on radish) -- Scaptomyza flava -- fly
Locust Digitate Leafminer Moth (on Black Locust) -- Parectopa robinella) -- moth
Chrysanthemum Leafminer (on Asteraceae) -- Phytomyza syngenesiae -- fly
..no common name (on Eastern Cottonwood) -- Stigmella populetorum -- moth
??no common name (on a Rumex species) -- Pegomya bicolor -- fly
..no common name (on Groundsel Tree) -- Bucculatrix ivella -- moth
..no common name (on elm) -- Stigmella apicialbella -- moth
Daylily Leafminer (on daylily) -- Ophiomyia kwansonis -- fly
.. no common name (on White Snakeroot) -- Liriomyza eupatoriella -- fly
..no common name (on Penstemon) -- Phytomyza penstemonis -- fly
..no common name (on legume) -- Micrurapteryx occulta -- moth
..no common name (on Asteraceae) -- Ophiomyia parda -- fly
..no common name (on Mock Orange) -- Liriomyza philadelphivora -- fly
..no common name (on a goldenrod) -- Phytomyza solidaginophaga -- fly
..no common name (on Asteraceae) -- Ophiomyia carolinensis -- fly
Hellebore Leaf Miner (on hellebore) -- Phytomyza hellebori -- fly
..no common name (on magnolia) -- Phyllocnistis magnoliella -- moth

On June 28th 2019, there are/were a total of 41 species on this list. I assume that I will be adding more species to the list as time goes by.

Update July 10th 21019. I added one species on magnolia, and there is one other for a total of 43, but that last one:

..no common name (on Columbine) -- Phytomyza aquilegiana -- fly -- may be an incorrect addition.

Posted on June 26, 2019 16:46 by susanhewitt susanhewitt | 6 observations | 0 comments | Leave a comment

Fungal pathogens on plants in NYC

This year the spring and early summer in New York City has been very wet -- we have had a great deal of rain, and this seems to have favored the growth of fungi.

Here is a list of taxa of fungal plant pathogen species which I *believe* I have observed in NYC. This is very much a work in progress, so please forgive errors of various kinds, as well as general mistakes and incompleteness. I hope to add to this post and refine the text over time.

NOTE: Apologies to any real plant pathologists reading this: I am not doing any microscope work or culturing, so all of my IDs are just *guesses* based only on the appearance and symptoms of the affected leaves. Because of this, some (or perhaps many) of my IDs will turn out to be unreliable or just plain incorrect. As a result, in some cases the icon images for the species will have to be changed.

Some of these fungi were observed living in/on wild species of plant, and some were observed on cultivated plants. So far I have searched parks, gardens, street trees, and a small Urban Farm.

This first version is gleaned from the list of species currently in the project New York Mycological Society -- Fungi of NYC.

Mulberry leaf spot (on mulberries) -- Cercospora moricola
Pear Rust (on Callery Pear) -- Gymnosporangium sabinae
Black Rot (on Boston Ivy) -- Phyllosticta amplicida
Black Tar Spot (on maples) -- Rhytisma acerinum
Cercospora Leaf Spot on Hydrangea (on hydrangeas) -- Cercospora hydrangea
Red Dock Spot (on docks) -- Ramularia rubella
Quince Rust (on Serviceberries and others) -- Gymnosporangium clavipes
Hollyhock Rust (on garden hollyhocks) -- Puccinia malvacearum
Black Spot (on garden roses) -- Diplocarpon rosae
. . no common name (on Virginia Creeper) -- Phyllosticta quinquifolia
Spindletree Powdery Mildew (on Japanese Euonymus) -- Erysiphe euonymicola
. . no common name (on Wild Vetch and on Board Beans) -- Didymella fabae
. . no common name (on Common Mugwort) -- Puccinia tanaceti
Black Spot of Elm (on Elms) -- Stegophora ulmea
. . no common name (on Eastern Cottonwood) -- Drepanopezia brunnea
Lettuce Anthracnose (on Prickly Lettuce) -- Microdochium panattonianum
Dogwood Anthracnose (on Dogwood) -- Discula destructiva
Sycamore Anthracnose (on Plane trees) -- Apiognomonia veneta
. . no common name (on Heavenly Bamboo) -- Pseudocercospora nandinae
Cherry Leaf-Blight (on wild cherry) -- Blumeriella jaapii
Juniper-apple Rust (on Eastern Juniper) -- Gymnosporangium juniperi-virginianae
Bullseye Leaf Spot (on Japanese Maples) -- Phyllosticta minima
Powdery Mildew on Clover (on Red Clover) -- Erysiphe polygoni
Violet Rust (on wild violets Viola sororia) -- Puccinia violae
Oak Anthracnose (on white oak group) -- Apiognomonia errabunda
Cercospora Leaf Spot of Swiss Chard, Beets, and Spinach (on Beets) -- Cercospora beticola
Cercospora leaf Spot on Clover (on red clover) -- Cercospora zebrina
Hellebore Leaf Spot (on garden hellebore) -- Coniothyrium hellebori
Hypericum Rust (on garden St. John's Wort) -- Melampsora hypercorum
Ash Anthracnose Fungus (on Ash street trees) -- Gleosporium aridum
Peony Red Spot (on garden peony) -- Graphiopsis chlorocephala
. . no common name (on gardened Trilium) -- Urocystis trillii
Coryneum Blight (on Purple-leaved Plum) -- Wilsonomyces carpophilus

These species are only the ones where I think I could come up with an ID. I have many more about which am currently clueless, and which will probably have to remain so indefinitely for lack of lab work.

Posted on June 26, 2019 13:26 by susanhewitt susanhewitt | 7 observations | 0 comments | Leave a comment

June 02, 2019

Plant pests, pathogens, and galls -- why are they overlooked?

Over the last two years I have become particularly interested in observing plant pests, plant pathogens, and plant galls here in North America. Very often, finding them requires scanning plant life quite carefully as you progress slowly through a landscape.

In general we seem to have the habit of visually ignoring or avoiding looking at damage to plants. There is a sense that this kind of imperfection is "ugly" and unpleasant. There does not seem to be an awareness that damage to plants very often represents the survival work of other organisms, and that those organisms (viruses, bacteria, fungi, arachnids, insects, mollusks) can fairly often be identified to the species level by simply paying attention to the visual characteristics of the damage.

There is a parallel here. I have been interested in seashells since I was a toddler, but for many years I assumed that all the broken shells I saw on the beach were shells which had been whole when the animal died. I assumed that each shell had become broken in the process of being washed up, perhaps by being knocked against rocks, or dashed together with other shells in the waves.

But then I read Geerat Vermeij's 1993 book, "A Natural History of Shells". On page 94 he recounts how, on a beach in Guam in 1970, thanks to a comment from Lucius Eldredge, it dawned on Vermeij that damaged, repaired and broken shells are very often the result of predation. This insight struck him (and, in turn, me) with considerable force.

The damaged plants I see are like the broken shells, not to be avoided with disgust, but to be carefully "read" for the information they contain about the web of life.

Posted on June 02, 2019 13:51 by susanhewitt susanhewitt | 27 observations | 16 comments | Leave a comment

May 20, 2019

Two gall species on Boxelder Maple this spring

This spring I was excited to find two species of gall on a group of Boxelder Maple saplings on the edge of the Freshwater Wetland in Randalls Island, Manhattan, NYC.

On the Boxelder Maple there, the most common gall (extremely common this spring!) is the "Box Elder Pouch Gall Mite" (caused by mites). The mites create galls that look like little nodules on the upper leaf surface (see images one and two).

However, there were also some galls (not nearly as many) which were a lot larger, and were shaped like a soft money bags (but were quite hard). These galls each occurred on the rib of a leaflet (see the third image).

Here are my two other observations of other examples. of that larger gall:



And here is a gall on BugGuide that looks like those big ones:


It turns out that the big galls are indeed caused by "Box Elder Gall Midge", Contarinia negundinis, which is in the Family Cecidomyiidae - Gall Midges and Wood Midges.

So I thought that was cool, finding both galls caused by mites, and galls caused by midges, on the same plants.

Thank you to some input from Charley Eiseman.

Posted on May 20, 2019 13:58 by susanhewitt susanhewitt | 3 observations | 4 comments | Leave a comment

April 17, 2019

Getting ready for the City Nature Challenge?

Anyone reading this who lives in, or visits, NYC, and who would like some more detailed pointers for what to do, and how to do it, during the days of the worldwide City Nature Challenge (CNC), please feel free to contact me.

There are, conveniently, two weekdays and two weekend days we can use for CNC, so there is time available when anyone can make observations, no matter how busy they are.

1. Photograph anything and everything that is alive, except for pets, zoo animals, indoor plants and people.

2. Anything that was, or is, planted by people, is OK to record but please mark it "captive" or "not wild".

3. In order to rack up good numbers, please *do* photograph multiple different examples of the common species, as many as you can. Every pigeon counts. Every dandelion counts. 100 pigeons and 100 dandelions makes 200 observations!

4. Street trees are fine to record. But with most trees, so we can ID them OK, please try to take shots of the overall shape, the bark, a twig to show if the buds are opposite or alternate, and a leaf or flower if available. But if you can't do that, just do the best you can. Sometimes one image is enough to ID a tree if it is a distinctive species, like a Gingko.

5. You can photograph things when you are in a taxi -- see the four images here. You can photograph things through the window where you live or work. You can find plenty of things to photograph as you walk down a street, including small weeds in cracks in the sidewalk, in tree pits and planters. If you have the app open, it only takes a second to take a photo and hit "Save".

6. Perhaps most important of all -- it does *not* matter if you don't know what something is. You can mark it "plant" or "bird", or simply *Save* it with no ID at all! That is fine. It still counts as an observation, and the chances are that someone else will ID it.

Good luck to everyone and have fun!


Posted on April 17, 2019 20:55 by susanhewitt susanhewitt | 4 observations | 2 comments | Leave a comment

March 06, 2019

Helping a local NYC park become iNaturalist-ready

Carl Schurz Park is about a mile from where I live. It's on the East River. The park includes a very nice wide promenade/esplanade right along the river's edge, because that part of the FDR highway is covered over. Also, Gracie Mansion is inside the park -- that's the historic house where the mayor of NYC lives.

The views from the esplanade in the park are really pretty. Depending where you are standing, and which way you are facing, across a large expanse of water you can see the north end of Roosevelt Island, parts of Queens, Randall's Island (which I love), and Mill Rock. The large watery expanse is where, to the west, the East River becomes the Harlem River (a narrow inlet which joins up with the Hudson River). To the east, the water is called Hell Gate, and that water can be turbulent. Hell Gate eventually joins up with Long Island Sound. It's all part of the complicated geography of the estuary of the Hudson. The water is all saltwater, estuarine habitat.

Carl Schurz Park (CSP) itself is gorgeous, very pretty indeed. It is extremely well planted with mature trees, bushes and flowers, has very interesting and varied topography, and is superbly maintained. Carl Schurz Park Conservancy (CSPC) has been improving the park for many years now, and it has become an internationally known showcase, thanks to the efforts of a large band of dedicated volunteer gardeners.

Recently I was contacted by CSPC and I have been helping them get a little more completely set up with iNaturalist. There is now a Carl Schurz Park Biodiversity Project:


based on Carl Schurz Park Open Space:


In NYC, every park is a de facto nature preserve, no matter how well-gardened it may be. I would encourage anyone who either lives in this area, or visits it, to come check out this lovely park and all the wild critters that live there. We are keen to get more iNat observations. Please join the Carl Schurz Park Biodiversity Project. Thank you.

I have already led one CSP simple short nature walk for the volunteer gardeners (some wild ferns, mosses and lichens), and during the warmer weather I hope to lead a few more (one on spontaneous plants, one on insects and other arthropods, and maybe one on plant pathogens.) You are welcome to join us in our attempts to lean more about what lives in, and visits, this beautiful park.

Posted on March 06, 2019 16:14 by susanhewitt susanhewitt | 16 observations | 8 comments | Leave a comment

February 05, 2019

List of "mystery" leafminers worth investigating -- mostly in NYC

Charley Eiseman told me I had observed some interesting mysteries in terms of the leafminers that I photographed during 2018. Some of these may be new species.

I decided to create a journal post listing the mysteries, so that anyone who might want to investigate them can easily find my mystery observations, and then hopefully be able to find more of the leafminers while they are in the larval stage this year.

Please feel free to message me if you want more info about where exactly any of these were found. Also, bear in mind that by the date I photographed the mine, the larva may already have turned into a pupa, and the adult insect may have already have hatched out, and flown away.

Charley also explained to me that if I find any of these mystery leafmines where the mine is still occupied by the larva, and if I don't want to try to raise them myself, which is likely to be the case (even though it is quite easy to do), in that case I could send the leaves to him, so he can raise the larvae.


* A mystery leafminer in Rudbeckia. This one is relatively common in the Freshwater Wetland Wildflower Meadow on Randall's Island.
https://www.inaturalist.org/observations/14578192 -- July 21st 2018
https://www.inaturalist.org/observations/15882221 -- Aug 25th 2018
https://www.inaturalist.org/observations/15878574 -- two on one plant, Aug 25th 2018
https://www.inaturalist.org/observations/15919795 -- Aug 26th, 2018

* A mystery leafminer in Common Hackberry saplings, Celtis occidentalis Aug 26th 2018, Randall's Island.

* A mystery leafminer in a baby Cirsium plant, Sept 8th 2018, Randall's Island.

* A mystery leaf miner in Pennsylvania Everlasting, Gamochaeta pensylvanica, photographed by me on August 19th 2018. Unfortunately the host plant seems to me to be rather rare in NYC.

* A mystery leafminer in Populus Sept 12th 2018, Upper East Side.

* A mystery leafminer (might be the mallow leaf miner, Calycomyza malvae) in a cultivated plant known as Violettas, Anoda cristata in a community garden, Oct 28th 2018

* A mystery leafminer in leaves on saplings of Rose of Sharon, Hibiscus syriacus, Sept 1st 2018. Outside my building, Upper East Side. I need to get view of the underside of the leaf. This miner is likely to be Calycomyza malvae, but it needs confirmation.

A mystery leafminer on Chenopodium ?murale in Encinitas, San Diego County, California: Sept 28th 2018.

A mystery leafminer on Toyon in Encinitas, San Diego County, California: Sept 27th 2018.
Another of the same thing on Toyon in Encinitas, San Diego County, California: Sept 27th 2018.

In a leaf of Coastal Live Oak, Oct 1, 2018 -- not sure this one is a mystery.

Posted on February 05, 2019 17:10 by susanhewitt susanhewitt | 2 comments | Leave a comment

February 04, 2019

New species right in your backyard?

People generally seem to think that there is no way that an ordinary person can contribute significantly to scientific research, including the discovery of new species. However, that is emphatically not the case.

As I mentioned in my previous post, there is a brand new iNaturalist project called "Leafminers of North America":


In this new project, quite a few leafminer observations have already shown up for which the adult insect is currently a mystery. Some will turn out to be species that are currently unknown to science, and those species will need to be named and described.

We are fortunate that we have Charley Eiseman as a contributor here on iNaturalist. Charley is an expert on leafminers.

It is a relatively simple matter to attempt to raise leafminers to adulthood. It does not require a lot of equipment or time. And it is possible to find unknown leafminers in parks and wild spaces near where you live, without having to travel anywhere out of the way.

Charley Eiseman has created some instructions online about how to raise all different kinds of leafminers:


Charley has also written and illustrated an ebook that lists which known and unknown leafminers occur on any given plant:


I would encourage people, when they are out and about during the growing season this year, to look for leafminers, to make observations of them, and also to consider the possibility of raising some to adulthood.

Best wishes to all,


Posted on February 04, 2019 16:17 by susanhewitt susanhewitt | 2 comments | Leave a comment

February 03, 2019

A fascinating new project -- leafminers in North America

I imagine that most people have, once in a while, seen leafminer tracks -- white meandering lines or spotches within leaves of all kinds of plants? Mines are caused by the larvae of a surprising variety of different insects: moths, flies, beetles, and sawflies.

I am happy to announce that iNat has a brand new project, "Leafminers of North America", started by Charlie Eiseman, an outstanding leafminer expert. if you don't know much about leafminers, take a look at this project and the images it contains:


If you already have made some leafminer observations, please go ahead and add them to this project, and as spring and summer in North America progresses, please keep your eyes open for more leafmines.

There are leafminers in all kinds of different plants, and many leafminers are rather poorly known to science, which makes them even more interesting and important! There are many new species waiting to be discovered among leafminers.

Posted on February 03, 2019 18:25 by susanhewitt susanhewitt | 2 comments | Leave a comment