I have a few bits of news I’d like to share with you all:

First, I will be teaching a week-long workshop, Tracks & Sign of Insects and Other Invertebrates, at the Eagle Hill Institute in Maine next summer (July 29 to August 4).

Second, if that goes well, I will teach another course there devoted entirely to leafminers in summer 2019.

Third, a first edition of my leafminer book will be available just in time for that course!

I’ve decided to self-publish it in electronic form, in a series of 18 monthly installments beginning one month from today. There are a few reasons for this, which you can read about on my brand new Patreon page here. For those of you who are unfamiliar with it, Patreon is a crowdfunding website that allows you to support writers, artists, etc. by making monthly donations of whatever amount you choose. There are different rewards for donations that reach various thresholds. In my case, you get what amounts to a subscription to my big book of leafminers (we’re talking 1000+ pages before any illustrations are added) for just a few dollars a month, and if you feel like contributing something more towards my ongoing natural history work, there are “thank you” gifts including 8 x 10 prints, leafminer calendars, opportunities to join me in the field for a day, and (if you really want to go nuts) getting a species named after you!

I hope you’ll check it out. For a point of reference, I pay WordPress $2.50 per month so that no one has to see annoying and distracting ads on this blog. If all of my subscribers decided to chip in just that much, that would be enough for me to devote all of my time to solving and writing about natural history mysteries (I currently do this entirely in my spare time, which explains the sometimes long intervals between blog posts).

Okay, enough of that! More blog posts coming soon.


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Another Day, Another New Species

Five years ago this month, Julia and I were nearing the end of our first (and longest) trip around the US in search of leafminers. Walking up a desert wash near Tucson, Arizona, we encountered a leguminous shrub that was later determined to be “rosary babybonnets,” Coursetia glandulosa (Fabaceae).


A number of the leaflets had small, “underside tentiform” mines…


…which we collected in vials. Within a couple of weeks, about 20 adult moths had emerged.


If this all sounds or looks familiar, it’s because I wrote about it nearly four years ago when I was trying to determine what the host plant was. As I mentioned then, I had initially thought this moth would be a species of Macrosaccus because that’s the genus that typically forms underside tentiform mines on legumes, but after I looked at the known species in that genus, I wasn’t so sure.

For instance, here is an adult of Macrosaccus morrisella, which I reared from hog-peanut (Amphicarpaea bracteata):


Here’s Macrosaccus robiniella, from black locust (Robinia pseudoacacia; one wing is a little messed up, but you get the idea):


And here’s Macrosaccus uhlerella, from false indigo bush (Amorpha fruticosa):


All are basically solid orange with bold white markings and varying amounts of black—including a distinct black apical dot—whereas the Arizona moths were white peppered with black, with a little orange here and there. In April 2014, Julia and I visited Dave Wagner at his office in Connecticut, and after taking a quick look at one of the specimens he said it looked like a new genus. He boxed them up right then and there and sent them off to Don Davis, along with a few other interesting moths we had brought.

This spring, I sent Don some unrelated specimens, which after two months had somehow not made it to his office at the Smithsonian. When I asked one day if they had arrived yet, he searched around and found the specimens Dave had sent over three years earlier. Having just described my first moth with Don, I suggested that we do this one too. The genus wasn’t immediately clear to him, even after dissecting one, but ultimately the genitalia and wing venation indicated that Macrosaccus was a good fit after all. So we named it M. coursetiae, and the paper describing it was just published today*.

Here’s another adult of Macrosaccus coursetiae, which happens to be resting on an aborted leaf mine (tentiform mines start out flat and only visible on one leaf surface):


* Eiseman, Charles S. and Donald R. Davis. 2017. A new species of Macrosaccus (Lepidoptera: Gracillariidae: Lithocolletinae) from Arizona, USA. Zootaxa 4358 (2): 385–392.

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The Endless Diversity of Tiny Wasps, Continued

A couple of months ago I gave a sneak preview of some new species I found during the 2016 Berkshire BioBlitz on Mt. Greylock. One of them now officially has a name, thanks to a paper that was just published today*.

Platygaster vaccinii

Platygaster vaccinii (Platygastridae) is so named because it was reared from a gall on lowbush blueberry, Vaccinium angustifolium. I mentioned this gall in my original post about the BioBlitz, which included photos of a torymid wasp ovipositing into one of the galls.


The larva of the midge that causes the gall is bright orange when mature, and it drops to the ground to burrow and pupate. It probably overwinters before the adult emerges.


One of the larvae that emerged from the galls I collected died before I had a chance to put it in a jar of soil, so I sent it to Ray Gagné to examine. He told me he was filing it under Putoniella at the Smithsonian, since it most closely resembled this genus, but said it could be something else. He had never heard of a gall like this on blueberry. I have since found a few similar galls on highbush blueberry (Vaccinium corymbosum) and huckleberry (Gaylussacia frondosa), but so far this single parasitoid wasp is the only thing I’ve managed to rear from them. It emerged this spring, nearly a year after I collected the gall in June 2016.

The new paper describes another new Platygaster species reared from another unidentified and previously unknown midge gall. The host plant is goat’s rue, Tephrosia virginiana, so naturally the wasp is P. tephrosiae. The galls are common on Nantucket, and like the blueberry galls they consist of simple leaf folds.


Here’s what the (probably immature) larva looks like; Ray was only able to identify it to the supertribe Lasiopteridi:


As with the blueberry species, this one burrows into the ground when mature. My first attempt to rear it was a complete failure. Last July I got another two larvae from two more galls, and what emerged this spring were two platygastrids. As luck would have it, there was a female (which is what is needed to identify or describe a platygastrid)…


…as well as a male, which got to be the paratype.


I had sent these wasps to Peter Neerup Buhl along with a few others, all of which proved to be something interesting. A series of three females and four males from Nantucket were determined to be Trichacis virginiensis, a species described in 1893 but never before reared.


They came from galls on Virginia creeper (Parthenocissus quinquefolia) caused by the midge Dasineura parthenocissi. I also managed to rear a number of adult midges.


The other wasps (all of these are between 1 and 1.5 mm long, by the way) were several Mike Palmer had reared from midge galls in Oklahoma. Three that he reared from these same Virginia creeper galls were determined to be Platygaster munita, a species common in Europe but new to North America. Four additional specimens that he reared from galls on wild licorice (Galium circaezans) and horseweed (Conyza canadensis) all turned out to be Metanopedias eupatorii, a species Peter had described just six years ago from Trinidad!

Oh, I almost forgot, I also reared some specimens of Platygaster rubi from blackberry galls of Neolasioptera farinosa that I collected in my backyard. This was already a known host association, which seems to be a rarer thing to come across than a new species, as far as I can tell.

* Buhl, Peter N. and Charles S. Eiseman. 2017. Host records of five species of Platygastrinae (Hymenoptera, Platygastroidea: Platygastridae) from the United States, with the description of two new species of Platygaster. International Journal of Environmental Studies (abstract)

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The 2018 Leafminer Season Has Begun!

Today on a short walk in the woods behind my house, I found some leaf mines like these on bristly/swamp dewberry (Rubus hispidus):


A closer look at the one in the upper left corner of the above photo:


I first noticed mines like this several Novembers ago, and although there were larvae inside they seemed to have frozen to death, and I assumed they were the result of females of Metallus rohweri, the common sawfly miner of blackberry and dewberry, laying eggs a little too late in the season for their offspring to complete development. However, in early April of 2014, the author of this blog (Dana) wrote to me about larvae he had just found feeding in similar mines in Pennsylvania, while there was still ice on the nearby vernal pool, and wondered if he might be “on to something a bit unusual”. I mentioned my previous observation, and said “I don’t know if they can actually overwinter in the mines. Probably more likely these are offspring of adults that emerged from pupal cells in the ground a week or two ago.” As far as was known, all leaf-mining sawflies overwinter as prepupae in the ground.

He replied, “Interestingly, I had concluded these larvae overwintered in the mines.” He showed me a photo of some distinctly two-toned mines, and said, “My thoughts were that the whitish areas around the leaf edges are mines from last fall, and this spring those mines were expanded into the the rest of the leaf. This photo was taken 4/10/13… isn’t that rather fast leaf-mining for early April?  I think those mines were occupied.  If so, the sawflies were ahead of the Wood Frogs…”

I agreed that he seemed to be onto something. The following January, when the temperature was well below freezing, he wrote back with photos of occupied mines he had just dug out of the snow, and said that the larvae were feeding within a few hours of having been brought indoors. In May, he wrote again to report that he had succeeded in rearing an adult. When he showed it to me, and later when I examined the specimen, I couldn’t reconcile it with either Metallus rohweri or the raspberry leafminer, M. capitalis. It was oddly pale, like this one…


…in contrast with M. rohweri…


…and M. capitalis, both of which have dark abdomens.


I passed the specimen along to Dave Smith, and after some deliberation, he reported that it was Metallus ochreus, a species he had described in 1988. It was known only from adults caught in Virginia and Maryland, and its host plant was unknown, although Dave had noted that Rubus spp. were present near each collection site. He also noted in the original description that while most sawflies are spring fliers, all specimens of this species had been collected in late September and October. It was a little puzzling, therefore, why Dana’s specimen had emerged in early May, especially since he said it was from a leaf mine he had collected in late March or early April. I wonder now if there was a mix-up and it was really from one of the larvae he had found in January, although even that would be a faster turnaround than I later experienced…

…Because to make sure the biology of Metallus ochreus was properly documented, I collected a large number of larvae mining Rubus hispidus leaves here in Massachusetts in February 2016. Here’s what the mines looked like then; you can sort of see how the early, narrow part of the mine is paler than the rest, although it was much more striking in the examples Dana found:


It was hard to tell if the mines were occupied without picking the leaves and backlighting them:


All of the larvae finished feeding and burrowed into jars of soil within two weeks of my bringing them inside. In August, about six months after I’d collected the larvae, 23 adults emerged, and they were all M. ochreus as expected. They presumably would have emerged even later if I hadn’t brought them indoors in February, and this is consistent with Dave Smith’s impression that the species has a single generation with adults only appearing in the fall. This past spring I found some larvae near my house and checked on them every day; they dropped out of the leaves beginning in late April, and the last one hung around until May 3. Add six months to that, and it makes sense that early November is when the leaf mines start to be noticeable.

All this, along with new host and distribution data for the other North American Metallus species, was revealed last week when my latest paper was published:

Eiseman, Charles S. and David R. Smith. 2017. Nearctic Species of Metallus Forbes (Hymenoptera: Tenthredinidae): Biology and Distribution. Proceedings of the Entomological Society of Washington 119(4):551-564.

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Another Day, Another Mothy Mystery

Yesterday Cheryl Harleston of Yelapa, Mexico showed me these photos she had recently taken, and asked if I had any thoughts about them. She called the subject a “corral made of grains of sand.”


My immediate reaction was “I’ve never seen anything like it, but I love it!” She provided a few more details: “The size of the circle was 6 mm on the outside… There were several of these on several Xanthosoma leaves. I’ll be posting more photos later, as I went to see them today, and found no signs of the larva or the ‘beads’… Only dark rust-like circles where they had been…”

Xanthosoma is a member of the arum family (Araceae), and is one of several similar-looking plants known as “elephant ears” (Alocasia and Colocasia being other examples, which, I’m obliged to mention, have species of Marmara that mine their leaves).


As I waited to see the additional photos, I wondered, “Did each circle have a larva? And was there always feeding sign within the circle?” I looked at the photos a little more closely, and then asked, “Are you sure there was sand there, or could these all be beads of milky latex (does Xanthosoma have sticky sap)? If so, this could be a trick the larva uses to cut off the flow of sap so it can eat the leaf tissue within the ring. Some insects that feed on milkweed have similar strategies, though I don’t know of any that make a ring like this.”

Thomas Eisner’s book For Love of Insects has great photos of a red milkweed beetle (Cerambycidae: Tetraopes tetrophthalmus) biting into the midrib of a milkweed leaf to stop the flow of sticky latex, then eating the portion of the leaf beyond this without any problem. This feeding sign is a very common sight in milkweed patches.

DSC_1643july 10th 046

There is a photo in my book of a milkweed weevil doing something similar, but in the middle of the leaf. Anyway, Cheryl responded: “There is sand around, but I’m not sure that’s what it was…”

Her additional photos included two more views of the original ring (the second of these is backlit)…


…as well as these other examples:


It sure looks to me like my hypothesis was correct!  I believe there is no foreign material here, just little beads of sap forming where the caterpillar made little nibbles in the leaf surface. When the caterpillar had made enough of these nibbles to bleed out the disc of leaf tissue within the ring, it then got to have a meal. Seems like it would be easier just to find a different host plant!

As for what kind of moth this larva will turn into, I have no idea. Anyone else?

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A Hard-won Moth

You may recall that last spring I wrote a series of three posts that each highlighted something I hoped people would keep an eye out for; the last of these was a moth whose life history I had pieced together over several years. You can read the whole saga here, but to summarize:

In September 2011 I found this curious leaf mine on arrowwood (Viburnum dentatum) during my first survey of gallmakers and leafminers on Nantucket (this mine was actually on Tuckernuck, a tiny island nearby):


In August 2012, I found these mines abundantly on Nantucket, and I realized that each one entered the midrib, proceeded down the petiole, and into the stem:


This tiny larva popped out of a twig I collected, and when I showed it to Dave Wagner and Don Davis, they agreed that it looked like an early-instar Marmara (Gracillariidae):


The genus Marmara is mostly composed of bark/stem miners, with a few mining in the skins of fruit (notably the “citrus peelminer,” M. gulosa), and two feeding more or less exclusively as leafminers. All published accounts indicate that the bark/stem miners lay eggs directly on the stem, so this business about starting in the leaf and ending up in the stem was a little strange.

In June 2013 I continued to check out arrowwood plants and found that some of them had stem mines typical of Marmara:


As far as is known, all of the Marmara species that mine in woody stems have a single generation, with larvae hatching in summer, overwintering partially grown, finishing feeding in spring, and then pupating. Most species exit the stem before spinning a cocoon, and to rear them you need to find the larvae at just the right time, or else luck out and find one that spun its cocoon right on the host plant instead of wandering off to some hidden place where, if you happened to find it, you would have no idea what its host plant was. So in 2014 Julia and I flagged some arrowwood plants that had leaf mines, returning in December to dig them up, pot them, and bag them in transparent fabric with the hope of trapping any adult moths that emerged the following spring.


This was a failure, and we weren’t sure what to try next, until in July 2015 we stopped at a rest area in Illinois on our way to Colorado and spotted a couple of these bark flaps in association with Marmara leaf mines on an arrowwood:


These bark flaps are characteristic of the few Marmara species that don’t exit their mines to spin cocoons. The larva makes a semicircular cut in the bark at the end of its mine and spins its cocoon under this, causing the resulting flap to buckle:


So now all we had to do was return to Nantucket in June and look for the bark flaps, which we did last year. The problem was that the mines of this species are usually so deep in the bark tissue that they aren’t externally visible. Our solution was simply to search every single arrowwood plant we saw, whether or not it had any bark mines that we could see. We spent several hours doing this over the course of a few days, and we succeeded in finding a few dozen bark flaps, some of which were clearly old and empty, but some of which were not.

Between June 24 and July 2, three moths emerged!


They looked pretty similar to a number of other Marmara species. But in the fall, after my fieldwork had wound down, I reviewed the original descriptions of all 19 described North American species as well as the five South American ones, and I made a table detailing the wing pattern and various life history characteristics for each species. I discovered that all of the species that pupate in bark flaps at the end of stem mines are easily distinguished from this one by the wing pattern.

So I was confident that I had a new species. Now my problem was that nowadays to describe a new moth species, you need not only to describe the external features; you also have to dissect it and describe and illustrate the genitalia. This isn’t something I have learned how to do, and even if that weren’t an obstacle, the genitalia have only been described for a few Marmara species, so I wouldn’t be able to properly compare them with those of related moths. Having invested so much effort in learning the identity of this moth, I was determined not to just throw it on the pile of 100+ undescribed Gracillariidae that Don Davis has been working on for 50 years with the intention of publishing their descriptions in a big monograph someday… So I wrote to him and asked if he would be willing to collaborate on a paper describing this moth, in which he would deal with the genitalia and I would do everything else. He said he would be happy to.

So I wrote up my little early 20th century style description, and while I was at it I thought it would be fun to put together a table of all the known and suspected Marmara host plants based on published literature along with observations Julia and I had made on various trips around the country. I also incorporated other sources like observations posted to, and Mike Palmer (in Oklahoma) and Tracy Feldman (in North Carolina) came up with so many interesting new records that I added them as coauthors too.

I happened to get the paper back from review while I was in southern California this March, and Dave Wagner happened to be in the room. I started chatting with him about it and realized it was ridiculous to publish this master table of Marmara records without incorporating his data from the past 30+ years, so I added him as a coauthor too, and a few months later he found the time to go through all of his records and add them to the table. The result of our pooled observations together with the literature review is an annotated list of known or suspected Marmara host plants belonging to 115 genera in 50 families. A sizable chunk of these involve the citrus peelminer, which turns up on all sorts of plants in agricultural settings in southern California, but setting these records aside, it is clear that there are more Marmara species without names than there are described ones.

One more species has a name as of today though! The paper* was just published, so I can finally unveil the viburnum feeder’s (rather unsurprising) name, Marmara viburnella. Although the three adults from Nantucket are the only known specimens, our observations of leaf and stem mines indicate that this species occurs throughout the eastern US and Canada.

Before I sign off, here are some other bugs that are mentioned briefly in the paper but not illustrated. Our collections of M. viburnella cocoons yielded 33 parasitoid wasps in addition to the three moths, belonging to two species.

There were four of this Quadrastichus species (Eulophidae: Tetrastichinae)…


All from this one cocoon:


There is no key to North American Quadrastichus species, and as with Marmara, there are probably more undescribed ones than described ones.

The other wasps all belonged to this species of Ageniaspis (Encyrtidae):


Six of them came from this cocoon…


…and the other 23 emerged from an unknown number of cocoons that were collected together in one vial. They don’t match any of the species recorded from northeastern North America; I suppose a world revision of the genus will be needed before it can be determined whether they belong to any described species. Encyrtids are polyembryonic, meaning that multiple embryos can develop from a single fertilized egg, so it’s likely that all the wasps emerging from one moth cocoon came from a single egg. What’s crazier is that, based on what is known about other Ageniaspis species, the wasp egg was probably inserted in the egg or newly hatched larva of the moth back in the summer of 2015, with the wasp larvae biding their time within the moth larva as it mined around in its leaf, down the petiole and into the stem, overwintered, mined some more in the bark until it reached maturity, cut out its little bark flap, and spun its cocoon in the late spring of 2016, then they got around to devouring their host, emerging as adults a few weeks later.

And finally, some more benign associates. As Julia and I went around peeling back bark flaps in search of fresh cocoons, we found a variety of little springtails and beetles who thought M. viburnella’s bark flaps were good hiding places:

Anurophorus cf. septentrionalis (Isotomidae)…


Entomobrya nivalis (Entomobryidae)…


Contacyphon (Scirtidae)…


and Neapion (Brentidae).


Although this weevil can’t be identified to species just from the photo, it is likely N. herculanum, which is known to feed on arrowwood (I assume larvae develop in the seeds).

If each of the remaining mystery Marmaras takes me five or six years to sort out, that could keep me occupied for a while… I hope that by publishing a long list of unknowns that need to be investigated, I will inspire at least a few other people to join in the fun. So have at it!

* Eiseman, Charles S., Donald R. Davis, Julia A. Blyth, David L. Wagner, Michael W. Palmer, and Tracy S. Feldman. 2017. A new species of Marmara (Lepidoptera: Gracillariidae: Marmarinae), with an annotated list of known hostplants for the genus. Zootaxa 4337(2):198-222.


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Known Unknown or Unknown Unknown?

This 6-mm moth is a typical representative of the genus Cremastobombycia (Gracillariidae).


Larvae form “underside tentiform” mines on leaves of plants in the aster family (Asteraceae). The mine starts out as a flat blotch on the lower leaf surface, then becomes wrinkled and tentlike as the larva spins silk inside and consumes more of the leaf tissue.


On the upper surface, the mine is visible as a discolored yellowish patch.


The question is, what exactly is the host plant of this moth? The plant was growing in chaparral habitat in San Diego County, California, and it looked like this on March 12:

I posted photos of the plant to the Facebook Plant ID group, and the only suggestion I got was Dieteria asteroides (=Machaeranthera asteroides). The leaf shape is certainly similar, but photos of that species show an open, branching inflorescence quite different from this one. Looking for other possibilities, I checked out every mention of Cremastobombycia in my book manuscript and looked at photos of all the recorded host plants that were unfamiliar to me. I found one promising lead: Powell (2002)* mentions an undescribed species that feeds on Hazardia and Isocoma in California, and my mystery plant looks a lot like Harzardia squarrosa.

However, I’m not sure the inflorescence of that plant is quite right either, and apparently the variety of H. squarrosa that occurs in San Diego County is var. grindelioides, which looks like a pretty different plant. The Flora of North America key to Hazardia squarrosa varieties indicates that var. grindelioides is distinguished by having non-resinous leaves; I don’t remember this plant being sticky, but my close-ups of the leaves clearly show that they are covered with stipitate (stalked) glands; it seems to key to var. squarrosa, if it is in fact Hazardia.

So, I’m hoping that someone out there who knows southern California plants well can confidently identify this plant from my photos. Here are the other ones I took:


The stipitate glands are visible in this shot of the moth’s pupal skin protruding from the moldering leaf:


* Powell, Jerry A. 2002. Lepidopteran caterpillars feeding on California native plants. Fremontia 30(3-4):5-14.

Edit, 10/15/2017 – Here is what Barry Prigge, former curator of the the UCLA herbarium, had to say about this plant:

Hazardia squarrosa var. grindeloides.   Hazardia squarrosa is a variable species over its range of distribution, and identification, especially to variety, is often rather tentative.  Flowering material would be helpful, but the vegetative, fruiting inflorescences, and distribution match that of var. grindeloides.  Inflorescences can appear quite different from flowering to fruiting specimens.  Check out our description and Tony Valois’ photos of this species at:
and click “ANF Description” at end of images.  Our plants are obscurely glandular, but evidently there is more variation in the glands than what we described for plants from the Sta Monica Mtns.
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