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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Another Progress Report (Goofing Off in the Desert)

Remember at the beginning of last year when I announced that I had finished making keys to the known leaf mines on every plant genus in the US and Canada? I noted that “this project can never really be finished, because more species and life histories are being discovered all the time.  But I’ll consider it to be time to start looking into publishing this thing when I’ve finished writing all the introductory chapters, which could conceivably happen by the end of this winter.”

Well, it didn’t happen by the end of that winter. I did do some work on the introductory chapters, but then I got bogged down in writing several large papers describing new species and documenting new information about already named ones. Then it was time to go back to working full-time, which (because much of my work is outdoors) resulted in the collection of ever more leafminers to rear, and dealing with those left little time in the summer for making progress on the book. Some time in December things wound down enough for me to focus on writing again, but once again I gave priority to properly documenting new discoveries. I planned to get to the book later in the winter and in early spring, but then Eric LoPresti invited me and Julia to come and play in the California desert during the “super bloom”. The New England winter was seeming unnecessarily cold and dark and long, so we didn’t take much persuading.

On the way out, we spent some time exploring New Mexico and Arizona, with a little time in Arizona and Texas on the way back. Everywhere we went, we found previously unknown leafminers. In fact, now that I’ve finally had a chance over the past few weeks to sort through my pictures from the trip, I’d say at least 90% of the things we found required adding something to the book. So in a way, I’m making lots of progress, but it’s in the form of expanding what I’ve already written rather than writing those introductory chapters. But wouldn’t it be a shame if I published a “complete” guide to leaf mines that left out so many easily observed southwestern species?

We’ll see how this winter goes—I’ve still got six months of photos to sort through and more papers to write, but I’m optimistic that some substantial forward progress will be made. In the meantime, here are some pretty pictures from the desert (all taken at Anza-Borrego Desert State Park, California, between March 8 and 11).





A sawfly (Tenthredinidae) visiting flowers of Phacelia (Boraginaceae) or something similar.


This moth is Noctueliopsis aridalis (Crambidae).


Dry, cracking mud in this wash was all that remained of the downpour that brought on the bloom.


Lupine shadow.


There was a variety of fancy blister beetles (Meloidae) out and about. This one is Eupompha elegans elegans.


As I wrote about here, the tiny larvae of blister beetles ride solitary bees back to their nests, where they devour the bees’ provisions. One of the known hosts of E. elegansHesperapis (Melittidae), was visiting a flower not far from this beetle.


Julia in Coyote Canyon.


Further down Coyote Canyon, I found these tracks and bill marks of what must have been a snipe probing for food in the mud along a creek. In the east I’ve seen similar feeding sign left by woodcocks.


Another blister beetle, Cysteodemus armatus.


Desert five-spot (Malvaceae: Eremalche rotundifolia), a little mallow on which we found occasional leaf mines.


Sand-verbena (Nyctaginaceae: Abronia), a plant for which Eric has unrelenting enthusiasm. It also has its share of leafminers, one of which we discovered with Eric a few days earlier in another part of California.


A hillside in Hawk Canyon covered with lupine and… oh, one of those evening primroses I could never get straight. There were so many new plants to learn that if something didn’t have any leafminers on it, the name just went in one ear and out the other.


Blister beetle #3: Lytta magister. A number of these were buzzing around on top of a ridge.



In some places the ground was carpeted with these monkey flowers—I think Mimulus bigelovii (Phrymaceae).


Justicia californica (Acanthaceae), known as chuparosa or hummingbird bush.


Jewel beetles (Buprestidae: Acmaeodera vernalis).


Desert harvestman (Sclerosomatidae: Eurybunus).


Eric found this mating pair of Timema (Timematidae), a type of stubby walkingstick that occurs only in the Southwest.


John Ascher, who has identified pretty much every bee I’ve posted on this blog, says the bee in this photo is a male of either Dufourea (Halictidae) or Hesperapis.


More and more Lytta magister.


Ornate checkered beetle (Cleridae: Trichodes ornatus) in a flower of desert chicory (Asteraceae: Rafinesquia neomexicana).


Tiny checkerspot (Nymphalidae: Microtia dymas).


Yellow brittlebush (Asteraceae: Encelia farinosa), red chuparosa, the bluish ones are probably Phacelia crenulata, and the pink ones are more monkey flower.


Megandrena enceliae (Andrenidae).


Red-eared blister beetle (Lytta auriculata), turning pink petals into poop.


Sand blazing star (Loasaceae: Mentzelia involucrata).


These little Perdita bees were big fans of the Mentzelia.


And finally, a leafminer. This “ribbed cocoon maker moth” (Bucculatricidae) was found on desert globemallow (Malvaceae: Sphaeralcea ambigua) and appears to be Bucculatrix sphaeralceae.


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Why You Should Let Me Collect Bugs On Your Land With Impunity

Last year I posted some of my most interesting finds from the June 18 Berkshire BioBlitz on Mt. Greylock—at least, the ones that were most immediately visually interesting. There were several more significant discoveries that I didn’t want to write about until I had the whole story. One was this nondescript green sawfly larva that Julia noticed on a beech leaf, right near the one on an oak leaf that was busy getting parasitized by ichneumonids.


I had never seen a sawfly larva feeding on beech before, so I put it in a vial to see if I could rear it. After consulting with Dave Smith, who has studied sawflies for about 50 years, it appears that no one has seen a North American sawfly feeding on beech before. Now, the vast majority of sawfly larvae that I collect burrow into soil (as this one did at the end of June) and don’t emerge as adults until the following year. So I often don’t pay much attention to my jars of soil containing sawfly larvae, but something made me take a peek in this one on July 15. I was glad I did, because I found this snazzy green adult sawfly inside:


I sent it to Dave, and he identified it as Nematus appalachia (Tenthredinidae), a species he had described just 12 years earlier from adults caught in Malaise traps in the Appalachians of North Carolina, Tennessee, and West Virginia. So this one found on a mountain in Massachusetts represented a pretty dramatic expansion of the species’ known range as well as the discovery of its host plant. We reported all this in a short paper that was just published a few days ago*.

It’s worth mentioning here that the Massachusetts Department of Conservation and Recreation (DCR), which manages the Mount Greylock State Reservation, almost didn’t allow collecting of specimens at this BioBlitz event. Fortunately, our new state botanist, Bob Wernerehl, managed to secure permission at the last minute. Thanks to this, I was also able to collect and rear a new species of leaf-mining dark-winged fungus gnat (Sciaridae)…


…a new species of platygastrid wasp (a parasitoid of what is likely an undescribed species of gall midge, but unfortunately no adult midges emerged)…

Platygaster vaccinii

…and a new species of leaf-mining fly (Agromyzidae):


I’ve sent these specimens off to Germany, Denmark, and Canada, where my taxonomist collaborators are working on describing them. I’ll have more to say about these species once their names have been properly published, hopefully within the next year. I was thinking about saying something here about how odd it is that I have to send most of my bugs outside the US to get them identified, and musing about how this might relate to the fact that it’s so hard to get permission to collect in this country in the first place… but instead I’d just like to commend the owners and managers of natural areas out there who encourage nature study rather than forbidding it.

* Smith, David R., Julia A. Blyth, and Charles S. Eiseman. 2017. Nematus appalachia Smith (Hymenoptera: Tenthredinidae) feeding on Fagus grandifolia (Fagaceae). Proceedings of the Entomological Society of Washington 119(3):518-519.


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How It All Started

Today is an anniversary of sorts. The first weekend of August 2007, I was up in Vermont to perform at the Champlain Valley Folk Festival with my band, PossumHaw, which had formed while I was in grad school in Burlington. Before heading home—ten years ago today—I visited a few properties of the Winooski Valley Park District to do some consulting work (another lingering connection from grad school), and at Muddy Brook Park in South Burlington this caught my eye:


Leaf mines on poison ivy leaves. Just a week earlier, I had sent a proposal for an “invertebrate tracks and sign” book to Mark Allison, nature editor for Stackpole Books, and had received a positive response. So I was beginning to photograph in earnest everything that looked like a bug might have done it. I don’t think I had taken any particular notice of leaf mines before that; the only photograph I am aware of having taken of one before that is this one from August 9, 2004:

Phyllocnistis mines on aspen leaf

And it certainly doesn’t take a leaf mine fanatic to appreciate the artistry of Phyllocnistis populiella (Gracillariidae) on a quaking aspen leaf. Anyway, these poison ivy mines were especially interesting because the adult moths were emerging from them just as I happened to walk by.


I didn’t have a fancy macro lens at the time—in fact, I refrained from getting one until I finished the book, because I wanted to focus on creating a guide to things people could actually see—but for what it’s worth, here is a closer crop of the moth on the left (its pupal skin can be seen poking out of the leaf in the upper half of the frame):


That winter, I discovered the ID Request section at, and began occasionally posting photos of insects I had associated with various tracks and signs. On March 25, 2008, I got around to posting a photo of this moth, and on April 15 Terry Harrison saw it and confirmed that it was Cameraria guttifinitella (Gracillariidae). This happens to be the first of over 2000 species for which I’ve created a guide page as a BugGuide editor, but more importantly, something clicked as I perused Terry’s website,, and as Terry continued to help me solve moth-related mysteries. Working as a field botanist while collecting information about the types of evidence all sorts of invertebrates leave behind, I couldn’t help but become fascinated with leafminers. Their specificity both in choice of food plant and in the type of pattern they produce makes them the most satisfying insects to track, because they can so often be identified all the way down to species based just on what they leave behind.

It didn’t take me long after finishing Tracks & Sign of Insects before I set out to create a “complete” guide to leaf-mining insects—an ever receding target. Just now, as I scrolled back through my recent photos to look for a Cameraria to include here, I noted that the last three leaf-mining moths I photographed were probably undescribed species. Here, however, is one I reared last week from hazelnut (Corylus americana) that we can call Cameraria corylisella with reasonable confidence. I still haven’t gotten around to getting a better photo of C. guttifinitella, so this will have to do for now.




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Mystery Lakeside Jewels

It’s been a busy five months or so… At the moment, for instance, I’m on a ferry on the way to Nantucket for my seventh annual visit to search for leafminers, gallmakers, and other obscure insects to add to what’s known about the island’s fauna. This is a short break from the long days of slogging through swamps and bogs that are occupying much of my summer. I hope to get back to posting more regularly in a month or so, but right now I just wanted to dash off a quick post to share some mystery objects that recently caught my attention. They were posted to the Facebook Plant Identification group, and I thought they deserved to be put on display for all to see, rather than buried in an endless stream of photos of plants looking for names.

They were found and photographed by Jeff Hollett of Northwest Territories, Canada. He found them “under rotting, wet tree stumps in swampy lakeside habitat.”


Nobody had a clue what they were. A few people suggested some kind of wasp gall; I was sure that wasn’t right, but didn’t have a better suggestion. I thought maybe some kind of fungus. Fortunately, Jeff did what so few people who discover one of these mysteries do: he went back and collected some to investigate.


They’re leech egg cases! There were several baby leeches inside each one.

As far as I knew, all leech egg cases look more or less like this. As described somewhere near the beginning of my Tracks & Sign book, leeches and earthworms make their egg cases by secreting a proteinaceous substance that scoops the eggs and sperm off their bodies as they slide it forward; once shed from the front end of the body, it hardens to form a structure that is typically smooth and pinched together at both ends. How the ones that Jeff found came to be faceted and covered with those little projections remains a mystery to me.


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