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.

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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:

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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)…

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…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):

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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:

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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.

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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):

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That winter, I discovered the ID Request section at BugGuide.net, 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, microleps.org, 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.”

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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.

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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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Introducing Fenusa julia

The summer before last, Julia and I took a trip out to Colorado and some Midwestern prairies, partly to visit some friends and partly to fill in some gaps in our leafminer explorations (which had taken us all around the perimeter of the US, but had so far missed the whole area bounded by Ohio and California, South Dakota and Texas). One day we were wandering along a creek near Aspen when Julia spotted some mines on a wild rose, which I later determined to be Rosa woodsii.

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They were clearly sawfly larvae, but I was sure there were no known rose-mining sawflies in North America, since there are only 30 or so species to keep track of. So we collected a dozen of them, and by the end of the day they were already starting to exit their mines.

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Fortunately, I was prepared with a jar of soil for them to burrow into, and within a few days they had all done so. I refrigerated the jar over the winter as described here, and a month after I took it back out of the fridge, seven adults emerged.

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I sent them off to Dave Smith to examine, and they turned out to be most similar to Fenusa ewaldi, a species he had described just a few years earlier, reared from larvae mining rose leaves in Russia. The two species look pretty much the same, but he found differences in the antennae, eyes, wings, and ovipositor. Julia had made me promise not to name any flies after her, but she never said anything about sawflies, so I decided to call the new species Fenusa julia. The paper describing it appeared online today, in the so-called April issue of Proceedings of the Entomological Society of Washington*.

Just like Scolioneura vaccinii, which we discovered on our first big leafminer road trip, Fenusa julia is the first native member of its genus to be found in North America. There are also three introduced European species here: F. dohrnii on alder, F. pumila
on birch, and F. ulmi on elm.

* Smith, David R. and Charles S. Eiseman. 2017. A new species of Fenusa (Hymenoptera: Tenthredinidae) mining leaves of Rosa woodsii Lindl. (Rosaceae) in North America. Proceedings of the Entomological Society of Washington 119(2):233-238.

 

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Cocoon Within a Cocoon Within a Cocoon

The diamondback moth (Plutellidae: Plutella xylostella) is a European species that is now found all across North America, the larvae feeding on various plants in the mustard family (Brassicaceae). Apparently it’s considered a pretty serious pest, but I’d take it over Cabbage White caterpillars (Pieridae: Pieris rapae) or Cross-striped Cabbageworms (Crambidae: Evergestis rimosalis) any day.

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In fact, I was excited to find its tiny leaf mines in our broccoli leaves a few years ago, after stumbling on the fact in the course of my research on leafminers that this species starts out as one.

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The mines are just a few millimeters long, barely larger than the bodies of the first-instar caterpillars. In the backlit photos below, you can see a larva swiveling its head to feed, keeping its tail end at the entrance to dispose of its frass.

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The larvae soon abandon their mines to feed externally on the lower leaf surface. The one below is face to face with the shed head capsule from an earlier instar, which it has carefully eaten around. The rest of the exuviae are to the larva’s right (below it in the photo).

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Only when nearly full-grown do the larvae eat little holes all the way through the leaf.

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(Incidentally, the yellowing leaf is a result of my having picked it to raise the larvae, not damage caused by the larvae.) When mature, the larva spins an open-mesh cocoon, and the green pupa is plainly visible inside.

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When you see a solid cocoon within the open-mesh cocoon, as in this one on peppergrass (Lepidium virginicum), that’s the work of an ichneumon wasp (Ichneumonidae: Campopleginae: Diadegma insulare) that was developing inside the caterpillar all along. After the caterpillar spins its cocoon, the wasp larva finishes devouring the caterpillar, then spins its own cocoon to pupate inside.

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Here’s the wasp that emerged from that cocoon:

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Thanks to Andrew Bennett at the Canadian National Collection of Insects, I just learned that this wasp is Isdromas lycaenae (Ichneumonidae: Cryptinae), a hyperparasitoid that fed as a larva on the parasitoid larva. I can only assume it spun its own cocoon within the Diadegma cocoon within the diamondback moth cocoon.

Here’s a Diadegma that emerged from the cocoon of a leaf-mining moth (Gracillariidae: Parectopa thermopsella) I was trying to rear a couple of years ago. No idea what species it might be, if it even has a name; there are 41 described Diadegma species in North America, but there are no keys to identify them.

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Hiding in Plain Sight

…would be a suitable title for any of the posts about tiny bugs that I regularly write here, I guess, but it seems especially appropriate in this case. The story begins in September 2012, when occasional BugGuide.net user Greg Dodge posted this photo of blotchy white leaf mines on white clover (Fabaceae: Trifolium repens) he found in Durham, North Carolina. They didn’t seem to match any mines known from this common plant, so the few of us who pay attention to such things were intrigued. He put them in a vial, and eleven days later, he posted photos of the adult moths that emerged. The moths appeared to be Porphyrosela desmodiella (Gracillariidae), a relatively straightforward identification since this was the only species of Porphyrosela in North America. Here is an adult of P. desmodiella that I reared from its namesake, Desmodium (tick trefoil), in Arizona (also in the fall of 2012, as it happens).

Here is the leaf mine on Desmodium, as viewed from above and below:

This is a typical “underside tentiform” mine, which starts as a flat blotch on the lower leaf surface, then the larva spins  silk inside it, which contracts as it dries and causes the leaf to buckle and form a “tent”.  Porphyrosela desmodiella is known to mine leaves of several legumes in addition to Desmodium, so it didn’t seem out of the question that it should mine clover leaves on occasion. The problem was, P. desmodiella always makes underside mines, whereas these clover mines were on the upper surface.

After I moved Greg’s photos to the Gracillariidae section for further contemplation, he commented: “The adult moth seems to be Porphyrosela desmodiella. The question is, why is the mine, or tent, that I photo’d different from what is described for this species here on BugGuide, that is, on the upper surface of the leaf not the underside? Although I found several spent pupal cases attached to the vial in which the moths were raised, I did locate one within one of the curled up leaflets. Interestingly, I found this site with a photo of a tent which looks remarkably like the one that I photo’d but which belongs to Porphyrosela minuta from southern South America. Anybody?”

Porphyrosela minuta was described in 1953 from specimens reared from white clover in Argentina. The paper Greg found documented the life history of this moth on white clover in Uruguay. It is not known to use any other host, which is odd since the moth is apparently native to South America and the plant is native to Europe (where no species of Porphyrosela are known to occur).

Terry Harrison quickly responded that it would be great if Greg could send the specimens to Don Davis at the Smithsonian so that he could examine them. Alas, Greg reported that “they all flew off except one which was unfortunately, and unintentionally, spread across the inside of one of the vials. I may try to rear more.”

Two months later, Thomas Wilson posted photos he had taken of similar leaf mines in Baltimore, Maryland, a few weeks before Greg found them in North Carolina. When Thomas left a comment on Greg’s post pointing this out, Greg replied: “I had planned on shipping off a specimen of an adult to Don Davis for identification but the only specimen that I had was a smashed individual that was later eaten by a roach (my fault completely, I left it sitting around too long in a vial with the lid partially open). I tried to rear more but was unsuccessful. Maybe next season.”

Nothing more was said about the subject for three years. Suddenly, in August 2015, these Porphyrosela mines on white clover were found by Domingo Zungri of Roseville, California; Mike Palmer of Stillwater, Oklahoma; and Tracy Feldman of Durham, North Carolina. I encouraged them all to collect lots of mines, not wanting to hear any more stories about the one(s) that got away or were smooshed and then eaten by roaches. I also told my friend Eric LoPresti at the University of California (Davis) to keep an eye out for them. Mike, Tracy, and Eric all came through; Tracy also found them where he teaches in Laurinburg, not far from the South Carolina border, and although Eric didn’t see any in California, he happened to be in Durham that month and stuffed a sandwich bag full of the mined leaves.

As a result, Porphyrosela minuta is now properly documented in North America. Voucher specimens are deposited at the Smithsonian and in the Canadian National Collection, and our paper* was published in January. (The print version finally showed up in my mailbox yesterday, which reminded me that I should write this post.)

When J. F. G. Clarke described Porphyrosela minuta as a new species, he stated that it was extremely similar to P. desmodiella, and apart from details of the genitalia, the only difference he noted was that P. minuta has a black terminal line on the forewing that P. desmodiella lacks. His description was based on a single male and four females. With several times that many specimens in front of me, I noticed another difference in the wing patterns of the two species. In the reared examples of P. desmodiella I examined, the second fascia (stripe) on the forewing was approximately perpendicular with the wing margins, bending somewhat so that it paralleled the first fascia toward the costal margin (the bottom of the wing when a live moth is at rest). The space between the fasciae along the costal margin was about 20–30% larger than on the dorsal margin. In contrast, on P.
minuta the first and second fasciae are angled equally but in opposite directions, so that the space between them on the costal margin is about twice that on the dorsal margin.

That may sound like a subtle distinction, but take a look at the two side by side and I think you’ll see (P. desmodiella above, and P. minuta below):

The black markings are much bolder on this P. minuta than on this P. desmodiella, but unfortunately this doesn’t seem to be a consistent difference, and that also goes for the terminal line mentioned by Clarke. The difference in the angling of the second fascia, on the other hand, seems to be entirely consistent.

Although I’ve now coauthored several new insect species, I have always just contributed the parts about the larval biology and natural history, so finding this difference sort of felt like my first real foray into taxonomy. Having made this little discovery, I took a look at the photos of Porphyrosela desmodiella on BugGuide.net, and was surprised to find that all of them—with the sole exception of one that MJ Hatfield had reared from an underside tentiform mine on Lespedeza (bush clover) in Iowa—were in fact P. minuta! Once I realized this, it turned out that the first photo of P. minuta in the US was this one of an adult found in Louisiana in June 2008. Tracy remembers seeing the mines and an emerging adult sometime between 2000 and 2002 in the same lawn in Durham, NC, where Eric collected them in August 2015, but he was unaware of their significance at the time.

So is this some terrible new invasive species that has swept across the country? I don’t see why anyone should be bothered about it; there’s plenty of clover to go around, and clover isn’t native either. And the leaf-mining larvae are providing food for at least three species of parasitoid eulophid wasps, which as far as I know are all native:

Hemiptarsenus sp.

Sympiesis sericeicornis (I’ve reared this one from P. desmodiella as well)

Pnigalio coloni

As far as I’m concerned, anything that increases the biodiversity of lawns—an all too dominant feature of our landscape—is a good thing. I’ll be curious to hear if anyone finds these clover leaf mines anywhere else in the US. Right after our paper was published, I heard from someone in southern Brazil that P. minuta has been found there as well, for a total of three adjacent South American countries, plus the five scattered states in the US mentioned above, where this moth is known to occur. I would love to know what its original host plant was in South America, and how it managed suddenly to become established from coast to coast in North America before anyone noticed it.

* Eiseman, Charles S., Tracy S. Feldman, Eric F. LoPresti, and Michael W. Palmer. 2017. First North American records of Porphyrosela minuta Clarke (Lepidoptera: Gracillariidae), with notes on its native congener, P. desmodiella (Clemens). Proceedings of the Entomological Society of Washington 119(1):18-23.

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More Evening Primrose Moths

Two years ago I wrote about the striking pink and yellow moths I found resting on evening primrose (Oenothera biennis) flowers by my mailbox, and how I later found the caterpillars feeding on the young seedpods. That same summer, I found two other kinds of moth larvae feeding on the evening primrose plants along my driveway. One was a leafminer I had reared before from the sundrops (O. pilosella) in my mother’s garden, but hadn’t noticed on evening primrose before.

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Like nearly all leaf mines on the evening primrose family (Onagraceae), these linear ones on Oenothera are made by a species of Mompha—in this case M. argentimaculella.

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Mompha argentimaculella was supposed to be the only leafminer on Oenothera, so I was surprised when one day I noticed distinctly different mines on the evening primrose along my driveway. Instead of narrow, linear mines with frass deposited all along their length, these were blotches with all the frass packed at the beginning.

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In one case I found two larvae whose mines had merged.

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The reddish larvae were superficially similar to the Mompha larvae…

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…but the adults turned out to be something entirely different: Aristotelia isopelta (Gelechiidae).

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There was no published host or natural history information available for this species, nor was there any reason to suspect an Aristotelia, since members of this genus are normally leaftiers. However, when I sent a specimen to Jean-François Landry to deposit in the Canadian National Collection, he informed me that they have other specimens reared from evening primrose in Quebec in the 1960s. Also, Terry Harrison told me he once had this moth emerge from a batch of leaves from California that also contained Mompha leaf mines. Terry’s leaves were not evening primrose but Epilobium, another member of the same family. Epilobium species are known as “willow-herbs”, apparently because of their willow-like leaves.

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Their seeds are also dispersed on the wind by tufts of fluff in a way somewhat similar to willow seeds. The long, curved, empty seedpods give the dead plants a distinctive look in the winter:

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That same summer I was finding all the interesting evening primrose moths along my driveway, I was working in wetlands all over western Massachusetts and kept finding leaf mines on a common wetland plant, Epilobium ciliatum.

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These certainly looked Mompha-like, but the only Epilobium miner known to occur in eastern North America was M. epilobiella. This is an introduced European species that starts out as a leafminer, but older larvae feed externally in clumps of webbed leaves. I collected a bunch of larvae, and they continued mining leaves throughout their development. Here you can see one larva spinning a cocoon on the underside of a leaf while two more, nearly mature larvae mine toward it (as you can also see in the above photos, these larvae mine belly-up):

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The adults were pretty little orange-marked moths:

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Jean-François and Terry concurred that they were Mompha locupletella, a species previously known only from Europe. Unlike M. epilobiella, however, this appears to be a native Holarctic species that simply was missed by earlier microlepidopterists—or at least, no one had gotten around to publish anything about it. There are at least a couple of other Mompha species in this category, another being M. raschkiella, which feeds on fireweed (Chamerion angustifolium), a plant formerly placed in the genus EpilobiumMompha raschkiella was described from Europe in 1839 and has been found all across Canada, but its existence in North America wasn’t published until 2010. For details of many other Mompha species that have yet to be documented or even named, we’ll have to wait for Terry’s big publication on the genus, which is still some years off. But in the meantime, I summarized what is known about the leafminers of the evening primrose family in a paper that was published recently alongside the one describing Zygoneura calthella:

Eiseman, Charles S. 2016. North American leafminers (Lepidoptera: Gelechiidae, Momphidae) on the evening primrose family (Onagraceae): new host, parasitoid, and distributional records. Proceedings of the Entomological Society of Washington 118(4):510-518.

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