The Long-Lost Snow Fly

This morning as we were shoveling the season’s first snowfall from our driveway, I wondered aloud whether this would be the winter I finally get to see another one of those wingless crane flies, sometimes referred to as “snow flies” (Limoniidae: Chionea spp.). They’re not quite as glamorous as snow scorpionflies, but they’re interesting curiosities nonetheless. It’s been eleven years since I last saw one, which means I’ve never had an opportunity to photograph one since acquiring a decent macro lens.

After we finished shoveling, we headed out for a quick walk in the woods behind our house. We had only made it to the corner of the yard when I had to dash back inside to get my camera, because a Chionea was standing there waiting for us! Julia kept an eye on it while I was gone; it wandered into one of our footprints, and had just finished climbing back out when I returned:


It alternated between walking and standing still for seconds at a time, so I was able to try various angles and levels of magnification:


Something I didn’t realize until I was processing these photos is that these flies aren’t quite wingless. In all true flies (Diptera), the hind wings have been reduced to little knobby-looking things called halteres. I knew that Chionea species had these, but on this individual you can see that the forewings are still present too—they’ve just been reduced to a fraction of the size of the halteres. If I had known that when I was taking these pictures I could have done a better job showing it, but in this cropped-down side view you can at least see what I’m talking about:


The onset of winter is no reason to stop looking for bugs, as I’ve previously written about here and here and here.


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Discovering New Species Along the Driveway

In this photo from May 2015, I was celebrating our newly installed solar panel’s generation of its first kilowatt hour. But unbeknownst to me at the time, the photo also shows where I collected the type specimens of two new speciesthe descriptions of which have just been published in a paper I coauthored with Owen Lonsdale*.


Along the driveway at the left edge of the frame, in September 2013 I had collected some basal leaves of daisy fleabane (Erigeron annuus) that were being mined by fly larvae.


When finished feeding, the bright yellow larvae popped out of the leaves and formed shiny black puparia.


In my “Fixing the Lawn” post I showed one of the two female flies that emerged a few weeks later, noting that “I won’t know exactly what they are until Owen Lonsdale examines the specimens.” Fortunately there was also a male among them, since agromyzid taxonomy is largely based on details of the male genitalia.


Owen determined that these flies belonged to an undescribed species, so we named it Phytomyza erigeronis, and this male was designated as the holotype. The rest of the type series consisted of six other specimens from my front yard, plus nine reared from leaf mines Julia and I collected at the Connecticut BioBlitz in 2016. Two other North American Phytomyza species are known to form linear mines in fleabane leaves; so far this is the only species I’ve managed to rear, but based on published descriptions the mines of P. erigerophila and P. peregrini are shorter (3-6 cm vs. well over 7 cm).

A year after the solar panel was installed, I collected a few leaves like this one from an aster (Symphyotrichum laeve) that was growing right under the panel.


This mine appears to be empty, but the sneaky larva switched to the lower leaf surface at the last minute and formed its puparium there (in the upper left corner of the photo below).


This distinctive leaf mine, with the frass deposited in large, widely spaced lumps along its length, is attributed to Ophiomyia quinta in Tracks & Sign of Insects. Here’s the story behind that: In 1969, when Kenneth A. Spencer revised the Agromyzidae of Canada, he had a whole bunch of undescribed Ophiomyia species to deal with that had nothing known about their natural history. So he just named some of them O. prima, O. secunda, O. tertia, O. quarta, O. quinta, O. sexta, O. septima, O. octava, O. nona, O. decimaO. undecima, and O. duodecima.  When he revised the US species with Steyskal in 1986, he determined O. decima to be a synonym of O. congregata, and he identified some flies reared from asters and goldenrods as O. quinta.

With a number of new specimens at his disposal, Owen made careful comparisons and found that nothing matched the holotype of Ophiomyia quinta. All of the specimens reared from mines like this on Symphyotrichum asters belonged to a new species, which we named Ophiomyia parda because (if you use your imagination) the mines are spotted like a leopard (Panthera pardus). The type series includes specimens I reared from heart-leaved aster (S. cordifolium), smooth aster (S. laeve), panicled aster (S. lanceolatum), and purple-stemmed aster (S. puniceum) collected throughout Massachusetts, plus one from Short’s aster (S. shortii) in Ohio. But Owen chose one from under my solar panel as the holotype. I don’t have a good photo of that specimen, but here is his sister:


As far as I can tell, leaf mines with frass spots like this do not exist on goldenrod or even on other aster genera. The same observation was made by S. W. Frost nearly 100 years ago, and it was his specimens reared from goldenrod that Spencer had identified as O. quinta. Owen examined Ophiomyia specimens I reared from a variety of goldenrods (Solidago spp.), and they all proved to be the very similar species O. maura. Although Owen was unable to examine the US specimens of “O. quinta” that Spencer had examined for his 1986 publication, it seems reasonable to conclude that they were actually a mixture of O. parda and O. maura and that the host and larval habits of O. quinta remain to be determined.

These are just two of the thirty new species described in our new paper. The rest were not found right along my driveway, but a number of them were only a short walk from there. I’ll get to some of those next time…

* Eiseman, Charles S. and Owen Lonsdale. 2018. New state and host records for Agromyzidae (Diptera) in the United States, with the description of thirty new species. Zootaxa  4479:1-156.

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Introducing Phytosciara greylockensis

You know I’ve been way too busy when I let weeks go by without celebrating the publication of a new species description in a BugTracks post. Julia and I spent much of July exploring Michigan and Ontario (including visiting the Canadian National Collection of Insects and attending the combined annual meeting of the Lepidopterists’ Society and Societas Europaea Lepidopterologica), and ever since I’ve been catching up on fieldwork and report-writing, trying to reclaim the parts of our yard that we don’t want to revert to forest, and wrapping up a series of papers on leaf-mining flies I’ve been working on with Owen Lonsdale. Oh, and I spent an intense and thoroughly enjoyable week teaching my Tracks & Sign of Insects… course at the Eagle Hill Institute in Maine. I’ve had to take a break from the leafminer book, but I’m looking forward to getting back on track with that in the coming weeks.

The last book installment I sent out covered all of the monocots except the order Poales (grasses, sedges, rushes, and cattails), and as it happens the July issue of Proceedings of the Entomological Society of Washington included two papers of mine that supplement this chapter. One of them answers the riddle of the agave leaf mines shown in the second half of this post. The other* describes the species of dark-winged fungus gnat (Sciaridae) I showed here. I always like to tell the tale of a species’ first discovery, so here goes…

Back at the 2016 Berkshire BioBlitz on Mt. Greylock, as Julia and I set out on the Rounds Rock trail loop, we passed some bluebead lily (Liliaceae: Clintonia borealis), and I suggested she keep an eye out for leaf mines on this plant.

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Although it was not known to host any leafminers, three years earlier our friend Jesse had spotted some little squiggles on the leaves while we were standing in a parking lot, and ever since I’ve been hoping to encounter some with larvae inside.


Less than a minute had passed when Julia said, “You mean like these?”


Sure enough, she had spotted some mines, but as you can see, they were not like the ones I’d seen before. Rather than being narrow, yellowish lines that meandered freely across the leaf veins, these were transparent, elongate mines that tended to be bounded by the veins. But having already established that nothing was known to mine leaves of this plant, I knew these were worth investigating too, so we spent several minutes filling a big peanut butter jar with leaves containing larvae.


I could see that the larvae were long, narrow, and legless with distinct, brown head capsules, and I thought of Zygoneura calthella, the dark-winged fungus gnat we’d found mining leaves of marsh marigold. Unlike that species, these larvae soon exited their mines and began to window-feed on the lower surfaces of the leaves.


In about a week, they began to gather up bits of leaf and other debris to construct cocoons, which they attached to the undersides of the leaves despite having the option of burrowing into soil.


A few days later, pupae popped out of the cocoons, and out of these popped the adult sciarids.


That last photo shows the single male among the seventeen adults that emerged—but one was enough! I sent the specimens to Kai Heller and Björn Rulik, the same Germans that had helped me with the marsh marigold miners, and their morphological and DNA analysis confirmed that it was a new species—a member of the genus Phytosciara, which has three European species and (until now) none in North America.

I decided to name it Phytosciara greylockensis after the type locality, and not after the host plant, because based on the single collection I didn’t know whether it was specific to Clintonia or a generalist like the two European species whose larvae are known. I have been checking every patch of Clintonia I’ve encountered since 2016, without any further sign of P. greylockensis—until last month, when I found some empty mines near Jason Dombroskie’s cabin in Ontario. So maybe it’s a Clintonia specialist with a northern distribution, and we happened to catch it at its southern range limit on the highest peak in Massachusetts? If anyone else bumps into this species, I’d love to hear about it!

* Eiseman, Charles S., Kai Heller, and Björn Rulik. 2018. A new dark-winged fungus gnat (Diptera: Sciaridae) mining leaves of Clintonia borealis (Aiton) Raf. (Liliaceae). Proceedings of the Entomological Society of Washington 120(3):500-507.

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Fellow Leaf Mine Enthusiasts

The other day I went out to pick some spinach for breakfast, and I noticed this fly resting on one of the leaves:


This is a lauxaniid fly in the Minettia obscura species group, which I recognize mostly by the orange-tinted wings. I often see them resting on leaves, but they usually only let me get one imperfect photo before flying away. This one clung steadfastly to the leaf even after I picked it and continued to fill my hand with other spinach leaves. As I was walking back to the house, it wandered away from its perch and revealed that it had been sitting on this leaf mine, which was small enough to be obscured by its body:


This is a very early mine of Pegomya hyoscyami (Anthomyiidae), another fly. The larvae would devour the entire leaf within a few days if I let them, but as long as we eat spinach regularly we’re able to stay ahead of these flies for the most part (and the occasional leaves that become too infested for us to want to eat go to the chickens instead). Anyway, the lauxaniid moved to the underside of the leaf and proceeded to probe the Pegomya eggs with its mouthparts.


It continued to do this even as I walked inside, set down the rest of the spinach leaves in the kitchen, and placed the fly’s leaf on my desk to take these photos. (By the way, all the tiny spheres on the leaf are calcium oxalate crystals that originate from the leaf’s stomata salt bladders—see Eric LoPresti’s comment below.)


As you can see, by the time I started taking pictures it had stepped away from the eggs a bit, but still showed no interest in abandoning the leaf. Finally, I took the leaf back outside and had to blow on the fly as hard as I could about five times before it finally decided to take off.

As I’ve mentioned previously, the larvae of some lauxaniids (including some Minettia species) are leafminers in decaying leaves on the ground. Others feed externally on decaying plant matter. I suppose this one was attracted to the compromised tissue where the Pegomya larvae had begun to mine the leaf, but it seemed odd that it was so unwilling to leave this leaf behind.

Yesterday I went for a walk in the woods and spotted one of the mystery leafminers I’ve been trying to rear for the past few yearsan unknown scathophagid fly on painted trillium (Melanthiaceae: Trillium undulatum).


I had never encountered this phenomenon before, but just three days later, here was another lauxaniid sitting on a leaf mine! I believe it was another Minettia, though not in the obscura group.

I didn’t have my good camera/lens with me, but the fly obligingly sat there while I took several photos until I’d gotten the best shot I could with the camera I had.


It stayed on the leaf after I picked it, departing only after I rolled the leaf up and slipped it into a rearing vial.

So what’s going on here? It’s tempting to think these flies are laying eggs on or in the leaf mines and their larvae will develop as secondary invaders in the mines, maybe after the original miners have left. For that to be the case, of course, both of these flies would have to be females, and I’m not familiar enough with these to be able to tell from the photos. Naturally, I ate the spinach leaf and destroyed whatever evidence might have been there, but I suppose I’ll hang onto the trillium leaf for a while after the scathophagid larvae exit it and see if any lauxaniid larvae appear.

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Portraits of a Sedge Muncher

I haven’t been going for many walks with a camera lately. I spend so much time viewing the world through various lenses and screens that it’s refreshing to experience it through my own bleary eyes from time to time. But the other day I spotted a Calligrapha beetle on our mulberry tree, and it was sufficiently fancy that I had to dash inside to get my camera. Once I finished with the beetle and was already outside with my big old macro lens, I figured I might as well take a quick stroll through our woods and see what else I could find.

What I found was a furry Ctenucha virginica caterpillar munching on the tip of a sedge leaf (Cyperaceae: Carex). It was just small enough to fit comfortably within the 2-cm field of view of the MP-E 65mm.


I didn’t notice as I was taking the above photo that there are a few little green crumbs of sedge leaf on the left side of the caterpillar’s face. You can also see, in this photo and in the two below, the tiny barbs on each of its hairs, as well as the serrations on the margins of the sedge leaf that give it its rough texture. But what really caught my attention as I zoomed in was the structure of the caterpillar’s prolegs that grasped either side of the leaf.


The curved, translucent structure, I just learned, is called the “planta,” and the tiny gripping hooks that come out of it are called “crochets” (as in crochet hooks). Virtually all butterfly and moth larvae have these hooks, even leafminers that don’t have anything that looks like legs, and this is an important feature in distinguishing them from sawfly larvae.

Ctenucha virginica, by the way, grows up to be a kind of tiger moth (Erebidae: Arctiini) called (get this) the Virginia Ctenucha. Apparently I haven’t photographed one in well over a decade, but they are distinctive day-flying moths that visit flowers, so they’re not hard to find. Here’s one sipping some Queen Anne’s lace.


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In Search of Spring Beauties

Although spring is technically already half over, it only really got started around here in the past week or so. Yesterday I saw my first spring beauties (Montiaceae: Claytonia caroliniana):


These little wildflowers are only around for a few weeks before they disappear along with their leaves, as do trout lilies, wild leeks, Dutchman’s breeches, and squirrelcorn. It’s striking how few of the spring wildflowers host any leafminersnot just these true “ephemerals,” but even many with persistent leaves: bloodroot, wild ginger, blue cohosh, early meadow rue, starflower, and goldthread are all entirely lacking in miners.

So I was excited to find some mines on spring beauty three years ago (May 17, 2015) during a walk in Marshfield, Vermont:


Here’s a backlit view of a different leaf, showing a larva feeding at the tip:


A look at the undersides of the leaves revealed tiny white eggs at the beginnings of the mines:


There are two eggs in the above photo, one of them unhatched. If you think they’re hard to spot, try finding them on a life-sized leaf! Here’s a closer view of a hatched one, next to a bit of pollen:


They were so tiny that I failed to recognize them as eggs of Pegomya (Anthomyiidae)the genus that includes the flies that are already ovipositing in earnest on the spinach in our hoop houseand mistook them for Scaptomyza (Drosophilidae). As a result, after collecting them I didn’t provide the larvae with soil to burrow into, which is generally necessary when rearing anthomyiids. They began to pupate within two days, and although I had collected many larvae, I only ended up with one adult (on June 11):


As discussed in my paper on leaf-mining muscoid flies that was published earlier this year*, this was a female, and a male would be needed to identify the species with certainty. I sent it to Brad Sinclair at the Canadian National Collection and he said it might be Pegomya flavifrons, but he noted that it was dark compared with the much more yellow specimens of that species in the CNC. Pegomya flavifrons normally feeds on plants in the pink family (Caryophyllaceae). Here is one I reared from mouse-ear chickweed (Cerastium fontanum) in Maine:


Although this P. flavifrons is a darker gray, it does have a lot more yellow on its abdomen and face.

So this spring I’m hoping to find more larvae and rear some males to get a definite answer. However, I rarely encounter spring beauty where I live, and I have only seen mines on it that one time, so I’m hoping this post will inspire some of you to keep an eye out for them. If you find any larvae, please either try and raise them, or pass them along to me, or at least tell me where you found them!

* Eiseman, Charles S. 2018. New rearing records for muscoid leafminers (Diptera: Anthomyiidae, Scathophagidae) in the United States. Proceedings of the Entomological Society of Washington 120(1):25-50.

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Spring Sparkler

Happy spring! You may be wondering where I’ve been for the past few months, unless of course you’ve subscribed to the monthly leafminer book installments, in which case you know I’ve been busy putting together a 383-page illustrated introduction, complete with overviews of all of the known groups of North American leaf-mining insects and their predators and parasitoids. The moth chapter in particular was a major undertaking—it turns out that leafmining has been documented in 40 families of Lepidoptera, with one in every ten described species mining leaves for at least part of its larval development.

From here on out, I’ll mostly be adding illustrations and making minor edits to the keys and species accounts I’ve already written. Having reached this milestone, on April 1 I decided it was safe to take all of the overwintering bugs out of the fridge. Three days later, the first adult emerged: Dyseriocrania griseocapitella (Eriocraniidae), which for reasons unknown to me someone has decided to call the “Chinquapin Leaf-miner Moth.” Okay, it’s one of just two leaf-mining moths that have been specifically recorded from chinquapin (Fagaceae: Castanea pumila), but if anyone did some looking I’m sure they’d find that some of the other 15 moths known to mine Castanea leaves can also be found on that species. Larvae of D. griseocapitella are much more commonly found mining leaves of various oaks… along with at least 130 other North American insects. I do think the common name for the family Eriocraniidae, “sparkling archaic sun moths,” has a nice ring to it though.

Anyway, here is one of the mines, collected nearly a year ago, shortly after the oak leaves had opened:


Two days after the leaves were plucked, three larvae exited their mines and I gave them a jar of soil to burrow into.


On my rearing page I noted that after overwintering, “Because I’m worried about moths rubbing off their scales in plastic bags, when I have a baby food jar with soil containing eriocraniid larvae, I take the lid off of it and put it in an upside-down peanut butter jar.” Today when I spotted the moth in the jar, I had the presence of mind to take a picture to show what I mean:


That dark spot at the top of the inverted jar is the moth—here’s a closer look:


The position of the flash heads makes a big difference in the appearance of the sparkly wings.


Although I like the second one best, the occasional purple scales in the third one are pretty nice.


And, just so we’ve got every angle covered:


So, it’s clear where the “sparkling” in “sparkling archaic sun moths” comes from. The “archaic” refers to Eriocraniidae being one of the most “primitive” lineages of moths. An interesting feature shared by the three most “primitive” families—Micropterigidae, Eriocraniidae, and Acanthopteroctetidae—is that the pupa has free antennae and legs as well as functional mandibles, which it uses to wriggle its way to the soil surface so that the adult can emerge. Remembering this, I hunted around a bit and was able to find the pupal exuviae poking out of the soil.


As for the “sun” part, these moths are diurnal, as illustrated by this excerpt from an email sent to me in January by the British dipterist Michael Ackland after I sent him the first installment of the book (as thanks for all his help identifying anthomyiid flies):

The leaf-mining microlepidoptera will be very exciting with the leaf mines and adults very well photographed. My first interest in insects was when I was about 14 when I collected microlepidoptera. I recollect collecting those primitive purple moths around birch during the war (1941). It was on a golf course near Bristol and a German bomber was somewhere overhead. They tried to make daylight raids on Filton, a nearby wartime aerodrome.

Those purple moths on birch would have been Eriocrania semipurpurella, which also occurs here in Massachusetts but I’ve been unable to rear it so far. Maybe this time around…

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