An Underexplored Microhabitat

Although most of what used to be my lawn is now an untamed meadow interspersed with gardens, fruit trees, and berry bushes, once a month or so I do break out the ol’ battery-powered lawnmower to maintain a network of trails through it all. On June 11, which was one of those rare occasions, I paused my mowing and flipped over the mower to scrape out the wads of vegetation that were starting to choke up the blades. I was surprised to find a fly puparium, which I at first interpreted to have been something I had run over with the mower that had miraculously made it past the spinning blades intact.

When I found a second one just like it, I realized that these were puparia from larvae that had developed in the decomposing vegetation that I had failed to scrape off the mower after I had finished my previous mowing session. They looked similar to Anthomyiidae puparia—some anthomyiids are leafminers, but others feed on a variety of other things including decomposing vegetation—but they could have belonged to some other related family.

As I continued to dig through that crud, I found this bristly thing, which I believe to be the puparium of a lesser house fly (Fanniidae: Fannia canicularis)…

…as well as a bunch of larvae like this one:

The fact that this larva has a distinct little head capsule tells us that it’s not one of the so-called “higher” flies, like anthomyiids and fanniids, that form puparia (i.e., they pupate inside the hardened skin of the larva, which the adult ultimately escapes by inflating a big balloon from its face). It’s something more along the lines of a midge or crane fly that forms a naked, exposed pupa.

Naturally, I stuffed a chunk of this rotting plant matter, including these larvae and puparia, into a vial to see what they would all turn into. When I checked the vial on June 23 I found about a zillion of these inside:

This is Coboldia fuscipes, a member of the family Scatopsidae, which are known as the “black scavenger flies.” It belongs to the same group of “lower” flies (Bibionomorpha) as the gall midges, fungus gnats, March flies, and wood gnats, and it is the adult that goes with the larva in the previous photo. Nothing ever emerged from the puparia in the first two photos, but it turned out there was a third species of puparium-forming fly in the mix. Two females of Drosophila busckii (Drosophilidae) emerged, also on June 23, and I was able to find one of their empty puparia.

So, not quite the 30+ species of arthropods I found in a cubic foot of my lawn, but I think four species of flies in a handful of decomposing lawn isn’t too shabby either!

Thanks to Brad Sinclair for identifying the adult flies.

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Oak Shotholes

At the moment there are 648 observations on iNaturalist purporting to show the “oak shothole leafminer” (Agromyzidae: Japanagromyza viridula). Apparently I have personally verified 93 of them, in almost all cases based on the presence of leaf mines. Virtually all the rest are just photos of holes in oak leaves, many of which probably were made by this fly, but in most cases there is no way to tell for sure. I wrote about this species last year, and for your convenience I’ll copy and paste the relevant portion here:

This fly is called the “oak shothole leafminer” because of the holes that open up in the leaves as a result of feeding by adult females. They use their ovipositors to stab the young leaf and then turn around to drink the juices from the wounds. As the leaf continues to expand, a hole opens around a tiny necrotic disc that forms around each puncture (upper right in the photo below). Holes also open up around eggs that are inserted in the leaf (lower left).


In this closer crop you can see the tiny white (because it’s backlit) puncture from the ovipositor near the right edge of the necrotic disc.


There are often multiple holes per leaf. Eventually the necrotic discs drop out, leaving just the “shotholes” as evidence.


Japanagromyza viridula seems to have just one generation per year, but unlike most agromyzid flies with this type of life cycle, adults emerge within a few weeks after the larvae exit their mines, rather than the following spring.


(End quote.)

So, just to be clear, these holes do open at the beginnings of leaf mines of this species (as in the left side of the first photo above), but most of the holes are just caused by the females stabbing the leaves and they have nothing to do with leaf mines. I’ve done my best to discourage folks from adding pictures of holes in leaves without any associated leaf mines to my iNaturalist “Leafminers of North America” project, and early on I left comments pointing out that these holes can be made by other things, but I gave up due to the sheer volume, so take that distribution map with a grain of salt!

Anyway, back on May 25 I noticed this holey leaf on one of the little red oak saplings I haven’t had the heart to mow in the unkempt meadow that is my yard:

If I posted this photo to iNaturalist, it would probably become elevated to a “Research Grade” observation of Japanagromyza viridula within minutes. The thing is, though, when I flipped the leaf over, I found that all of the holes had been made by three little sawfly larvae:

These oak-feeding sawfly larvae with forked spines belong the the genus Periclista (Tenthredinidae). This is the first time I’ve ever seen them in my yard and I don’t know if there’s any way to tell what species they are without rearing them to adults, which don’t emerge until the following spring. So far I’ve reared three different species from oak elsewhere in Massachusetts, and the larvae did show some differences in the head pattern; if those differences are significant, then the ones in my yard might be P. albicollis, which looks like this as an adult:

(Incidentally, when I tried uploading the photo of the holey leaf to iNaturalist just now, the machine learning auto-ID feature told me it was “pretty sure” my photo depicted the work of some kind of chrysomelid leaf beetle; all of its “top suggestions” were likewise leaf beetles and it made no mention of agromyzid flies. Still wrong, but at least it doesn’t think all holes in oak leaves indicate “oak shothole leafminer” as some human observers do. Is my Tracks & Sign of Insects book partly to blame for this perception? Probably.)

I’d be remiss if I didn’t mention that the first photo of the sawfly larvae above also shows galls caused by an undescribed species of midge in the genus Contarinia (Cecidomyiidae), another thing I hadn’t found in my yard before. Just let the squirrels and blue jays plant a few acorns in your yard and your local biodiversity will skyrocket! Another leaf on that same sapling had some different sawfly larvae (Pergidae: Acordulecera) munching on the edge of it.

No way to put a species name on those even if I did rear them to adults; they would pretty likely turn out to be something in the Acordulecera dorsalis complex, which no one has yet tried to sort out. We know so little about some of the most common bugs around us.

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And we’re back!

It’s been just over four months since I last posted here, and I’ve got a few updates to share.

First of all, I’m alive and well; it’s just been an extremely busy field season! In contrast with last year, when I was minimally employed for a good chunk of the time and got to devote many hours to chronicling the goings-on in my yard, this year I’ve been working nonstop in various places that were mostly 1-2 hours from home. Things have finally slowed down in the past couple of weeks, and soon I’ll start going through all my photos from the past half a year and posting the highlights here.

Second, I just finished putting together my fourth annual Leafminers of North America calendar, and as with last year, I will send a copy to anyone who makes a donation of at least $30 (the amount WordPress charges me each year to keep this blog free of annoying ads) before the end of November, which you can do here (select “Send,” and then include your mailing address in the notes). This year each month shows a whole leafminer life cycle instead of a single full-page photo per month.

Third, today the much-anticipated July issue of Proceedings of the Entomological Society of Washington was finally published, and it includes a short paper of mine* that relates to two things I’ve written about here previously. In June 2018, I wrote about two lauxaniid flies in the genus Minettia I had recently met that seemed very interested in leaves that were being mined by other flies. In my concluding paragraph I wrote, “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.” In June 2019, when I announced the completion of the first edition of Leafminers of North America, I mentioned that I had just been on a successful mission to collect more larvae of a Calycomyza species that appears only in early June, has only been found at a single location, and is so far known only from unidentifiable females, but almost certainly represents a new species. Well, I did manage to rear some more adults of that Calycomyza, including a single male (which Owen Lonsdale hasn’t yet had a chance to examine), but a couple of weeks after the last Calycomyza larva had exited its mine and pupated, a different kind of fly larva emerged from one of the now decomposing leaves:

I didn’t get around to photographing this larva’s puparium until the following spring (which is to say, spring of 2020), when the adult fly emerged:

Under magnification, I could see that the puparium was covered with the calcareous secretion that lauxaniid puparia have been described as having, and the adult proved to be a Minettia, the same genus I had suspected of sometimes developing in abandoned mines of other flies!

One of my manuscript’s reviewers, at least, thought that was pretty exciting.

And finally, although I haven’t had time to write any BugTracks posts in recent memory, I have been faithfully posting a photo of a different species from my yard on Twitter every day since October 14, 2020. If you’re so inclined, I think you can scroll through those photos whether or not you have a Twitter account. The first 250 are here, the second batch is here, and I recently started a third thread after the first year was up. In other spare moments while at my computer, I’ve been making my way through the backlog of observations in the “Leafminers of North America” iNaturalist project, where I’m currently up to August 3, with 7360 observations left to go. I’ve been sharing some highlights in another Twitter thread.

That’s all for now, but more coming (relatively) soon!

* Eiseman, Charles S. 2021. Minettia Robineau-Desvoidy spp. (Diptera: Lauxaniidae) as secondary invaders in leaf mines of other insects. Proceedings of the Entomological Society of Washington 123(3): 669–672.

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Leafminers For All!

Two years and two weeks ago, I announced the completion of the first edition of my Leafminers of North America e-book.

It’s been gratifying to see more and more people all across North America looking for leaf mines, successfully using the keys in my book to identify what they’ve found, and documenting new host and distribution records as well as previously unknown mines in the iNaturalist project I created.

But some of the most enthusiastic leaf mine hunters don’t have my book, and I have no doubt that the $90 price is a barrier to some. So I’ve decided to make the first edition available on a sliding scale. To get access to the full first edition, all you have to do is use this link to send a payment of any amount ($5 or more), entering “leafminer book” in the “Add a note” field, along with the email address where you’d like to receive the link.

Or you can become a patron at $5 a month, and you’ll get the whole first edition right away as well as start receiving the second edition in monthly installments.

Anyone who contributes (or has already contributed) $90, either all at once or cumulatively, gets a lifetime subscription to updates. I’m about halfway through releasing the second edition, and the portion I’ve done is already more than 200 pages longer than the corresponding portion of the first edition. In addition to new host and distribution records and previously unknown mines, I’ve been adding photos of adults and mines for species that weren’t illustrated previously; names of newly described species; new natural history information from recently published papers; and other new observations that haven’t yet been reported in peer-reviewed literature.

The new discoveries are showing no sign of slowing down, so I expect to start in on the third edition soon after I finish the second. The latest came the day before yesterday: while conducting a botanical inventory in Southborough, MA, I spotted a leaf mine on a young grapevine that I recognized right away as something never before documented on grape.

Here’s the same mine a few hours later, after I got it home and had access to a better camera:

Everything about this mine, including the two yellow larvae feeding side by side, is consistent with Orchestomerus eisemani, heretofore known as a Virginia creeper specialist. Adults of the other eastern Orchestomerus species, O. marionis, have been collected on grape, but if that species were a leafminer I would think someone would have noticed its mines before now. I’m betting this is O. eisemani trying out a new host, a hunch supported by the presence of several vacated mines on Virginia creeper a few meters away—which, incidentally, is the first evidence of this species in Worcester County, a slight extension of its known range. It’s the next county over from my own, albeit way over at the other end. I wonder how long I’ll have to wait to see O. eisemani in my own yard.

Yesterday morning the larvae had extended their mine considerably, still feeding side by side…

…and overnight they popped out and burrowed into the soil at the bottom of the jar I had placed the leaf in. With any luck, they’ll emerge as adults in a few weeks and I’ll be able to confirm their identity.

I may or may not get around to reporting the result here, but you can be sure it will make an appearance in the third edition of Leafminers of North America!

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One Weird Inchworm

This morning I had a look around my yard after being away for the past week, and I met this fantastic creature on a leaf of one of our cultivated hazelnuts:

Its body was awkwardly contorted, and it took me a lot of tries to get a photo with all (or most) of it in focus.

When it started walking around, I was surprised to see that it was able to unfurl those tendril-like appendages (even harder to get in focus when it was in motion, but these photos will give you some idea).

This strange beast is a horned spanworm (Geometridae: Nematocampa resistaria), something I’ve encountered only a couple of times before, and this one was the largest and fanciest. Here’s a very young one I found on a black cherry leaf on 6/13/2013:

And one found on a woodland sunflower, 6/8/2019:

Although today’s larva was the first I’d seen in my yard, I spotted an adult of this species on the basement ceiling on 7/6/2014:

The caterpillar seems like something that belongs in the tropics, and sure enough, here’s a video showing a Nematocampa larva in action in a Peruvian rainforest:

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More and more

Adults have emerged from another 20 or so overwintered vials and jars since my previous post. Here are some more that came from larvae collected right in my yard.

On June 21, I collected these larvae from one of our cultivated hazelnuts (Sawfly #27 in this post):


Thirteen of them reached maturity and burrowed into a jar of soil by the end of the month. Over the past few days, three of these wasps have emerged from the soil:

They appear to be braconids in the genus Ichneutes (thanks to Gergely Várkonyi for the ID). In my decade of rearing all sorts of herbivorous insects, to my knowledge I have only previously reared two braconids in the subfamily Ichneutinae, both from tiny leaf-mining moths. The ichneutines that parasitize sawfly larvae oviposit in their hosts’ eggs, or sometimes in young larvae, but their offspring wait until the sawfly larvae have finished feeding and spun their cocoons before doing most of their own feeding and ultimately killing their hosts. Did the mother Ichneutes manage to insert an egg into every one of these hazelnut larvae (or the eggs from which they hatched) before I got to them? Time will tell.

Last year’s Leafminer #89 was Stigmella prunifoliella (Nepticulidae), which I identified based on a predated leaf mine on black cherry that I found on June 26. On September 28 I collected a few leaf mines on peach that I presumed were the work of this species, but I wanted to make sure since it hadn’t been documented on peach before. Here is a very early mine, with the green larva munching away inside…

…and here is a vacated mine three days later…

…and here is the adult that emerged on March 22:

Virtually all of the insects I have emerging right now are univoltine species, with just one generation per year, and larvae found only in spring or early summer. With the exception of some parasitoid wasps, Stigmella prunifoliella is the only multivoltine species that has made an appearance so far.

Last year’s Sawfly #25 was a larva I found in June on white avens (Rosaceae: Geum canadense)…


…and within a few days I found larvae that I thought might be the same (though I noted a behavioral difference), feeding on leaves of cultivated strawberries.


On March 22, an adult emerged from each jar—strawberry…

…and avens:

I still think they might be the same! I believe the only sawfly in North America with free-living larvae that have been found on avens is Pristiphora pallidiventris, and this clearly isn’t that. I’m guessing this is one of the six species of Allantus, Empria, and Taxonus that are known to feed on strawberry, but I won’t worry about which species that might be just yet. [Edit, 3/26/2021: Marko Prous says these are “Empria (maculata maybe, which seems to be a complex of several species)”.]

Early last June I pointed out a gall on a fox grape leaf made by Heliozela aesella (Heliozelidae), an odd species in a family that (in North America, anyway) is otherwise composed of leafminers. Here is a better look at one of the galls, viewed from above and below:

The mature larva cuts out an oval chunk from the upper surface of the gall and wraps it around a tube of frass held together with silk, then wanders off, dragging this portable burrito-house until it finds a suitable place to overwinter, at which point the gall chunk becomes its cocoon.

On March 22 two of these emerged as adults:

While I was putting together my “Bugs in Winter” course, I cut open some goldenrod stem galls from my yard so I could include photos of their interiors in one of my slideshows. When I cut open this gall of Epiblema scudderiana (Tortricidae) in January…

…I found the live moth larva still inside (as would be expected for this species), visible in the photo below through a little nick in its protective silken tube.

Since it would likely be doomed if I put the opened gall back outside, I instead put the gall in the fridge along with the other overwintering bugs, and took it back out with the rest of them on March 1. Alas, it turned out the larva had already been doomed by parasitoid larvae living inside it: eleven of these microgastrine braconid wasps emerged on March 22:

Based on this study of parasitoids of Epiblema scudderiana, these wasps might be Apanteles cacoeciae, which was the only microgastrine and the only gregarious parasitoid associated with this moth in western Pennsylvania.

Back on May 29, I found my second type of sawfly larva for the year, a member of the Acordulecera dorsalis complex (Pergidae) feeding on red oak.


The seven larvae I collected all burrowed into soil by June 3, and three adults emerged on March 23 and 24.

All the ones from my yard, and another five I reared from a red oak sapling across the road, look like the one above—not as fancy as the ones I reared from the same host in Connecticut five years ago:


And finally, there was the leaf-rolling sawfly larva (Pamphiliidae) that I found on June 7 on one of the shadbushes we planted by our garage:


The adult emerged yesterday, a lovely wasplike creature:

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First sawflies of the season!

I took all my overwintering larvae and pupae out of the fridge on March 1, and so far two agromyzid flies, two scathophagid flies, two braconid wasps, two eulophid wasps, and seven sawflies have emerged as adults. Apart from the braconid and eulophid parasitoids, these are all species that have a single generation per year, with larvae that are only active for a few weeks in spring or early summer, so every individual that emerges nearly a year later feels like a major triumph.

The first sawfly appeared on March 12, from a jar of soil into which at least seven larvae had burrowed between June 18 and July 11 of last year. I had collected three larvae on June 13 from some field horsetails (Equisetaceae: Equisetum arvense) in the ditch across the road from my house, and several additional larvae appeared in the jar over the next couple of weeks—they had been either eggs or tiny larvae that I didn’t notice when I collected the three larger larvae. Here’s what one of them looked like on June 15:

And one on June 18:

This winter, between putting together my “Bugs in Winter” online course, revising portions of Leafminers of North America, peer-reviewing hundreds of pages of manuscripts written by other leafminer researchers, and getting a few papers of my own ready to submit, I managed to make reasonable progress on my guide to sawfly larvae, including writing the section on horsetails. What I learned as I put together the horsetail section is that Leblanc & Goulet (1992) published a key to larvae they had raised from eggs laid by six species of Dolerus (Tenthredinidae) they had collected in eastern Canada and put in cages with field horsetail plants. Twenty other Dolerus species and subspecies in North America are likely to feed on horsetails because they belong to subgenera that have been exclusively associated with horsetails in North America and Europe (mostly as caught adults), but the larvae are completely unknown for all of these. So as far as I know, this adult that emerged four days ago is the first North American horsetail-feeding sawfly that anyone has actually reared from larva to adult:

I haven’t made any attempt to identify it yet, but the larvae don’t match any of the six species described by Leblanc & Goulet, so it seems like some progress has been made here. I think they are the same as sawfly #19 from last year’s yard list, which was likewise found on field horsetail, and I think they’re also the same as the larvae I found on wood horsetail (E. sylvaticum) by the beaver pond down the hill from my house—an adult emerged from that jar today, but I haven’t had a chance to photograph it yet.

I fully expected the first sawfly adults to emerge to be Dolerus, since I’ve seen adults of this genus as early as March under natural conditions. I also expected that other early emergences would include some of the first larvae I found last year. On May 31, I collected five larvae like this from a little aspen sapling in my front yard (sawfly #3 from the yard list):


At the time the sapling was unambiguously a bigtooth aspen (Salicaceae: Populus grandidentata), but over the course of the summer it transformed into an unambiguous quaking aspen (P. tremuloides). I haven’t yet attempted to make any sense of the 20+ North American sawfly species that are known to feed on Populus, but as I mentioned when I first found these larvae, I suspect the genus is either Euura or Nematus. Whatever species this may be, I now know what the adults look like, because all five of them emerged on March 14 and 15.

Sawflies overwinter as larvae in their cocoons, waiting until spring to pupate. So apparently these two species can be convinced that spring has arrived after being exposed to warmer temperatures, then pupate, transform to adults, chew their way out of their cocoons, and claw their way to the soil surface, all in the space of 11 to 14 days.

With any luck, there will be more updates soon!

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Introducing Haplopeodes loprestii

This leafminer business all started nearly ten years ago, in the fall of 2011. I had become fascinated with these tiny creatures while I was writing Tracks & Sign of Insects and Other Invertebrates a few years earlier, but it was after visiting Nantucket for the first time, from September 7 to 11 of that year, that I decided to embark on a quixotic quest to create a complete guide to the leafminers of North America, so that I could fully identify everything that I had found there.

During that visit, I met an enthusiastic intern at the Maria Mitchell Association named Eric LoPresti. It was when I returned in November to present my findings at the Nantucket Biodiversity Initiative’s biennial research conference that I met his fellow intern Julia Blyth (now the museum’s consulting collections manager), who has joined me in all my subsequent surveys of the island, as well as on leafminer expeditions all over North America.

In October 2012, in the middle of a three-month voyage around the US, Julia and I explored northern California with Eric for a few days during his first year as a grad student at UC-Davis. In 2017, toward the end of his time there, he invited us out to play in the desert super bloom in southern California, and we spent a week leafminer-hunting with him there and in Arizona. Eric has a knack for finding interesting new mines, and once I tell him something is interesting, he keeps bringing me more and more of it until I have to tell him to stop. One day we discovered previously undocumented leaf mines on sand verbena (Nyctaginaceae: Abronia), a plant for which he has undying enthusiasm, and I thought it would be perfect to name the species after him if I managed to rear it.

I did manage to rear it, but it turned out just to be a new host family for the well-known and extremely polyphagous species Liriomyza trifolii (Agromyzidae).

Later, Eric gave me some leaf mines on Fagonia laevis (Zygophyllaceae), a small-leaved desert plant related to creosote bush. No leafminers were known to feed on this plant, so I was excited to see what the larvae would turn out to be.

They were clearly moth larvae, but to say anything more specific I would have to rear them…

…which I succeeded in doing, but they turned out to be some kind of Gelechiidae in the tribe Gnorimoschemini, a particularly difficult group, so I’ll need to enlist a specialist to figure out what they are more specifically.

But in the meantime, two tiny fly puparia had appeared in the rearing container, and I segregated them out to see what would emerge from them.

Two months later, this female fly appeared…

…and two weeks after that, this male:

Were these weird-looking things agromyzids? I wasn’t sure, but it seemed like they might be, so I threw them in with a big batch of agromyzids I sent to Owen Lonsdale, and when he got a look at them, he reported that they were a new species of Haplopeodes. This is an agromyzid genus I’d never met in person before; in North America there are just four other known species, which are leafminers of Amaranthaceae, Portulacaceae, and Solanaceae and are not known to occur in the Northeast.

Unless you skipped past the title of this post, you won’t be surprised to learn that Owen and I named the new species Haplopeodes loprestii, in a paper that was published this week*. The other twelve species described in this paper were reared by our three coauthors: John van der Linden, Tracy Feldman, and Mike Palmer. Coincidentally, last fall Eric moved to Oklahoma, where he is now an assistant professor at Oklahoma State University, filling the position that became available when Mike Palmer retired and moved to Oregon.

So what does Haplopeodes loprestii do for a living? It’s probably a leafminer, since all its known relatives are, but since the rearing container included Fagonia stems and fruits as well as leaves, it’s conceivable that the larvae feed in one of these other structures. The leaves are so small that if there were two different types of mines in them, it would have been hard to notice—and I didn’t know to look until the leaves were too far gone to try. Always more to learn!

* Eiseman, Charles S., Owen Lonsdale, John van der Linden, Tracy S. Feldman, and Michael W. Palmer. 2021. Thirteen new species of Agromyzidae (Diptera) from the United States, with new host and distribution records for 32 additional species. Zootaxa 4931(1): 1–68.

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A couple of quick end-of-year announcements:

The online “Bugs in Winter” course I mentioned a few weeks ago is now full, because a limited number of people can participate in the live discussion sessions. However, the course content is now also available as an “on-demand” purchase; the only difference for people doing it this way is that they won’t be able to tune in to the live sessions (but they will still be able to watch recordings of them afterwards). As always, I will be available to answer any questions by email. For more information about the course, see this page.

The other, and more time-sensitive, announcement is that I’ve got some 2021 Leafminers of North America wall calendars available. These are normally reserved for my most generous patrons, but I will send one to anyone in the US or Canada who makes a contribution of $30 or more by midnight today (eastern time). $30 is the price I pay WordPress each year to keep this blog free of ads, so not a bad deal if you ask me! To make a contribution of any amount—which will go to support my continuing research into leafminers, sawfly larvae, and other obscure but fascinating herbivorous insects—you can use this link.

This year’s calendar includes some photos of leaf mines and some photos of adult insects I’ve reared from them. The cover photo (above) shows a white oak leaf with mines of three different moth genera: Stigmella (Nepticulidae), Cameraria, and Phyllonorycter (Gracillariidae).

Thanks everyone for your interest in my natural history ramblings, and I’ll see you next year!

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The Yard List(s), Part 32

As I do every winter, I’ve lately been picking away at organizing all the photos I’ve taken over the past year, and the other day I discovered that this blog’s running list of leafminers in my yard omitted a species I found back in July. It should have been #119 for the year, but we’ll call it…

Leafminer #209: Lyonetia prunifoliella (Lyonetiidae). On the evening of July 8, I collected some fresh pin cherry leaves for my attempted rearing of leafminer #70 (which I believe was Caloptilia invariabilis, but only braconid wasps ever emerged). One of the leaves had this vacated mine on it:

The fecal pellets strung like pearls on a strand of silk, dangling from a hole in the lower epidermis at the edge of the mine, easily identifies this as the work of L. prunifoliella. Young larvae of this species make narrow, linear mines with frass in a dotted central line, but this larva had wandered from its original leaf before establishing this blotch mine. Here’s an adult I reared from a pin cherry leaf I collected while teaching my leafminer course at the Eagle Hill Institute in Maine in the summer of 2019:

Might as well take care of some other loose ends while I’m at it.

Leafminer #210: Ophiomyia euthamiae (Agromyzidae), on grass-leaved goldenrod (Asteraceae: Euthamia graminifolia). This is another species (along with O. parda and Phytomyza erigeronis) that has my front yard as its type locality, and I was watching for it all year until I finally found a few mines at the southeast corner of the yard on October 23. The entire type series was reared from mines I collected in October 2015, so maybe this species just has one generation per year and larvae are only active in the fall, but the adults emerged from those mines three to six weeks after I took them out of the fridge in spring 2016, so one wonders what the adults are doing all summer. I guess it’s possible the eggs are laid in spring and early summer but don’t hatch until the fall, but as with so many things, further investigation is needed to figure out what’s really going on.

This species makes linear mines that are initially on the underside of the leaf…

…but then switch to the upper surface, where the blackish puparium is ultimately formed (upper left in the photo below).

Here’s another example from 10/23/2020:

And here’s the holotype from five years ago:


Once it started getting all snowy I figured that was about the end of this year’s leafminer list, but then on December 14 it occurred to me to check the young conifers at the edge of the woods.

Leafminer #211: Coleotechnites sp. (Gelechiidae), on hemlock (Pinaceae: Tsuga canadensis). There are two species with identical habits, of which one has green larvae (C. apicitripunctella) and the other has brown larvae (C. macleodi). The larva mines in one or two needles in the fall, overwintering in its last mine, and then in the spring it ties together several needles with silk, at first mining in them and later feeding on them externally. I haven’t yet found a larva inside a mine, but here is an abandoned group of tied and mined needles from last spring.

Seven years ago I managed to rear this adult of the brown hemlock needleminer:

Leafminer #212: Argyrotaenia pinatubana (Tortricidae), on white pine (Pinaceae: Pinus strobus). The larva of this species, the “pine tube moth,” ties a bunch of pine needles into a tubular bundle and then mines into several of them. It forms several of these bundles throughout its life, and in the last one, rather than mining the needles, it lines the inside of the tube with silk and then starts cutting off the ends of the needles one by one and then munching on them within the shelter of its tube. As with the hemlock needleminers, I haven’t yet found (or looked for) the young larvae, but the cut-off tubes of mature larvae are a common sight.

I was also keeping track of all the plants I ate in my yard this year, so here’s the final report on those.

123. Foxtail grass (Poaceae: Setaria pumila) – seeds
124. Black birch (Betulaceae: Betula lenta) – twigs (tea)
125. White pine (Pinaceae: Pinus strobus) – leaves (tea)
126. Medlar (Rosaceae: Mespilus/Crataegus germanica) – fruit
127. Arborvitae (Cupressaceae: Thuja occidentalis) – leaves (tea)
128. Lemon (Rutaceae: Citrus × limon) – fruit
129. Poppy (Papveraceae: Papaver somniferum) – seeds
130. Hemlock (Pinaceae: Tsuga canadensis) – leaves (tea)

The 130 plant species I ate belonged to 47 different families, the most important being Asteraceae (14 species), Rosaceae (13 species), and Brassicaceae (10 species). The 212 leafminers (representing 18 moth families, four families each of flies and beetles, and two sawfly families) collectively fed on plants in 52 different families, but no one species was found on more than two plant families. As with me, Asteraceae was the most popular family with the leafminers, supporting 39 species, followed by Rosaceae (35 species), Fagaceae (18 species), and Betulaceae (15 species). The 49 different types of sawfly larvae I found (including both leaf-mining and free-living species) were found on plants in 16 families, with 13 of them on Rosaceae, 11 on Betulaceae, four each on Fagaceae and Salicaceae, and just one on Asteraceae. For whatever that’s worth.

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