Hazelnut Sawflies

It’s normally a little disappointing to find an ichneumon wasp in one of my rearing containers, since that generally means I failed to rear whatever insect I was trying to rear. So when this one appeared yesterday…

…I braced myself for the bad news as I checked the lid of the jar to see what sawfly larva I had collected sometime last year, kept provided with fresh leaves of its host plant, given a jar of soil to burrow into, and refrigerated over the winter, only to have it succumb to a parasitoid, leaving its identity as mysterious to me as if I had just taken a photo of it on the plant and left it to its fate. But I found that what I had scribbled on the lid was “10/1/22 hazelnut, parasitized, gone 10/2.” Which meant that I already knew it was parasitized when I collected it on October 1, and it burrowed into the soil by the next day—so not a big loss, and a minimal investment of effort on my part. As it happens, I had just made it up to October 1 in sorting through the photos I took last year, so I was able to quickly refresh my memory about who this sawfly larva was. But before I get to that, a little background on the hazelnut sawflies in my yard.

Although there are native beaked hazelnuts (Betulaceae: Corylus cornuta) growing wild around the edges of the yard, it is the hazelnuts we planted—Corylus ‘Medium Long’, which is thought to be a hybrid of American hazelnut (C. americana) and the European hazelnut (C. avellana)—that always seem to attract the sawfly larvae. Just about every year, these larvae show up and get to work defoliating them:

Both of the above photos were taken on September 2, 2016, and at the time I thought I was seeing different-aged larvae of the same species—in fact, they were filed together until today, when I realized the smaller larvae in the top photo belong to a different family (Tenthredinidae; tribe Nematini) from the spotted larva, which is in the family Argidae. It was the spotted larvae that I succeeded in rearing; adults emerged the following June, and Dave Smith identified them as Arge willi.

When I did a thorough inventory of the sawfly larvae in my yard in 2020, larvae of the first type showed up on June 21. I collected them but again failed to rear them; four parasitoids in the genus Ichneutes (Braconidae) emerged the following March.

And I found larvae of Arge willi starting on September 1.

Then, on October 10, I found this beauty (which is something in the subfamily Tenthredininae)…

…but I failed to rear it as well. I looked in vain for more larvae like this in October 2021, and then again this past October. Although no yellow-spotted larvae materialized, I did find yet another species that I hadn’t seen in my yard before.

I think these may be Hemichroa crocea, which normally feeds on alder (Alnus) but is occasionally found on birch (Betula) and hazelnut (Corylus). I was just about finished writing my key to birch-feeding sawfly larvae this winter when I turned my attention to a taxonomic paper on tischeriid moths, but hazelnut will be the next key I do when I get back to that project (well, after musclewood (Carpinus), as I work my way alphabetically through the birch family). Anyway, on the same bush as the larvae above, I found this one, which (based on my knowledge of birch-feeding sawflies) I believe is a Nematus species.

I saw the objects attached to its head and thorax and knew it was unlikely to survive, but I decided to collect it anyway. Ichneumon wasps in the subfamily Tryphoninae attach stalked eggs to their hosts, and I think that’s what the brown object on the head is. As for the white object on the thorax, I believe it is a larva rather than an egg, but whether it’s a tryphonine or something else, I’m not sure.

In this view, the stalk on the egg is more apparent:

I think the ichneumonid that emerged yesterday is in fact a tryphonine, but someone please correct me if I’m wrong. And its sawfly host may have been Nematus corylus; for comparison, here are some larvae of that species that Julia and I collected on Nantucket in September 2020…

…and an adult that emerged the following April:

Looking back through my photos, I think N. corylus was probably the host of the braconids, and it may have been the species that I initially mixed up with Arge willi, but I don’t seem to have photos of those larvae in later instars. Once I put together my key to larvae on hazelnut I’ll have a better sense of how many (known) options there are for larvae with that general appearance. In any case, it’s nice to have our hazelnut bushes providing food for at least four different sawfly species, in addition to occasionally giving us some nuts to eat.

A leaf-mining midge odyssey (Part 1)

Back in 2012, when I had only recently realized I needed to write a complete guide to the leafminers of North America and as a result Julia and I were driving around the US to find them all, we visited a friend of mine from college, Josh Lane, in Bonny Doon, California, which is a little south of San Francisco. The three of us took a walk on a drizzly Halloween morning, and the first leaf mines we noticed were on a plant that Josh informed us was yerba santa (Namaceae: Eriodictyon)…

…which made it easy to identify the maker of the mines as Phytomyza eriodictyi, an agromyzid fly.

Apparently it wasn’t a very productive walk, based on the photos I took that day, because it was over a half an hour before I pulled out my camera again, and that was to photograph not a leaf mine but an elaborate web of an orbweaver in the genus Metepeira (Araneidae), consisting of a typical spiraling orb web next to a labyrinth of crisscrossing threads, near the top of which the spider had constructed a retreat out of bits of leaves and other debris, in which it was now waiting for insect prey to become caught in the web.

Fifteen minutes later, we stopped to examine one of California’s zillion species of Ceanothus (Rhamnaceae), which had mines of three different moth families on display.

This elongate mine that caused the leaf margin to curl over and conceal it was made by a Tischeria species (Tischeriidae); a lot more work needs to be done on this group, and if anyone out there is interested in rearing adults and sending them to me, I would love to check them out.

Linear mines on Ceanothus are made by Nepticulidae; I still don’t know how to distinguish mines of Acalyptris punctulata from those of the several Stigmella species on these plants. Another good project for someone.

And then there were the distinctive mines of Xenolechia ceanothiella (Gelechiidae), each consisting of a branching track with a tubular retreat of silk spun just outside the entrance on the lower surface.

A few minutes later we arrived at a seepy spot that I dimly recall as being our destination for this walk—I think Josh wanted to show us this plant, and I don’t remember now if it was because he had noticed mines on it or just because it was a neat plant that was in bloom then, but in any case he evidently didn’t know what it was because in my journal it’s just referred to as “Bonny Doon scroph,” as in, what used to be the snapdragon family (Scrophulariaceae) before most of its species were moved to other families including Orobanchaceae, Phrymaceae, and Plantaginaceae. I later learned that the plant was musk monkeyflower (Phrymaceae: Erythranthe moschata, formerly Mimulus moschatus), which also exists back home in Massachusetts, where it is rare and protected as a Threatened species.

Some of the leaves were riddled with linear mines, which had the general look of fly mines, with grains of frass along the sides, or at least not forming a central line.

Upon picking the leaf in the photo above and flipping it over, I could see a larva inside one of the mines, and it was much more elongate than a typical agromyzid fly larva. It’s at the top center in the photo below.

Looking more closely, it had a definite head capsule, unlike any of the usual leaf-mining fly larvae.

On a nearby leaf, we found a larva in the process of establishing a new mine, lying on the upper surface with just its front end inserted below the epidermis.

These seemed to be midge larvae (Chironomidae), which are normally aquatic, and are not normally leafminers; the only remotely similar phenomenon I was aware of was the mine-like channels that Polypedilum braseniae makes in floating leaves. We speculated that the wet weather had provided the opportunity for these larvae to venture up out of the seep and into normally inaccessible leaves. After spending 15 minutes with this mystery, and sticking a few leaves in a vial with the hope of rearing an adult, we finished our walk, and Julia and I continued on down the California coast.

Three days later, I took this photo of one of the larvae worming around along the wall of the vial…

…And two days after that, I could see a couple of pupae among the leaves in the vial. Here’s one:

And the other, with its shed larval skin (exuviae) visible to the right.

A month later, no adults had emerged, and when writing to Ray Gagné about some of the interesting gall midges we had found on our trip, I asked him if he could suggest anyone who might know about these leaf-mining midges. He referred me to Peter Cranston, who he noted is based in Australia but had spent many years in California. Peter in turn referred me to John Epler as the go-to person for information on Chironomidae in the US, but in Peter’s reply, he wrote:

Was the yellow-flowered scroph a Mimulus by chance ? I have seen grazing like this on leaves essentially in the splash zone but without contents.
There is a diffuse literature on leafmining in chironomids, but most refer to immersed leaves. As for terrestrial leaves there are reports of some orthoclads from Brasilian rainforests, but I do not recall if the observations are formally published and related to an identified taxon. Many years ago I was sent a larvae from Australian rainforest but it may have been developing in a mucous blob rather than truly mining.

John (who lives in Florida) was unfamiliar with this midge, but agreed that it looked like a chironomid and he offered to examine the pupae, instructing me to be sure to preserve the larval exuviae as well. He listed a number of chironomids that do something that might be considered leafmining, but none of them out of the water, and after thoroughly scouring the literature, I have only come up with four species worldwide that have been documented as true miners (living between the two epidermal layers and feeding on the excavated tissue) of living leaves; all of them are in the genus Cricotopus and mine in floating or submerged leaves of pondweeds (Potamogetonaceae: Potamogeton).

After an intensive search of the leaf mush in the vial, I could only find one of the pupae, but I did manage to locate the larval exuviae. When I sent these items to John, he said there was no pupa, just a piece of leaf with a seed stuck to it, but he was able to slide-mount the larval skin and determine that it belonged to the genus Metriocnemus (which is in the subfamily Orthocladiinae, so related to the rumored terrestrial leaf-mining midges from Brazil).

I have not personally encountered a leaf-mining midge since, but five years later (in June 2017) John van der Linden found some midge larvae mining in water speedwell (Plantaginaceae: Veronica anagallis-aquatica) in Iowa. He reared three flies from these leaves, which included Scaptomyza pallida (Drosophilidae)—a species I have reared several times as a secondary inhabitant in mines, leaf rolls, and other damaged plant tissue caused by other insects—along with two midges. John Epler was too busy to examine more specimens at that point, but I asked around and found a midge specialist in Canada, Armin Namayandeh, who was happy to help when John van der Linden wrote to him. Unfortunately, both were females and as a result could not be confidently identified, but Armin reported that both appeared to be in the genus Bryophaenocladius but represented two different species.

Late the following January, John found some more of these Veronica miners and decided to try and rear them again. This time, in addition to the larvae that were making the mines—which looked similar to the ones I had found in California—he noticed a smaller, darker larva moving around in one of the mines, nibbling here and there along the edges; he suspected this was a secondary inhabitant.

He preserved that larva, and Armin determined that it belonged to the genus Limnophyes; he also reexamined the two adult females and realized that they were likewise Limnophyes, based on lanceolate setae on the thorax that he had neglected to note when he first looked at them. John also reared a couple of adult males, which Armin identified as Metriocnemus eurynotus, a species whose larval habits had never been reported.

But back to monkeyflowers: they turn out to be the study organisms of Kathy Toll, the partner of Eric LoPresti, who was an intern at the Nantucket Maria Mitchell Association along with Julia when we first met on Nantucket in the fall of 2011. In June 2019, Kathy found some midge mines on seep monkeyflower (Erythranthe guttata) growing along the California coast, and although I was again unable to rear any adults, I was able to preserve one larva.

Another two years passed, and then in March 2021 Mike Palmer sent me a photo of a leaf mine on seep monkeyflower that he’d just found on his land in Oregon. He had no idea this mine would be of particular interest to me, but he was excited because it was the first mine of any kind he had found there since the Holiday Farm wildfire had devastated the area a few months earlier. He had retired from his position at Oklahoma State University and moved to Oregon full-time, just in time to have his home destroyed and the entire property scorched and covered in ash. The vertical rock face where the monkeyflowers and various other herbaceous plants appeared that spring—along with the leafminers—had been covered by a dense bryophyte layer before the fire.

Two months later, Eric (who had just taken over Mike’s old position at Oklahoma State) and Kathy found some mines on roundleaf monkeyflower (E. glabrata) in Oklahoma.

At last, this time we succeeded in rearing some adults.

I sent them (and associated larval and pupal exuviae) to Armin, along with Kathy’s larva from California, and after comparing them with the description of every other Metriocnemus species in the world, he determined that they represented a new species, which we decided to name M. erythranthei. He borrowed the slide that John Epler had prepared of the larva I had collected back in 2012, and he confirmed that it (like Kathy’s larva) was the same species.

Now that this monkeyflower midge was finally going to get a name, last spring I encouraged Mike to try rearing some so we could be sure that what he had found in Oregon was the same species, and I also encouraged John van der Linden to do some more rearing from water speedwell. Unfortunately the whereabouts of his specimens mentioned above is currently unknown; Armin moved from Ontario to Michigan in the intervening years and hasn’t been able to relocate them so far. Both Mike and John were successful, and then some: even though Mike didn’t yet have a lab setup or even a permanent living space, he managed to rear a bunch of adults from monkeyflower almost immediately, and he also collected larvae and pupae, and reared a few adults, from a number of different plants on that same seepy rockface: Siberian spring beauty (Montiaceae: Claytonia sibirica), forget-me-not (Boraginaceae: Myosotis scorpioides), Arctic sweet coltsfoot (Asteraceae: Petasites frigidus), coastal hedgenettle (Lamiaceae: Stachys chamissonis var. cooleyae), and mint (Lamiaceae: Mentha × piperita ssp. citrata)—not to mention from Veronica americana, the native relative of water speedwell, at a nearby site. John reared more adults from water speedwell, and at the same site in Iowa found different-looking midge larvae mining in jewelweed (Balsaminaceae: Impatiens) cotyledons. Just to make things extra confusing, he also found some of these larvae feeding inside the Metriocnemus mines on water speedwell:

Meanwhile, with the exponential growth in popularity of documenting leaf mines on iNaturalist, observations of these midge mines started popping up all over the place, and I got several people to collect specimens for Armin to examine: Finn McGhee collected a pupa from seep monkeyflower in British Columbia; Jeff Ward reared a female from Siberian spring beauty in Oregon; and Cecil Smith collected larvae from water speedwell in Pennsylvania.

The verdict? The miners in monkeyflowers and speedwells from the west coast to Pennsylvania are all the same new species, Metriocnemus erythranthei. South and east of Oregon, there is no evidence of this midge feeding on any other plants, but in Oregon it mines in Siberian spring beauty and all those other plants from which Mike collected larvae. Mines that seem likely to represent the same species have been found on an even wider array of plants in British Columbia and Alaska. Incidentally, I’ve noticed the opposite situation with Liriomyza schmidti, one of the most polyphagous of all agromyzid flies. Until recently, it was only known to occur in the Neotropics north to southern Florida, but Tracy Feldman has reared it in North Carolina and iNaturalist observers have found mines north to the DC area and west to Texas. Although it occurs on dozens of different plant families in Florida and South America, it has been found on just a few plant species farther north, mainly greenbriers (Smilacaceae: Smilax) and passionflowers (Passifloraceae: Passiflora).

John’s purple-striped jewelweed-mining larvae, which he also found in mines of M. erythranthei in water speedwell, are M. eurynotus. (It is unclear at this point whether the adults Armin initially identified as M. eurynotus were this species or M. erythranthei, because the two are very similar.) Whereas M. erythranthei larvae are leafminers throughout their development and pupate in their mines, older larvae of M. eurynotus feed on leaves externally, and it is not entirely clear whether they are able to establish mines in pristine leaves or whether there was some kind of initial damage that allowed them to enter the jewelweed cotyledons. Mike also collected M. eurynotus larvae together with M. erythranthei on Arctic sweet coltsfoot in Oregon.

To further complicate things, Mike also collected larvae from Arctic sweet coltsfoot, Siberian spring beauty, and forget-me-not that had purple banding just on the first two body segments; these belong to a Metriocnemus species that is as yet unnamed because no adults have been reared. Because Mike was not able to make detailed observations of these collections, it was not clear to what extent these larvae were mining the leaves versus feeding on the surface, but just the other day I came across this seven-year-old observation of what appears to be the same species on twistedstalk (Liliaceae: Streptopus) in Alaska. That larva was initially found feeding in a leaf mine, but some time after it was collected it was photographed feeding on the surface as with later instars of M. eurynotus.

And what about those Limnophyes species that figured prominently in John’s initial discovery of the water speedwell mines? Well, Mike reared over 20 adults of a new species in this genus from his collection of monkeyflower mines, and the larval exuviae seem to match the larva from John’s first video. Of the two females John had reared, this one appears to be the same species. Last year John also reared one male of this species from his collection of jewelweed cotyledons, and a few days earlier he had observed what may have been a larva of this species feeding in one of the mines along with a larger larva of M. eurynotus. Mike suggested the name Limonophyes viribus, a reference to a phoenix sculpture named Viribus (Latin for “strength”) that was erected in the town of Blue River after the devastating fire.

All this, and much more, is documented in our paper that was published yesterday:

Eiseman, Charles S., Armin Namayandeh, John van der Linden, and Michael W. Palmer. 2023. Metriocnemus erythranthei sp. nov. and Limnophyes viribus sp. nov. (Diptera: Chironomidae: Orthocladiinae): leafminers of monkeyflowers, speedwells, and other herbaceous plants, with new observations on the ecology and habitats of other leaf-mining Chironomidae. Zootaxa 5249(1): 41–68.

I optimistically included “Part 1” in the title of this post, because I hope someday there will be a “Part 2” in which we give a name to that other new species of Metriocnemus and work out its life history, confirm the identity of the midges mining all those other plants in Alaska, have more to say about that other Limnophyes species John reared (including what its larva looks like), and ideally document the whole life cycles of all these species. At this point we don’t know where any of them lay their eggs, and for the Limnophyes species it is unclear where they pupate, whether they are obligate associates of Metriocnemus, and if not, what they do when they aren’t feeding in Metriocnemus mines.

Celebrating Silky Willow

Simply not mowing the lawn, and welcoming whatever plants decide to grow in its place, has done wonders for the biodiversity of our yard. But we have also welcomed gifts of native plants from friends, and today I’d like to shine a light on a silky willow (Salicaceae: Salix sericea) shrub that Adam Kohl gave us a couple of years ago. We planted it in a moist spot at the edge of the woods, and last year it was discovered by several insects I hadn’t seen in the yard before. The first I noticed was this sawfly larva, which appeared on May 27:

Although I’ve made some good progress on my guide to sawfly larvae this winter, I haven’t yet tried to make a key to the willow-feeding species—and I think there are more sawflies on willows than on any other plant genus—so for now all I can say is that this is something in the subfamily Nematinae (Tenthredinidae). I of course collected it to see if I could rear it to an adult, and the next day it turned purple, indicating that it had entered the non-feeding prepupal stage.

I put it in a jar of soil, since most sawfly larvae burrow into the ground to pupate, but after wandering around for two days it spun a cocoon between two leaves.

So far, no adult has emerged; maybe one will when I take all my overwintering bugs out of the fridge in a few days.

When I visited the silky willow on June 2, I noticed evidence of a leafminer I hadn’t seen in my yard before:

A larva of Caloptilia stigmatella (Gracillariidae) had made a little underside tentiform mine in one leaf, then moved to a fresh leaf and used silk to roll the tip into a cone, where it was now feeding on the leaf externally, but within the shelter of the cone (as is typical of Caloptilia species). Both the mine and the cone were more conspicuous from below:

Caloptilia stigmatella has been reared from a variety of willows and poplars, but I have seen no records of it from silky willow, so I collected the leaf with the cone to make absolutely sure it was that species. Six days later the larva finished feeding and spun a cocoon:

Alas, before I discovered the Caloptilia larva, an ichneumon wasp had already laid an egg on (or in) it, and a week and a half after the cocoon was spun, her daughter emerged from it:

Meanwhile, on June 12 I noticed some more underside tentiform mines on the silky willow, but these were larger and more “tented,” indicating they were made by some species of Phyllonorycter (also Gracillariidae) instead of Caloptilia. Phyllonorycter species complete development in their mines instead of exiting to feed in leaf rolls.

If you tried to identify these mines using my key to willow leafminers, you’d get to Phyllonorycter and would then find that you need a reared adult to get further, because the leaf mines of the willow-feeding Phyllonorycter species all look pretty much the same. So I collected this leaf, and adults emerged from both of the mines five days later, leaving their pupal skins poking out.

Now, if the antenna weren’t obscuring the white streak along the costal margin at the base of the wing, the key I made would correctly identify this as Phyllonorycter scudderella (which also has not been reported from silky willow before). However, the first step in Davis & Deschka’s (2001) key to Salicaceae-feeding Phyllonorycter species ignores all external features and asks whether or not the male genitalia have symmetrical valvae. Here’s the answer:

The left valva is big and broad and the right one is little and shrimpy, just as in Davis & Deschka’s illustration for P. scudderella, and from there their key easily takes my moth to that species based on wing pattern. (For whatever reason, I am unable to get photos in sharp focus using my compound microscope’s lowest magnification, so I took three photos at higher magnification and quickly spliced them together here.) A year ago I posted photos of the genitalia of P. nipigon, which has symmetrial, slender valvae; see that post and the previous one for some explanation of what dissecting these tiny moths involves.

Anyway, on June 12 I noticed an adult sawfly on the silky willow, and I thought it might be the same species as the larva I’d collected two weeks earlier…

…but it turned out to be Thrinax dubitata (Tenthredinidae: Selandriinae), whose larvae eat sensitive fern (Onocleaceae: Onoclea sensibilis). Which makes sense, because there is lots of sensitive fern all around that willow. But this adult sawfly was more than casually interested in the willow, and for quite a while after that, every time I walked by, I noticed that numerous very tiny wasps (~1 mm long) were also very interested in it, scurrying all over its leaves. On July 7 I finally got around to bringing my camera over and investigating what they were up to—as well as confirming my suspicion that they were playgastrids. They scattered each time I got the lens near them, but I managed to get five of them in the frame in one shot:

All platygastrids (as the family is currently circumscribed) are parasitoids of gall midges (Cecidomyiidae), and there were no midge galls in sight. So what were these little wasps up to? It only took a few moments of watching them to realize that they were drinking from extrafloral nectaries along the leaf margin. In the photo below, note that each of the leaf serrations has a round appendage on the left side, and each of these appendages has a little droplet of delicious honeydew bubbling out of it.

Here’s a closer view of three of these nectaries from the underside of the leaf, with the droplets coming out on the right side:

I had previously only noticed extrafloral nectaries on the petioles of leaves (like cherry), so this was all news to me.

Getting an in-focus photo of one of these wasps, as it briefly sipped from one nectary before moving on, was pretty challenging, but I at least managed to document them doing it.

As I explained in my previous post about extrafloral nectaries, the idea is that they attract predators such as ants, whose presence will result in fewer herbivorous insects munching on the leaves. I suppose it’s possible that these platygastrids could be helping the plant by defending it against gall midges, but galls don’t really impact the health of the plant and I think these wasps are pretty much freeloaders. There was, however, a big ol’ ant that came along to partake of the nectaries while I was trying to get pictures of the platygastrids.

And, in retrospect, that’s what the adult sawfly had been up to as well.

Obviously attracting sawflies isn’t necessarily what the plant is going for, since larvae of many species eat willow leaves, but adults of some species are predatory—in fact, here is one chomping on a platygastrid—and the yellow dusting on this one’s head and thorax indicate that it has also been visiting flowers for nectar, so it is a potential pollinator as well. As is so often the case, whether an insect is “beneficial” or “detrimental” is not so clear-cut here, and it makes no difference to me. The bugs that come to eat the plants, and the bugs that come to eat those bugs, are all equally welcome in my yard.

Behind Door #1…

When Julia was in high school, she built this little cabin in the woods behind her family’s house in central Ohio:

One chilly morning last April, when we stopped there on our way to spending a week exploring the Ozarks, we took the door off the hinges so that its rotten bottom could be repaired (the result can be seen in the above photo). We carried it back to her parents’ driveway and laid it on the ground, with the inside facing up, and I was surprised to see a greater bee fly (Bombyliidae: Bombylius major) clinging to it.

I’ve rarely even attempted to photograph these flies because they are normally in constant motion as they buzz from one spring wildflower to the next like tiny hummingbirds. I guess they have to sleep sometime though, and this one hadn’t yet thawed out from the previous night’s freezing temperatures, so I was able to get a close look.

As the above photo makes clear, it was resting on the webbing associated with a cottony-textured spider egg sac. Fluffy ones like this are usually the work of either orbweavers (Araneidae) or cobweb spiders (Theridiidae). Right next to it was a smooth, disc-shaped egg sac like this one:

Egg sacs of this form are generally the work of hunting spiders (e.g. crab spiders) as opposed to those that spin webs to catch their prey. These particular eggs sacs had distinctive radiating “spokes” of silk around their margins. That may be indicative of a particular species, but I have no idea which one!

Also note that in the crack right next to the above egg sac, there is a web of a tube web spider (Segestriidae: Ariadna bicolor). These spiders wait in their tubes and dart out to grab passing insects that bump into the fine strands of silk that radiate from their entrances. Here are two more tube webs:

While I was taking pictures of all these things, some tiny, previously unnoticed bugs started to warm up enough to wander around on the door. One was this ~3.5 mm long moth:

This is Phyllonorycter celtifoliella (Gracillariidae), which as a larva forms underside tentiform mines in hackberry leaves. Most Phyllonorycter species seem to overwinter as pupae in their mines, but the one time I reared this species, the adult emerged in October. This one found under loose bark in Iowa in January confirms that this species overwinters as an adult. …Okay, it’s dead, but I’m pretty sure the photographer killed it to take the photo. Here is a live one that was among a group of 60 or so found in Nebraska in November, which “were tucked behind the bark of a dead oak tree and were hiding amongst the silk cocoon, larval and pupal exuviae, left over from a Giant Leopard Moth.” So I may have been witnessing this moth waking up in the spring for the first time, after having spent the winter behind the door of Julia’s cabin. (This was not the case for the bee fly, which overwintered as a pupa in the burrow of a ground-nesting bee.)

And wandering about among all of these things were numerous garden springtails (Bourletiellidae: Bourletiella hortensis), at most 1 mm long, which came in a variety of colors:

Beyond what lives behind the door to Julia’s old cabin, the woods immediately surrounding it are the type locality for Phytomyza aesculi and P. hydrophyllivora (Agromyzidae), and are also where I found this lovely moth that bores in Ohio buckeye petioles, and where I photographed a bunch of different bugs visiting narrow-leaved spring beauty flowers a few years ago.

Wingless Weirdos

Ever since I made a place on BugGuide to collect photos of them over a decade ago, I’ve been wanting to see (in person) one of those weird wingless gall wasps that can be found throughout the winter. Two years ago I put them on the “winter bug bingo” card I made for the online “Bugs in Winter” course I put together, and I think one participant managed to find one, but I wasn’t so lucky.

Last fall at the end of a game of tennis, I noticed a white oak leaf at the edge of the court with a couple of “oak pea galls” on it, like this one:

This gall is caused by Acraspis pezomachoides (Cynipidae), and knowing that Acraspis is one of the genera with wingless adults, I decided it was time to be a little more proactive in my quest to see one, so I took the leaf home and stuck it in a jar. But alas, I just got a couple of lousy parasitoids.

Last month, while leading a workshop on identifying invertebrate tracks and sign, I picked up a white oak leaf with an “oak hedgehog gall” on it—made by the related species Acraspis erinacei. It was already brown like the one pictured above, but here’s what a fresh one looks like:

I decided to try again, so after everyone had gotten a good look at the gall, I had Julia put it in her backpack.

A week or so ago, I remembered the gall and had Julia fish it out of her backpack. I put it in a vial on a shelf in my office, and every couple of days I’ve remembered to check the vial (most of my other bugs having been put away for the winter at this point).

Last night I checked, and there she was!

Here’s what the gall looked like after she emerged (the exit hole is at the bottom, near where it’s attached to the leaf).

The adults that emerge from round, faceted galls like this—provided that they are not parasitoids or inquilines—are all wingless females. Like most cynipids, Acraspis species have a two-part life cycle. These females climb up to white oak leaf and flower buds and lay eggs in them. Tiny, inconspicuous galls form in the buds (see examples at gallformers.org), and winged males and females emerge from these in the spring. After mating, females lay eggs in midribs of white oak leaves, and the galls that will produce the next set of wingless females develop over the summer.

Virtually all of the bugs I raise are unknowns that have to be killed and preserved to be identified, so it was nice, for a change, to raise one that already has a name and whose whole life cycle has already been worked out. This morning I took her out to a white oak sapling in the woods behind my house and set her on it, thinking maybe I’d get to see her lay some eggs.

No such luck; she didn’t seem to like this sapling, and started making her way down its stem. So I moved her to the trunk of the white oak tree that was right next to it. There, she decided to just sit and preen for a long, long time.

It was below freezing out and my fingers were getting cold, so I decided to leave her to it.

When I stopped to feed the chickens on my way in, I found another wingless weirdo waiting for me by the door of the shed: a female fall cankerworm moth (Geometridae: Alsophila pometaria). ‘Tis the season, I guess! Her eggs will overwinter, hatching in the spring into inchworms that will nibble the leaves of the apple or cherry tree overhead, from whence she presumably came.

More wingless wonders await—I’m always excited to find a snow scorpionfly or snow fly trudging across the snow in winter.

Oh, and tonight I checked the vial with the gall again and discovered that another Acraspis erinacei female has emerged. As noted on gallformers.org (which I highly recommend for identifying galls and reading up on what’s known about them), these galls may contain between two and eight central cells with individuals of A. erinacei (or their parasitoids) developing in them, as well as additional cells around the periphery with inquilines developing in them. Inquilines are (in this case) cynipid wasps that develop inside the galls induced by other cynipid wasps, without (necessarily) killing the original inhabitants. Twelve winters ago, before I knew anything about the life cycle of Acraspis species, I collected some A. pezomachoides galls from under a white oak tree, assuming that what emerged would be Acraspis adults, but instead I got nothing but inquilines, which emerged in early June—thereby skipping the alternate, bud gall-inducing generation of their host species, and appearing just in time to find some developing “pea” galls to lay eggs in. This one’s a male:

Can gall midges be leafminers?

The Leafminers of North America project I created on iNaturalist a few years ago has been an excellent way for me to collect new host plant and geographic distribution records for known leafminer species, as well as to identify new mysteries in need of investigation (there are now nearly 1000 rows in my spreadsheet of mystery leaf mines). However, although the vast majority of observations added to the project actually show leaf mines, there are regularly also photos showing things like fungal or viral diseases, or even pine pitch that has landed on the surface of a leaf. Many photos do in fact show evidence of insect feeding, but with “window feeding“—where one leaf epidermis is consumed and the other is left intact—mistaken for leafmining, where by definition both epidermises are left intact and the insect larva feeds between them. Some people simply are not aware of what defines a leaf mine, and post photos of insect feeding where both epidermises are consumed. It was because of this mistake, incidentally, that I happened to see this observation of feeding sign on an elm leaf in Quebec, which I suggested was the first evidence of the Asian “elm zigzag sawfly” (Argidae: Aproceros leucopoda) in North America, which led to this paper confirming its presence here; this discovery was cited in another paper, published a few days ago, as an example of “The benefits of contributing to the citizen science platform iNaturalist as an identifier.”

A distinction that is a lot less clear is where the line is between leaf mines and galls, since many gall-inducing insects do live and feed between the epidermal layers of leaves. In particular, the galls caused by some midges (Cecidomyiidae) are so flat that they don’t seem to have deformed the leaf at all. One gall midge, Monarthropalpus flavus, has even been given the common name “boxwood leafminer,” even though it does cause distinct swellings on leaves, which shouldn’t be mistaken for mines.

Back in July 2013, when I was in the early stages of putting together my leafminer book, I asked gall midge specialist Ray Gagné whether any cecidomyiids could be considered leafminers:

In considering what to include in this book on leafminers I’m working on, I’m wondering if any gall midges qualify. I note that Monarthropalpus flavus is given the name “boxwood leafminer,” but I’m unfamiliar with its gall and don’t know whether it deserves the title any more than any number of other midges that make flattish leaf galls. When I’ve seen occupied spot galls such as those on Smilax, Uvularia, or the Cornus ones I sent you today, they seem very similar to the “blotch” mines produced by sap-feeding gracillariid moth larvae. I suppose what I’m asking, essentially, is whether the size and shape of such galls is determined by the movements of the larva, as in a leaf mine, or whether they are formed in some other way. I haven’t been able to watch them for any considerable length of time, but seeing the larvae positioned non-centrally in these galls suggests to me that they do, in fact, move around, enlarging the spot as they feed.

Ray’s response:

As to whether they mine the leaf, I have never myself observed their behavior closely or that of the other leaf spot gallmakers. I have read that the boxwood pest, an extremely active larva, feeds in a circular fashion, the reason the gall features an empty circular space. One has to take into account that cecidomyiid larvae have piercing-sucking mouthparts, unlike agromyzids and other miners, so I suppose the cecidomyiids both suck the juice from surrounding cells and possibly cause more cells farther along the periphery to produce additional food. That is analagous to what is going on in the Macrodiplosis leaf swelling on oaks, except there you wouldn’t call the cecidomyiid larvae leaf miners. For that reason, I wouldn’t list the Parallelodiplosis or the Mon. flavus as leaf miners, although I certainly can understand why you might do so for completeness in a leafminer book.

The Cornus (dogwood) leaf spots I mentioned and the Parallelodiplosis Ray mentioned were both referring to Parallelodiplosis subtruncata, which I wrote about in January 2014. In that post I was focusing on the “green island” phenomenon I’d seen in connection with galls of this species I found in Idaho in September 2012, and I made no mention of the observations I’d made of the same species in my own yard just a few months before I wrote the post.

On September 26, 2013, I noticed these two galls on a leaf of alternate dogwood (Cornus alternifolia) at the edge of my yard.

Flipping the leaf over, I saw that each gall still had a larva inside.

So I decided to monitor their progress to see if the galls got any bigger. Here they are on September 27:

September 28:

September 30 (with some condensation inside after it rained the previous day):

October 2:

October 3:

October 7, after the larvae dropped to the ground.

If you compare each photo to the previous one, you’ll see that the size and shape of the little blisters containing the larvae doesn’t change at all. Each larva is just squirming around within the cavity that the plant has created in response to its presence, drinking the juices. So although these galls are superficially similar to leaf mines, the larvae are not doing any actual mining.

I should mention here that some gall inducers do have chewing mouthparts and actively excavate the tissue within the galls. Those that come to mind that feed in leaf galls include the moth Heliozela aesella (Heliozelidae) on grape, and “Pontania” sawflies (Tenthredinidae, now placed in the huge genus Euura) on willow. But their galls are obvious swellings/deformities in the leaf tissue, and no one would confuse them with mines.

I should also mention, maybe, that not all leaf mines are flat. “Underside tentiform mines” are sometimes mistaken for galls because of the way they distort the leaf. However, they start out as normal, flat mines excavated by the larvae, and the distortion is the result of the older larva spinning silk within the mine; there is no manipulation of the growth of the plant as there would be in a gall. The silk contracts as it dries, causing the edges of the mine to draw together, which results in a wrinkled lower epidermis and the upper epidermis buckling to form a roomy “tent.” This is a useful adaptation for avoiding parasitoids and predators, since the larva now has three dimensions in which to try to escape, instead of just two.

Incidentally, here’s what the Parallelodiplosis galls looked like on the upper surface on October 7, when I found them empty:

By October 11, there was a bit of a “green island” effect, but obviously not of any consequence to the well-being of these particular larvae.

Another writing season begins!

Things have been quiet around here on BugTracks lately, due to another busy field season (and due to spending a good chunk of my summer computer time updating the 300+ page Asterales chapter in Leafminers of North America, which is now finished). Any day now I’ll start going through my photos from this spring and summer and will be posting the highlights here, as soon as I finish up a few papers I’ve been working on about—you guessed it—leafminers and sawfly larvae.

In the meantime, a box of 2023 Leafminers of North America calendars has just arrived, 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). As with last year’s calendar, each month shows a whole leafminer life cycle instead of a single full-page photo per month.

Also, last month when the “January” issue of Proceedings of the Entomological Society of Washington was finally published, it included four papers of mine, three of which reported on discoveries made during my 2020 inventory of leafminers and sawfly larvae in my yard (and the fourth included something I found in my neighbor’s beaver meadow). Here’s a quick summary of those discoveries, with links back to my original blog posts about them.

Eiseman, Charles S. and Owen Lonsdale. 2022. First North American record of Phytomyza origani Hering (Diptera: Agromyzidae), a leafminer of cultivated herbs in the mint family (Lamiaceae). Proceedings of the Entomological Society of Washington 124(1): 177–183.

As I had assumed, this leaf mine I found on the oregano by my front door on June 20 proved to be the first North American record of Phytomyza origani. Since this species was thought to be a strict specialist on oregano, it was a little surprising when the leaf mines on apple mint (which I first noticed in Julia’s water glass) turned out to be the work of the same fly. Coincidentally, within a month of my rearing P. origani from apple mint in my yard, Yuliia Guglya reared it from other Mentha mints in Ukraine, as I learned about when I was given her paper to review last spring (which happened to be the same week that Owen Lonsdale examined and identified my flies).

Eiseman, Charles S., David R. Smith, Bill Sheehan, and Tracy S. Feldman. 2022. Macrophya Dahlbom spp. (Hymenoptera: Tenthredinidae) feeding on Asteraceae. Proceedings of the Entomological Society of Washington 124(1): 39–45.

This little cutie that I found on the underside of a Canada goldenrod leaf by the driveway on June 13,

as well as this snazzy older larva I found on late goldenrod by the chicken run on June 21,

both turned out to be Macrophya senacca, a species that Gary Gibson had described when he revised the genus Macrophya in 1980, but nothing had been known about its immature stages or host plants until now. Both larvae burrowed into jars of soil and emerged as adults the following spring.

Eiseman, Charles S. and David R. Smith. 2022. A review of the Nearctic fern-feeding sawflies (Hymenoptera: Tenthredinidoidea), with new host records and larval descriptions. Proceedings of the Entomological Society of Washington 124(1): 18–38.

On June 6, while gazing down at a garden from the back deck, I spotted this larva on a clump of lady fern,

and once I’d brought it inside I discovered this tiny larva on the same frond,

and four days later this wee one appeared in the same rearing jar, apparently having hatched from an unseen egg. I found more of these larvae, and the eggs from which they were hatching, when I collected fresh lady fern fronds to feed the original larvae.

It was a bit tricky to keep track of who was who, when more eggs and larvae kept coming in every time I collected more bits of lady fern, but I was able to rear all three species to adults. The first larva emerged as an adult the following spring, and turned out to be—as I’d guessed it might be—Strongylogaster macula, which had previously been reported only from Europe and Canada.

The second larva bored into a sumac twig I offered it and emerged as an adult the following spring, revealing itself to be Thrinax albidopicta, whose larva hadn’t been described before (and previous host records attributed to this species were based on misidentifications). Other larvae of that species that I collected after the first one emerged as adults without any diapause, the first one on June 22. As they get older, larvae of T. albidopicta develop adorable little black hats.

And the third larva turned out to be Aneugmenus flavipes, a species previously known to feed only on bracken fern; the first adult I reared from lady fern emerged on June 29.

Eiseman, Charles S. 2022. New rearing records reveal Phytosciara greylockensis Eiseman, Heller, and Rulik (Diptera: Sciaridae) is a polyphagous leafminer of herbaceous plants. Proceedings of the Entomological Society of Washington 124(1): 174–176.

The title of this one pretty much says it all; when Julia and I first discovered Phytosciara greylockensis at the 2016 Berkshire BioBlitz on Mt. Greylock, the larvae were feeding on bluebead lily, but when we were conducting a survey for rare dragonflies along the shore of a small river in 2020, I found them on buttercup, violet, water pennywort, and sensitive fern all within an area of about a square meter, and then a couple of weeks later I found one on a monkeyflower leaf in my neighbor’s beaver meadow.

And for completeness, here are two more papers that were published within a day after the above four came out. These two aren’t about my yard and I wasn’t the lead author, but unlike the first four they are open access so you can follow the links below to read them online if you want (if you’d like a PDF of any of the others, let me know).

Xuan, Jing-Li, Sonja J. Scheffer, Owen Lonsdale, Brian K. Cassel, Matthew L. Lewis, Charles S. Eiseman, Wan-Xue Liu, and Brian M. Wiegmann. 2022. A genome-wide phylogeny and the diversification of genus Liriomyza (Diptera: Agromyzidae) inferred from anchored phylogenomics. Systematic Entomology 2022: 1–20. (full article)

Chen, Taibin, Xiaohua Dai, and Charles Eiseman. 2022. A checklist of gymnosperm-feeding leafminers (Arthopoda, Insecta) in North America and Europe. Biodiversity Data Journal 10: e91313. (full article)

Okay, signing off for now!

Dogwood Mysteries

As I go through my Leafminers of North America e-book and update each chapter for the (now nearly complete) second edition, I’ve been putting together a spreadsheet of mystery leaf mines that need further investigation. There are now over 700 rows in that spreadsheet, and new mysteries continue to be added faster than old ones are solved.

Today Julia and I drove 4.5 hours (round trip) to explore a site in western Vermont with the hope of investigating one of these mysteries—a nepticulid moth that so far is known only from a few empty mines scattered across eastern North America. I first became aware of this species several years ago when Erik van Nieukerken told me that, while perusing the pressed leaf mines that are preserved in the Canadian National Collection, he had seen mines of an unknown nepticulid on dogwood leaves from Ontario. Later, while working either on the dogwood key in my book or on my first paper on agromyzid flies with Owen Lonsdale, I discovered that I had photographed one of these mines in western Iowa in September 2012 and had filed it under Phytomyza agromyzina. P. agromyzina is a leafminer of dogwoods that is common across North America as well as in Europe and Asia; here is a typical example on a leaf of alternate dogwood (Cornus alternifolia):

Here is the mystery moth mine from Iowa, found on roughleaf dogwood (C. drummondii):

Both are simple linear mines, but whereas the frass trail of the agromyzid fly alternates from side to side (this is most evident toward the end of the mine), the nepticulid moth deposits its frass in a central line. This is because the fly larva lies on its side while it feeds, periodically rolling over onto the other side, while the moth larva lies on its back or on its belly.

The central frass line is more clearly visible in this fresh (but apparently aborted) mine I photographed on flowering dogwood (C. florida) in southeastern Ohio in early August of 2016:

The third time I found one of these mines was a few months later, in October 2016, at the site in western Vermont we visited today:

This example was on gray/panicled dogwood (C. racemosa). Although the frass pretty well fills the width of the mine and it’s not easy to see that it forms a central line, on close inspection it is made up of closely spaced zigzagging arcs, which are characteristic of Nepticulidae.

And I have never seen another of these mines since, including today. (The trip was still worthwhile, since we got to explore a beautiful place as well as add two species to the list of moths known from Vermont and collect a couple of mines of another mystery moth.) Nor has anyone else, as far as I know. Just to be sure of this, this evening I reviewed the ~100 iNaturalist observations of Phytomyza agromyzina that I hadn’t already looked at. As a result of this exercise (which involved weeding out a number of observations that didn’t show P. agromyina, or even leaf mines or dogwood in some cases), there are now 550 verified observations of P. agromyzina on iNaturalist, and I have one more mystery leaf mine on dogwood to wonder about, thanks to this leaf that Jeff Clark photographed in Virginia last October:

Gracillariid leaf mine on dogwood (Cornus sp.) © Jeff Clark; Creative Commons license

This mine has a central frass line as in the nepticulid, but the silvery-whitish color indicates that it was formed entirely in the leaf’s epidermal cells, as opposed to in the mesophyll. Also, the frass is in a continuous line rather than composed of tiny particles, indicating that the larva was consuming only the liquid contents of the cells. This type of mine is characteristic of moths in the family Gracillariidae, and this is the first I’ve heard of a gracillariid making a long, linear mine in dogwood leaves (there is an unknown Marmara species that makes linear mines in dogwood stems, but that’s another story). This looks very much like a Phyllocnistis mine, but without seeing that it ends in a silken pupal chamber, I can’t be sure that that’s what it is*. Here’s a link to Jeff’s original observation, which includes the full-resolution photo as well as a second photo showing another leaf with the same type of mine.

So if there are any dogwoods near you, I’d greatly appreciate it if you could keep an eye out for either of these mystery mines, and please collect any you find! Even mines with dead larvae inside would be tremendously valuable, since it may be possible to match them to adult specimens through DNA barcoding. And if you find any occupied agromyzid mines, those would be worth collecting for rearing too: I recently reared some adults from these mines that Owen Lonsdale identified as Phytomyza notopleuralis, which probably should be synonymized with P. agromyzina, but more specimens are needed to demonstrate that there is no clear line between the two species. For further details about that, see:

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.

Phytomyza agromyzina reared from alternate dogwood (Cornus alternifolia)

Phytomyza notopleuralis reared from red osier dogwood (Cornus sericea)

* Edit, 8/21/2022: Natalia Kirichenko just reminded me about this paper, published four years ago, which discusses four species of dogwood-mining Phyllocnistis species in Northeast Asia, describing three of them as new. Could the Virginia species be one of them? All four have publicly available DNA barcodes, so that question would be easy to answer if someone can collect a mine with a larva or pupa inside…

A Curious Flower

Today I break my four-month silence to bring you this:

Yesterday morning while we were eating breakfast on the back deck, Julia exclaimed something like “The poop beetles are eating the groundcherry!” This wasn’t news to me; a week or so ago I had noticed the tiny larvae, with poop piled on their backs, on a leaf of one of the potted groundcherry plants we had overwintered indoors with the hope of actually getting some fruit out of them this year. But when I looked over at the plant now, I saw the reason for her alarm: the top of the plant had been reduced to a “Y” of two blunt, naked branches, and when I went over to inspect, I saw that each fork of the Y was topped with a “flower” of larvae that were working together to munch the branch down to nothing. I thought their symmetrical arrangement produced an image that, while somewhat stomach-churning—especially in the middle of breakfast—was also oddly compelling. So of course I ran to get my camera. And then I gathered up all the larvae and threw them to the chickens, even though I knew they would react exactly as they did: come running up excitedly to see the latest offering, then stop suddenly a foot or two away, cock their heads quizzically, and walk away.

If you’re not familiar with these larvae, here’s a side view of the same scene to give you a better sense of what we’re looking at:

They are larvae of the three-lined potato beetle (Chrysomelidae: Lema daturaphila, or another similar Lema species). And being the good botanists that they are, they know that groundcherries (Solanaceae: Physalis) have nothing to do with cherries (Rosaceae: Prunus), but belong to the nightshade family, along with potato, tomato, eggplant, and goji.

Here’s an adult found on our deck railing last June—when I don’t think we had any nightshades there to speak of:

And another on one of our goji bushes seven years ago, being inspected by a group of Lasius ants.

Carrot Stem Dwellers

Carrot (Apiaceae: Daucus carota) is native to Europe but widely cultivated and has become a ubiquitous weed in North America (also known as Queen Anne’s lace), so you’d think we’d have a pretty good handle on what bugs eat it by now. You’d be wrong.

Black swallowtail caterpillars (Papilionidae: Papilio polyxenes) are well known to feed on a variety of native and nonnative plants in the parsley family, and I often see them munching away on wild carrot leaves in my yard…

…but I’ve also come across a surprising number of other carrot-feeding insects in my yard that don’t seem to have been documented before. In 2017 I reared two adults of the micro-moth Epermenia albapunctella (Epermeniidae) from larvae that initially made tiny mines in the leaves, later feeding externally from little webs. This species was not previously known to feed on carrot, or to mine leaves. When I did my intensive year-long cataloguing of leaf and stem miners in my yard in 2020, it was #40:

And then #179 was a stem-mining fly; the relevant section of that post is repeated here:

[Begin quote]

Leaf (stem) miner #179: Ophiomyia sp. (Agromyzidae), on wild carrot / Queen Anne’s lace (Apiaceae: Daucus carota). I was excited to find this mine on the evening of September 5:

No Ophiomyia is known to feed on wild carrot, but Julia and I found a bunch of similar mines on an isolated clump at Black Rock Forest in New York late last August while conducting our survey for leaf-mining moths there. The puparia in those mines were all black, and only eulophid wasps emerged from them. The puparium in the above mine (visible as a bulge along the upper margin of the stem) was whitish; unfortunately it turned out to be empty already.

In this close-up, the pair of little black anterior spiracles of the puparium are visible poking through the stem epidermis at far left, and there is a longitudinal opening associated with those—along with a more conspicuous transverse slit to the right of them—indicating that the fly has already emerged. I spent a good chunk of yesterday pulling up wild carrot stems around the yard, and I found six stems with intact puparia (plus one more empty one, and one or two that seemed to still have larvae in them). To give a sense of how sparsely distributed these mines are, this is how many stems I had to inspect to find a half dozen of them (note Brenda in the background; she followed me around for most of the time that I was pulling them up, and was often literally underfoot):

All of the mines were confined between two nodes in the stem as in the example shown above. John van der Linden has observed similarly constrained stem mines (both agromyzid and Marmara) on Ageratina altissima, Polymnia canadensis, and Veronicastrum virginicum in Iowa.

[End quote]

That’s where I left the story, so I’ll pick it up from there. At the beginning of October 2020, this braconid wasp (subfamily Opiinae) emerged from one of the six puparia I’d collected on September 6.

When I looked at the puparia under magnification to figure out which one it had come from, I discovered that two of them had exit holes (one of them had evidently only looked intact to the naked eye), so now I just had four left. I assume this braconid came from the puparium with the more conspicuous hole:

On October 16 I put all of my rearing projects into the fridge for the winter; I took them back out on March 1 of last year. On March 29, another parasitoid emerged: this time, a pteromalid in the genus Herbertia.

Nothing ever emerged from the remaining three puparia. So naturally I was watching closely for the first mines to appear last summer, and I spotted the first one on August 4. This prompted me to spend the next couple of hours pulling up every wild carrot stem in the section of my front yard bounded by the driveway, upper vegetable garden, and shed, yielding a total of four mines: three in stems, each of which already contained a greenish-white puparium like the one toward the right side of this photo…

…and one mine in a leaf stalk, in which a larva was still feeding (at right):

I suspect that in this species a black puparium is an indication that a parasitoid will emerge, and a whitish puparium means there is some hope of a fly emerging.

When I went to pull up the last stem before quitting for the day, I was shocked to discover that not only did it have two mines in it, but they were Marmara (Gracillariidae) instead of Ophiomyia.

There are no previous records of Marmara from wild carrot, or from anything else in the parsley family for that matter. But the continuous central frass line in these mines told me at once they were Marmara; in Ophiomyia stem mines the frass is much less conspicuous, and it is deposited either in widely spaced grains or in little strips that alternate from side to side. One of the Marmara larvae is visible to the right in the above photo, but it’s a little hard to make out. Here’s a close-up of the other larva, with its head pointing toward the upper left corner:

Needless to say, I stuck this stem in a ziplock bag to see if I could rear the larvae to adult moths.

On August 6, I pulled up all the wild carrot stems from another section of the yard, found a few more puparia, and three days later an adult Ophiomyia emerged from one of them! For some reason it was already dead when I found it, even though I’d been checking the rearing vial regularly.

It’s a female, which means that when Owen Lonsdale gets around to examining it, all he’ll be able to tell me is that it’s some kind of Ophiomyia. Without male genitalia, I’m no closer to getting a name on this fly than I was when I just had parasitoid wasps.

On August 14, another fly emerged! …Another already-dead female.

On August 13, a braconid emerged—this time belonging to the subfamily Alysiinae.

Alysiine braconids have weird, outward-facing mandibles that they use to pry open the host fly’s puparium along an existing line of weakness at the anterior end, so that the emerging wasp leaves an opening similar to the one an emerging fly would leave, as opposed to the ragged-edged hole an opiine braconid chews.

On August 12 I stripped yet another section of my yard of its wild carrot stems, found a few more puparia, and two days later a fly emerged from one of them! …Another sorry-looking female.

Another alysiine braconid from the August 6 collection emerged that day. On the 15th, the fly that I had collected as a petiole-mining larva on August 4 emerged as an adult… another lousy female.

It’s still a mystery to me how one fly after another managed to make itself so dead in such a short amount of time. On August 17, another adult emerged—from another carrot-pulling session on August 10 that I guess I neglected to mention—and this one was alive!

…But it was just another female. How many females do I have to rear before we decide that this must be a parthenogenetic species, and there never will be any males? I don’t know, but more than five.

On August 21, a pteromalid emerged from one of the August 6 puparia; this time a miscogastrine rather than a herbertiine.

On August 22, another alysiine braconid.

On August 25, one of the Marmara adults emerged! It had rubbed some of its wing scales off in the bag, but that was okay; as with the flies, distinguishing them is all about the male genitalia.

Two days later, the other Marmara! It was a little drunk for some reason and kept flipping on its back, so its wings were even more rubbed than the first one’s, but no matter; they both had abdomens, and that’s what counts.

I pretty thoroughly inspected the carrot stem from which they had emerged and couldn’t find either moth’s cocoon. Some Marmara species exit their mines to spin cocoons, and others cut out a little flap in the stem epidermis at the end of the mine and spin their cocoon under that. I was too busy with fieldwork to keep looking right then, but I wanted to know what this species does, so I kept the stem in the bag to examine again when I had more time.

On September 1, another miscogastrine pteromalid emerged from one of the Ophiomyia puparia.

On September 9, this little dark-winged fungus gnat (Sciaridae) appeared in the bag with the Marmara-mined stem.

I had continued to pull up wild carrot stems from my yard throughout August. An Ophiomyia puparium I collected during the August 21 session produced this eulophid wasp (subfamily Entedoninae) on September 6:

On October 11, I looked over at that bag with the Marmara-mined stem in it, and there were several more of those dark-winged fungus gnats in it. There was also a weevil:

I had noticed some powdery frass coming out of a hole in that stem a while back, so I knew there was some kind of larva boring inside it, and it didn’t come as a complete surprise to see the weevil in the bag. With a quick internet search, I learned that there is a species that looks sort of like this called the carrot weevil (Curculionidae: Listronotus oregonensis); the sources I found mentioned it feeding on the root, but I figured the focus was on that because that’s the part people care about, and it seemed plausible that the same species could also bore in carrot stems.

I surmised that the fungus gnats must have been developing inside the weevil’s tunnel, feeding as larvae on its frass and the damaged/dying plant tissue. By November 5, a total of 60 of them had emerged. Sixty!

I sent the weevil to Bob Anderson at the Canadian Museum of Nature, along with some others I’d accumulated over the past few years, and he told me, “The mystery weevil from Daucus is a Listronotus but I don’t think it’s oregonesis as it’s a bit small for that species.” No comment on what he did think it was.

I sent the fungus gnats to Kai Heller in Germany, and he reported: “All individuals belong without doubt to the same species, namely Bradysia impatiens. This is the common greenhouse midge, which has a worldwide distribution. . . Unfortunately this is not a very interesting record.”

I sent the flies to Owen Lonsdale, who hasn’t had a chance to look at them yet, but we already know what he’ll say, since no males ever emerged.

Probably no one will ever look at the wasps.

As for the Marmara specimens, they came along at an inopportune time, when Julia and I were both impossibly busy, and they were part of a batch of moths that were left on spreading boards for several weeks in a box that had no mothballs left in it. Some time in the fall, we discovered that booklice had eaten most of the abdomens in the box, and the Marmaras were not spared. In fact, one of them is now nothing more than a thorax on a pin.

I’m reminded of this tragedy every day, because back in June, a booklouse appeared in my camera’s viewfinder:

It hung out in the upper left corner there for a few days, then it disappeared for a week or so, but then it reappeared, changing position a few times, until it finally died right near the middle of the field of view, where it still is to this day.

On the plus side, just a few more months until more wild carrot stems start popping up all over my yard; maybe it will all go better this time around!