Rhubarb Riddle

To make up for some of my recent extra-long posts, here’s one that’s short and sweet… If something involving rhubarb can be called sweet.

The vast majority of email queries I receive are along the lines of, “here’s something I wondered about and I figured it was easier to just ask you than look it up in your book.” But every once in a while, I get one in the form of, “I found this weird thing I’ve never seen before, and I couldn’t find anything like it in your book or in the whole internet!” The latter type is of course more interesting to me, but sometimes I can’t do much to help besides put the thing on the internet and see what happens. So here goes.

Yesterday David Gregg of the Rhode Island Natural History Survey found this thing growing out of the midrib of a rhubarb leaf at his house:

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I’m thinking that if there were a regularly occurring gall on a common garden plant like rhubarb, it would be well documented. So I suspect this is some kind of freak mutation. The thing at the end of the “string” coming out the middle of the “satellite dish” looks vaguely like the winged fruit of rhubarb, so maybe this one part of the plant just got some mixed genetic signals? Has anyone seen something like this before, or does anyone have anything more intelligent to say about it?

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The Yard List(s), Part 10

Yikes, I let more than a week go by since my last report on the yard lists. I guess I’m due for an update! First the leafminers…

#32: Pegomya bicolor section (Anthomyiidae). On May 30 I saw the beginnings of mines on several curly dock plants (Polygonaceae: Rumex crispus) around the yard; several closely related Pegomya species have been reared from this host, of which P. bicolor is the one I’ve confirmed in my yard (reared from sheep sorrel, R. acetosella), but I suspect this one is actually P. solennis (the one I’ve reared every time I’ve collected leaf mines on “dock” species elsewhere). Pegomya mines are easily recognized by the white eggshells on the lower surface; in this case there were seven, but only two larvae were still in the mine—whether they left in search of more elbowroom or were eaten, I’m not entirely sure, but a couple of holes are evident in the upper surface of the mine.

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There are at least two generations per year, so these larvae will become adults within a few weeks.

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#33: Agromyza alnibetulae (Agromyzidae). On May 31 I spotted two mines on a little paper birch sapling (Betulaceae: Betula papyrifera) that we’ve decided to let grow, for now, in the sloping semi-wild garden on the west side of our house. Agromyza alnibetulae is a European species that has not been confirmed to occur in North America, but I’m guessing it’s the same species mining birch leaves here (and probably native rather than a recent introduction). The mine below was already empty, and the other one was aborted.

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Luckily I succeeded in rearing this species last spring (from mines collected the previous spring), so we’ll learn the identity of this fly once Owen Lonsdale gets a chance to examine my specimens.

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#34: Agromyza princei (Agromyzidae). On June 3, on my way to check on the chickens after a long walk in the woods, I was excited to see these mines on a black raspberry (Rosaceae: Rubus occidentalis) that is growing under the black cherry tree by our shed (the same clump of raspberry with some stems drooping due to Pegomya rubivora feeding inside).

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I have only seen a single mine of Agromyza princei before, and the species is known only from the single adult that emerged from that mine a year after I collected it. The similar mines of A. vockerothi are common on all sorts of raspberries and blackberries, but I’m fairly sure these are A. princei because of the way they get a little blotchy toward the end, and have discrete, closely spaced frass grains almost from the very beginning; the one confirmed mine of A. princei was also found on black raspberry, and likewise on June 3. Agromyza vockerothi mines start showing up a little later in the season.

As of yesterday, all three larvae had exited their mines and formed puparia:

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Back in April I showed mines of Landryia impositella (Scythrididae) on heart-leaved aster (Asteraceae: Symphyotrichum cordifolium) and said the adults would appear in June. I saw the first one on June 3, resting on an aster leaf right next to the house:

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For several days I had been unable to locate the Marmara fraxinicola larva mining in the white ash branch in the vase on the kitchen counter; its path was no longer easy to trace as it doubled back on its previous mine. But on the morning of June 5, it had cut out the bark flap at the end of its mine, under which it was now spinning its cocoon:

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Its completed mine extends 22 cm toward the tip of the branch from the eggshell, then 23 cm back down, and finally 19 cm back up, so that the cocoon is within 4 cm of the first turnaround point (shown above). Although the larva began feeding last summer, over a third of this length was mined after I collected the branch on May 22.

#35: Gracillariidae sp.  Right after making that discovery about the Marmara larva, I was heading out for a walk when I spotted a sawfly larva munching on a paper birch leaf at the edge of the yard. Leaning in for a closer look, I noticed this underside tentiform mine on a neighboring leaf.

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The larva will either pupate within the mine, revealing itself to be Phyllonorycter martiella, or it will exit to feed externally in a fold at the edge of the leaf, meaning it’s one of several Parornix species I have trouble distinguishing even after the adult has emerged. With any luck, I’ll have an update on this one soon…

#36: Glyphuroplata pluto (Chrysomelidae). Later on June 5 I was mowing a path in a part of the yard I hadn’t gotten to yet, when I stopped just short of running over an unusual grass I didn’t recognize:

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I knelt down for a better look at the grass, which turned out to be some little Dichanthelium (not the large deertongue grass, D. clandestinum, that is common in our yard), and spotted a beetle mine just getting started at the tip of one of the leaves:

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In a backlit view, you can see the larva inside, and you can see that it is depositing all its frass in the mine rather than pushing it out—indicating that it is Glyphuroplata pluto rather than Chalepus bicolor, an adult of which I saw on a nearby clump of deertongue grass a week earlier.

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Yesterday when I was pointing out the mine to Julia there happened to be an adult G. pluto perched on the same clump of grass, but it dropped to the ground and disappeared as soon as I pointed at it, so I couldn’t get a photo. It looked like this though:

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And right next to that clump of grass, along the arborvitae hedge, I noticed mines of two more new leafminer species for this year’s yard list.

#37: Caloptilia fraxinella (Gracillariidae). The young larva makes this epidermal mine on a white ash leaf (Oleaceae: Fraxinus americana) before exiting to feed in a leaf roll, just as with the C. serotinella larvae that are feeding on a nearby black cherry sapling.

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This species overwinters as an adult, and every winter I find at least one on a wall in the house, evidently having been brought in with firewood.

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#38: Calycomyza menthae (Agromyzidae). Several mines of this species are just getting started on the beebalm (Lamiaceae: Monarda didyma).

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The initial narrow, linear portion of each mine will soon be obliterated by a big brown blotch. These larvae feeding now will emerge as adults within a few weeks.

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#39: Liriomyza fricki (Agromyzidae).  And finally, while picking greens in the hoop house for dinner, I found one mine of this species on white clover (Fabaceae: Trifolium repens), already vacated.

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Most Liriomyza species have a quick turnaround, and the larva that made this mine could emerge as an adult any day now.

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And now on to the sawflies! I’ve been seeing all sorts of adult sawflies around the yard, ranging from little black nondescript ones to big colorful ones that resemble ichneumon wasps. But I’m just focusing on larvae here, and in the past week I’ve found four more species, though I’ll have to rear all of them to adults to find out exactly what they are.

Sawfly #3. On May 31 I inspected a bigtooth aspen (Salicaceae: Populus grandidentata) sapling that has popped up in our yard, hoping to find leaf mines of Phyllocnistis populiella. No such luck, but I did find five of these sawfly larvae:

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So far my review of North American sawfly host records has turned up 22 species that feed on poplars. I suspect these are something in the Euura/Nematus department, but have no way of looking them up. That’s why I’m working on a guide!

The next day, all five of the larvae I collected had finished feeding and burrowed into soil to pupate. The adults might emerge in a few weeks or not until next year, depending on who they are.

Sawfly #4. Also on May 31, the same paper birch sapling with the Agromyza mines was covered with these larvae:

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Not quite as striking as the aspen larvae, but they do have distinctive little pink butts:

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By June 4, some of these larvae had spun cocoons between leaves in the peanut butter jar I collected them in. The ones I’ve found wandering and moved to a jar of soil have all opted to burrow down before spinning. So far I know of 18 birch-feeding sawfly species; no idea which one this is.

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As they approach maturity, the fecal pellets of these larvae start to be strung together on strands of silk, presumably because they’re starting to produce silk in preparation for spinning cocoons.

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Meanwhile, on June 1, the Acordulecera larvae I found on red oak had molted to bluish prepupae and were likewise ready to burrow and spin cocoons:

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Sawfly #5. Here’s the larva I found on paper birch on June 5 next to the gracillariid leaf mine—much larger than the above species; also solitary, without the pink butt, and with a distinctive stripe behind its eye.

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When I got back from my walk that had been delayed a few minutes by stopping to collect and photograph this larva, it had molted and lost the stripe on its head.

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I thought it might be done eating, so I put it (along with its leaf) in a jar of soil. But an hour later it was back to munching away, and its stripe was coming back. (In this photo it has a few grains of sand on it from having been dropped in the soil.)

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Sawfly #6. Yesterday evening after dinner, Julia and I were gazing down from the porch at the semi-wild garden with the birch sapling, and I noticed that some of the lady ferns (Athyriaceae: Athyrium angustum) had been nibbled a bit. After staring for a few moments, I spotted a sawfly larva resting on top of one of the fronds. I went out with a camera and a peanut butter jar, hoping to photograph the larva in situ and then collect it for rearing, but as soon as I started to bend down for a photo, it pulled a “stop, drop, and roll” and vanished from sight. I spent several minutes scouring the ground for it, and then gave up and started scouring the fronds to see if I could find another larva, but only found this shed skin:

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Then I realized I had damaged one of the precious wood hyacinths in the process of searching for the larva, and while I was kicking myself for that, I saw the larva looking at me from the top of one of the hyacinth leaves, which it had climbed up in a failed attempt to get back to its host plant.

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Once I had it safely inside, I got some pictures of it on a lady fern frond…

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…and when I was done with that I discovered another tiny larva, presumably a younger example of the same species, wandering around on my photography plate.

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Two sawflies that occur in North America are known to feed on lady fern in Europe. Heptamelus dahlbomi has only been found in British Columbia and is a stem borer, so this obviously isn’t that; Strongylogaster macula has been found in both British Columbia and Ontario (and possibly elsewhere; I’m just going on the information in the 1979 Catalog of Hymenoptera at this point), and the larva shown at the bottom of this page does look similar to my larger one. I’ve never yet managed to rear a fern-feeding sawfly; they need to bore into wood to pupate and then be kept over the winter. We’ll see how it goes this time…

And incidentally, as of yesterday, the Sterictiphora larva I found on May 28 (which I did not collect) was still munching away on the same black cherry leaf, having endured all sorts of weather including a couple of thunderstorms. Its initial “curious winding slit” was long ago obliterated by its subsequent feeding. I took this photo on June 5:

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For the edible plant list, I’ve added three more species since the last post:

59. Canada lettuce (Asteraceae: Lactuca canadensis) – leaves
60. Honeyberry (Caprifoliaceae: Lonicera caerulea) – fruits (the first couple were just barely ripe)
61. Lady’s thumb (Polygonaceae: Persicaria maculosa) – leaves and flowers

The plum curculios (Curculionidae: Conotrachelus nenuphar) have left their marks on a lot of our developing fruits, including this Asian pear:

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Hopefully there are still some fruits left for us this summer and fall. In the past the curculios have caused a lot of plums to drop prematurely, but they need to be thinned out some anyway. It’s the raccoons that do the real damage. Here’s an adult plum curculio I found on the kitchen wall one spring:

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Willow Stem Galls

Swellings on willow stems can be caused by a variety of gall midges, sawflies, agromyzid flies, and buprestid beetles. In many cases I have no clue as to the identity of the gall inducer just from looking at a photo of the gall, so on BugGuide I long ago made a page here for dumping photos of unidentifiable willow stem galls. For my survey of galls and leaf mines of Nantucket, though, “some kind of willow stem gall” wouldn’t cut it, so last September I collected this gall on purple willow (Salix purpurea) to see what would emerge from it.

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When Julia and I returned in November for the biennial Biodiversity Research Conference, we collected several more galls like this from the same clump of willows. They all went into the fridge for the winter, then got taken out along with all the other overwintering bugs in late February.

Between March 10 and 19, four midges emerged from the above gall, leaving their pupal exuviae poking out.

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In Gagné’s* key to midge galls on willows, this gall lands at 12b: “Twig swelling tapered, woody, sometimes barely noticeable”, which is attributed to “Dasineura corticis Felt, Lygocecis spp., Neolasioptera sp., Rabdophaga spp., as well as sawflies.” Although I don’t yet know exactly which (if any) of these options are represented by my midges, with both male and female specimens in hand, I figure I have a pretty good shot at being able to put a name on them eventually.

Towards the end of March, look who emerged from one of the galls we collected in November:

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A sawfly! More specifically, a sawfly in the genus Euura (Tenthredinidae). That used to mean a lot more than it does now; six years ago, phylogenetic studies resulted in numerous other genera being synonymized under Euura**, with the result that over 250 North American species are now placed in this genus—somewhere between a fifth and a quarter of all North American sawflies. I just finished entering all of these species into a spreadsheet as part of my new sawfly larva project, and to my horror I discovered that these synonymies have resulted in eleven secondary homonyms that apparently no one has done anything about. That is, there are eleven pairs of species with identical names, and to make matters worse, six of these pairs have the same author and year. For instance, Marlatt (1896) described Pontania pacifica and Pteronus pacificus, but both species are now known as Euura pacifica (Marlatt, 1896). Although Dave Smith, the American authority on sawflies, was a coauthor on the paper that made these drastic changes, he has continued to use the old genus names, which do provide useful groupings. For instance, Pontania species form closed leaf galls on willows; Phyllocolpa species form simple leaf fold or leaf curl galls on willows and poplars; species of Euura subgenus Gemmura form willow bud galls; and species of Euura subgenus Euura form willow twig and petiole galls. In any case, no matter how you slice it, this sawfly I reared is as Euura as they come.

All that aside, this rearing provides the perfect opportunity to learn how to distinguish midge and sawfly galls made on twigs of the same willow, right? So here’s a side by side comparison:

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That’s right, they’re exactly the same. (The difference in color here is a result of the midge gall being dried out while the sawfly gall is still damp). The only external difference is that in the vacated galls, there are midge exuviae poking out of the midge gall, and the sawfly gall instead has a single relatively large, circular exit hole.

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Because of this, it’s hard to say with confidence what insect was the host of the twelve pteromalid wasps that emerged from the November galls over the course of the next month.

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The first ones appeared on the same day as the sawfly—one even emerging from a smaller hole in the same gall:

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But does that necessarily mean the pteromalid is a sawfly parasitoid? As I understand it, these Euura larvae are always solitary. It may be possible that this individual pteromalid uncharacteristically acted as a true parasite—not killing its host—but it’s also possible that its host was a midge that was either an inquiline in the sawfly gall or happened to initiate an inconspicuous gall at the same point on the stem.

In addition to the dozen pteromalids, a single male Eurytoma (Eurytomidae) emerged from one of the November galls in mid-April.

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The moral of this story is, if you want to find out what kind of willow stem gall you have, you might be able to find out by waiting to see what emerges, but this might just leave you with more questions! Cutting the gall open should help to clarify sawfly vs. midge, but of course if you do this while it’s still occupied then you’ve blown your chance to find out exactly which sawfly or midge.

* Gagné, Raymond J. 1989. The Plant-feeding Gall Midges of North America. Ithaca, NY: Comstock Publishing Associates. 356 pp.

** Prous, Marko, Stephan M. Blank, Henri Goulet, Erik Heibo, Andrew Liston,
Tobias Malm, Tommi Nyman, Stefan Schmidt, David R. Smith, Hege Vårdal, Matti Viitasaari, Veli Vikberg, and Andreas Taeger. 2014. The genera of Nematinae
(Hymenoptera, Tenthredinidae). Journal of Hymenoptera Research 40: 1-69.

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The Yard List(s), Part 9

Things are really picking up now… First of all, I collected something from the arborvitae hedge at the end of the day yesterday that I didn’t get around to investigating until this morning.

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There were two of these little white cocoons attached to the foliage, and I had a feeling they were related to some of the needle mines on those shrubs. This morning I checked my key to Thuja leaf mines, and as I thought, both of the species of needleminers I’ve found in this hedge before—Coleotechnites thujaella (Gelechiidae) and Argyresthia thuiella (Argyresthiidae)—pupate inside their mines. But there are three other species that spin a cocoon outside the mine (also differing from the first two in that they deposit frass within the mine instead of pushing it all outside). Of these three, there is one that spins a white, spindle-shaped cocoon and occurs in northeastern North America: Argyresthia aureoargentella. So that’s miner #17 for this year’s yard list. The only published distribution records I have found for this species are Ontario, Quebec, New Brunswick, and Maine, so this might be the first record from Massachusetts; however, on BugGuide there is a photo of an adult from Pennsylvania, so finding one here isn’t surprising.

When I headed out into the front yard this morning, I decided to check on some of the fruit trees. We have several apples and pears that were sent to us as bare-rooted sticks in the mail six years ago by Julia’s family’s neighbor in Ohio, who has a small orchard and develops his own varieties. On the variety he named “Dave’s delight,” of which I think ours is the only one in existence besides the parent tree, I noticed a stem mine I hadn’t seen before (this photo is rotated 90 degrees):

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It didn’t seem to go anywhere from there, but I checked the other side of the tree and found not only a much longer mine, but the characteristic Marmara bark flap under which the cocoon is spun:

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So I raced back inside to get some forceps and a vial, and very carefully peeled back the flap, revealing an intact cocoon:

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With any luck, I’ll have an adult Marmara elotella (Gracillariidae) within a few weeks. So that’s #18. Additional species piled up as I slowly made my way around the yard…

#19: Orchestes mixtus (Curculionidae). This weevil is essentially identical to O. pallicornis (shown on black cherry in my previous two posts), but feeds on plants in the birch family (Betulaceae). Today I found mines on our cultivated hazelnut, variety “Medium Long,” which is believed to be a hybrid of the European Corylus avellana and the native C. americana.

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I also found one on black birch (Betula lenta) that was a little further along:

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#20: Sumitrosis inaequalis (Chrysomelidae). I saw several adults of this species, whose larvae mine leaves of various plants in the aster family (Asteraceae). Most of them were resting on rough-stemmed goldenrod (Solidago rugosa). These beetles overwinter as adults, like their fellow hispine (tribe Chalepini) Chalepus walshii that I wrote about yesterday.

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#21: Marmara ?fulgidella (Gracillariidae). These mines are in the bark of our young Chinese chestnuts (Fagaceae: Castanea mollissima). Marmara fulgidella was described from adults reared from oak, and mines later found on American chestnut (C. dentata) were assumed to be made by the same species but this has not been proven. In fact, it seems certain that there is a different species on chestnut, because M. fulgidella spins its cocoon outside the mine, and Dave Wagner has found mines on American chestnut with the cocoon under a bark flap as in M. elotella and M. fraxinicola*. I wasn’t able to tell for sure whether any of these Chinese chestnut mines were still occupied, but I didn’t see any bark flaps.

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#22: Japanagromyza viridula (Agromyzidae). I found several mines just getting started on a red oak (Fagaceae: Quercus rubra) sapling. 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).

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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.

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

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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.

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One black birch (Betulaceae: Betula lenta) sapling had a number of mines like this, which as I explained the other day are characteristic of casebearer moths (Coleophoridae: Coleophora). I spent quite a while searching for the larva(e) responsible for these mines before suddenly spotting two at once—and they were two different species!

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#23: Coleophora comptoniella (Coleophoridae).  There are two birch-feeding species that live in a “spatulate” case with a bivalved apical opening; the larger (~1 cm) case rules out C. lentella.

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Check out the second half of this post to see what this larva was up to last fall. And here’s an adult of Coleophora comptoniella I reared from paper birch (B. papyrifera) last spring:

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#24: Coleophora serratella (Coleophoridae). This species is recognized by its smaller, trivalved case.

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#25: Pegomya rubivora (Anthomyiidae). This one is mostly a borer (feeding in deeper tissues of the stem, where its tunnel is not externally visible), but the young larva mines a spiral around the shoot, girdling it and causing it to droop.

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A close-up of the spiral mine:

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This is a stem of black raspberry (Rosaceae: Rubus occidentalis). I first met this fly last June in Vermont, where a whole patch of black raspberry was similarly affected. I collected a bunch of stems and had a single adult emerge this spring:

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#26: Agromyza aristata (Agromyzidae). A small American elm (Ulmaceae: Ulmus americana) at the edge of my yard had three mines of this fly. This is yet another species that appears only in the spring, overwintering as a pupa.

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#27: Marmara n. sp. (Gracillariidae). That same elm had bark mines of Marmara #5 for my yard; this is a species that has been reared but has not yet been described and named.

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#28: Phytomyza solidaginophaga (Agromyzidae). This species had been conspicuously missing from my spring leafminer lineup, and I had been specifically looking for it for the past couple of weeks. Finally I found three mines on Canada goldenrod (Asteraceae: Solidago canadensis) at the end of my long walk around the yard; they were already empty, as they should be: This species appears only in mid-May in Massachusetts, and that is the only way I know to distinguish its mine from that of P. astotinensis, which can be found from June to October.

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Then this afternoon, when I finished mowing some paths through our meadowy lawn, I inspected a clump of deertongue grass (Poaceae: Dichanthelium clandestinum) and found three more species!

#29: Cosmopterix gemmiferella (Cosmopterigidae). What actually caught my eye at first was this narrow, pale stripe, which turned out not to be a mine (I’m not sure what caused it):

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But the tip of the leaf happened to be twisted in such a way that it revealed the characteristic pupation mine of C. gemmiferella. This species apparently overwinters as a larva in the plant’s basal rosette, mining the leaves into early spring. When finished feeding, the larva exits its mine and moves up to one of the lower stem leaves, in which it makes a short, inconspicuous mine, where it spins its cocoon. In the close-up below, you can see where the larva entered the leaf at upper right, and its cocoon is the elongate white patch at lower left.

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This species has previously only been found on much smaller-leaved Dichanthelium species. Here is one I reared from D. acuminatum, found in the woods behind my house:

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#30: Leucospilapteryx n. sp. (Gracillariidae). Not 20 feet from the mines of the undescribed Marmara on elm was a leaf mine of another undescribed moth species. Dave Wagner told me once that it belongs to an undescribed genus, but the adult always looked like a Leucospilapteryx to me, and Don Davis has it listed in that genus in a list of Gracillariidae he shared with me last fall, so that’s what I’m calling it for now. It makes an underside tentiform mine like some of the ones on black cherry made by Caloptilia serotinella (a few posts back).

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This larva recently finished its “sap-feeding” stage, in which it fed in an epidermal mine visible only on the lower leaf surface; it has now begun to consume the mesophyll and spin silk that causes the leaf to buckle. A backlit photo reveals the shape of the larva inside:

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#31: Chalepus bicolor (Chrysomelidae). Both adults and larvae of this species are apparently specific to grasses in the genus Dichanthelium, whereas C. walshii feeds on a number of grass genera but is very rarely found on Dichanthelium. Adults of C. bicolor feed in a similar way to C. walshii but don’t make those neat rectangular patches.

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Although I was confident that this was feeding sign of C. bicolor, I checked some other patches of deertongue grass until I finally saw an adult. It was feeling skittish and only allowed me to get one blurry photo:

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So here’s a better one, from the archives:

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Today’s yard exploration also turned up sawfly larva #2 for the season, feeding in small groups on red oak leaves:

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I’ve reared similar larvae to adults a few times, and they belong to the Acordulecera dorsalis complex (Pergidae)—a confusing group of species that no one has gotten around to sorting out yet. The adult below was collected as a larva on red oak at the 2016 Connecticut BioBlitz and emerged as an adult the following spring (this is why it takes me a while to finalize my lists for bioblitzes):

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As for the edible plants list, it looks like it will soon be eclipsed by the leafminer list, but I added three more today:

56. Staghorn sumac (Anacardiaceae: Rhus typhina) – branchlets
57. Fox grape (Vitaceae: Vitis labrusca) – tendrils
58. Apple mint (Lamiaceae: Mentha suaveolens) – leaves (tea)

It never would have occurred to me to eat sumac branchlets, but one of Arthur Haines’ books describes how you can peel off the bark of tender young shoots and eat the cores, so I gave it a try. They were pretty tasty.

* Eiseman, Charles S., Donald R. Davis, Julia A. Blyth, David L. Wagner, Michael W. Palmer, and Tracy S. Feldman. 2017. A new species of Marmara (Lepidoptera: Gracillariidae: Marmarinae), with an annotated list of known hostplants for the genus. Zootaxa 4337(2): 198–222.

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The Yard List(s), Part 8

You may recall that back in early April I said that this year I would be listing not just the leafminers and edible plants I find in my yard, but also the sawfly larvae. So ever since I spotted the Monoctenus female laying eggs in the arborvitae hedge along the road, I’ve been checking every couple of days or so for her offspring munching away on the needles. No luck so far, but on today’s trip to the hedge I did see my first sawfly larva of the year—not on the arborvitae but on a black cherry sapling growing right next to it. Julia was able to guess what I’d found right away, with no other information than that I had found a sawfly larva, combined with my level of excitement at having found it:

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Yes, Sterictiphora, eating its characteristic “curious winding slit” into the leaf, as first described by Harrison Dyar back in 1897. I wrote about my first encounter with one of these in June 2013, and in May 2015 I shared some more examples, including photos of the adult S. serotina I reared from that first larva. This one in my yard may or may not be S. serotina; there are six Sterictiphora species in North America, and at least four of them feed on Prunus species (though one is known only from the western US). Sterictiphora prunivora feeds on both Prunus and AmelanchierS. sericea had no known hosts until I reared one from Amelanchier last year*; and S. transversa (with the curious distribution of Alaska, Alberta, and Maryland) still has not been associated with any plant.

Here’s a closer view of today’s larva (the field of view here is 11 mm wide):

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On a neighboring branch of the same black cherry sapling was a female Orchestes pallicornis. Just yesterday I wrote about having seen this species in my yard, and said that “Soon, females will be inserting eggs along the midribs of leaves, and the larvae will form linear mines extending toward the leaf tips.” Well, there she was, chewing her third oviposition hole in the midrib of a leaf at the tip of the branch:

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I don’t think I’ve ever actually witnessed this before, so naturally I spent a while watching her, in between bouts of admiring the Sterictiphora‘s sinusoidal splendor. Two minutes after I first noticed her, she turned around and began inserting an egg in her most recent hole.

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Wow, I didn’t think I had sat there for that long, but according to the time stamps on the photos, it was 36 minutes later that I took this picture of her excavating a fourth hole:

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If you look closely you can see the dark spot where her little black schnoz is buried in the midrib. And here she is inserting an egg in that same hole:

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While I sat there entranced by these two tiny bugs doing their thing, I suddenly noticed that this cherry sapling had several bark mines on it:

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Since the mines are on a black cherry, we know that they were made by a larva of the moth Marmara serotinella (Gracillariidae)—miner #16 for this year’s list. If you read yesterday’s post, you’ll remember that I have a white ash branch in a vase on my kitchen counter being mined by a larva of M. fraxinicola. Yesterday I wrote that “Over the past ten months or so, the larva mined 22 cm toward the tip of the branch, then turned around and mined 20.5 cm back down.” Amazingly, as of right now (~27 hours later), it has lengthened the downward mine to 23 cm and turned around once again, mining 5 cm back up the branch. Clearly Marmara larvae pick up the pace as they reach maturity.

And finally, since yesterday’s post, I was able to add one more species to the “plants I have eaten” list:

55. Strawberry (Rosaceae: Fragaria × ananassa) – fruit

The strawberries in the open-air gardens are in flower right now, but we have a few in our hoop house that got going early. I would have gotten to add strawberry to the list a few days ago, but some little rodent devoured the first two fruits just as they were developing a blush of red. I then placed inverted jars over the three ripest remaining fruits, and that provided adequate protection from the buck-toothed bandits to allow them to turn solid red.

Oh, and on my way back to the house from the photo session, I spotted another Sterictiphora larva on a different black cherry sapling. Can’t get enough of these little cuties.

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* Eiseman, Charles S. and David R. Smith. 2020. New sawfly (Hymenoptera: Argidae, Tenthredinidae) host records from northeastern North America. Proceedings of the Entomological Society of Washington 122(2): 299–307.

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The Yard List(s), Part 7

Last night I finished revising and updating the Lepidoptera chapter for the second edition of Leafminers of North America, and when I got to the end I was reminded that some species of Leucania (like the ill-fated one I wrote about earlier this month) start out life mining in blades of grass. Yes, even big ol’ noctuids can be leafminers. There’s no escaping them.

Anyway, it’s been nearly a week since my last post, and in the meantime several more miners have appeared in my yard.

#12: Marmara fraxinicola (Gracillariidae). On May 22, Julia and I were cutting some saplings from the edges of the yard for use in our new tomato infrastructure, and at the top of a 15-foot white ash (Oleaceae: Fraxinus americana) sapling was this fresh-looking stem mine:

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It can often be difficult to trace a Marmara mine from beginning to end, but because this mine was made recently and because this species mines throughout its development in the outermost layer of bark, following this one was a piece of cake.

The transparent shell of the egg that was deposited early last summer is visible at one end…

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…and the yellowish larva, still feeding away in the bark, is visible at the other end.

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It’s admittedly harder to see than the larva of a leafminer, but it’s there all right, in the upper left corner of the above photo. This is actually within 2 cm of the eggshell, but on the other side of the branch. Over the past ten months or so, the larva mined 22 cm toward the tip of the branch, then turned around and mined 20.5 cm back down. The branch is currently sitting in a vase on the kitchen counter where I can keep an eye on it. I’ve never tried to rear this species before, but it is one that, like Marmara viburnella, spins its cocoon under a bark flap excised at the end of the mine, so I don’t have to worry about the larva wandering off or drowning in the water in the vase.

The next three species came in the form of adult beetles, and since I wasn’t carrying a camera when I saw them, I’ll illustrate them with photos from past years.

#13: Orchestes pallicornis (Curculionidae). On May 23 I spotted this weevil nibbling on a leaf of black cherry (Rosaceae: Prunus serotina) at the edge of the yard.

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Like Dibolia borealis, this flea weevil has a single generation per year, with larvae feeding in spring or early summer and with adults overwintering. Soon, females will be inserting eggs along the midribs of leaves, and the larvae will form linear mines extending toward the leaf tips.

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Older larvae form blotch mines and then spin circular cocoons in which to pupate. Here is a communal mine with three cocoons inside:

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#14: Chalepus walshii (Chrysomelidae). Yesterday morning when I went to pick some pokeweed shoots for lunch, I found an adult of this beetle perched at the tip of a blade of reed canary grass (Poaceae: Phalaris arundinacea).

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A few inches below it was one of the characteristic rectangular feeding patches I illustrated here. This is another species that has a single generation and overwinters as an adult, but C. walshii larvae can be found later in the season than those of D. borealis and O. pallicornis. Reed canary grass wasn’t known to be a larval host of C. walshii until I found some mines in my yard last July and reared a couple of adults from them.

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This is immediately recognizable as a Chalepus mine because of the characteristic brown egg covering near the tip of the leaf, as well as the dark brown frass expelled from the leaf margin.

#15: Brachys aerosus (Buprestidae). Yesterday afternoon I spotted this species nibbling on the edge of a red oak (Fagaceae: Quercus rubra) leaf.

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Once again, this is a leaf-mining beetle with a single generation per year, but Brachys species overwinter as larvae within their mines rather than as adults. They pupate once the weather warms up, and the adults emerge about a month later. Eggs are laid in summer, but the larvae take their time, and they can still be found feeding in late October, as in this example (the larva is at far right):

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In contrast, the Aulagromyza cornigera larva that appeared on May 18 had already exited its mine when I checked on May 22:

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On May 23, I went to check on the Caloptilia serotinella larva I’d found two days earlier. It had crossed the midrib, but otherwise hadn’t made much progress.

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Actually, looking at the photo now, I can see that the larva crossed back over the midrib and exited through a hole in the epidermis just below the midrib, to the left of the frass line. So it turns out this species will sometimes make an entirely linear mine, rather than the linear-blotch mines I usually see.

In any case, as I arrived at that black cherry sapling, the wind happened to blow a neighboring leaf in such a way that I noticed a similar mine that was only visible from the lower surface.

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I believe this is another C. serotinella mine. Some Caloptilia species aren’t particular about which side of the leaf they mine.

The next day, silk spun by that larva within the blotch portion of the mine had caused the mine to buckle and become “tentiform.”

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And once again, now that I look at the photo on the big screen, I can see the larva had already exited at this point—the hole is at the far left end. But not having noticed this yet, I went back one more time yesterday to check on the mine’s progress, and the leaf had now completely folded over, concealing the blotch.

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Having seen these exit holes, I had to dash out into my yard just now—flushing a gorgeous male indigo bunting from the dandelions by the front door—and verify that yes, the larvae have now formed neighboring leaves into conical shelters in which to complete their feeding, as Caloptilia larvae should.

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I think we’re all caught up now, in terms of leafminer happenings in my yard… Meanwhile, I’ve partaken of another four edible plants from the yard since last time:

51. Common milkweed (Apocynaceae: Asclepias syriaca) – shoots
52. Riverbank grape (Vitaceae: Vitis riparia) – leaves
53. Wild leek (Amaryllidaceae: Allium tricoccum) – leaves
54. Pokeweed (Phytolaccaceae: Phytolacca americana) – shoots

Just in case anyone reading these posts is inspired to go out and try the plants I’ve been listing: please do some research first! The shoots of both milkweed and pokeweed, for instance, require boiling for seven minutes or so before eating, or you’ll be sorry. I’d never tried pokeweed before, but it turns out to be delicious, as advertised—somewhat similar to asparagus. Milkweed is also quite good, and don’t worry, there is plenty left for the monarchs, and the milkweed tussock moths, and the large and small milkweed bugs, and the milkweed long-horned beetles, and the milkweed weevils, and the milkweed leaf-mining flies—all of which are equally deserving of our affection and it drives me nuts when people want to kill or remove any non-monarch organism they find on their milkweed plants. If you simply refrain from mowing your lawn, you will soon have more than enough milkweed to suit everybody’s needs. We got enough from weeding a few strawberry and asparagus patches yesterday to provide the main vegetable for last night’s stir fry and this morning’s omelet, and new shoots keep popping up faster than we can pick them.

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The Yard List(s), Part 6

First of all, check out this lovely rhodora (Ericaceae: Rhododendron canadense):

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This is a shrub of bogs and other wet habitats that I don’t get to see very often—or didn’t until now. I picked this one up last fall at a local native plant nursery, and it’s now happily blooming in the ever-shrinking lawn next to my house.

Second, I have some updates on the “leafminers of my yard” front. As you may recall, three days ago I found this Aulagromyza cornigera mine on one of our honeyberry bushes:

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As of today there still seems to be just the one mine, but that larva has made some good progress:

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When I took these photos, there was a braconid wasp lurking on a nearby leaf, so this larva may be in trouble…

Meanwhile, as of today leafminer species #10 and #11 have appeared in the yard. One was the miner I was anticipating finding next, and I’ve been checking the blackberry plants (Rosaceae: Rubus allegheniensis) every day for it, but as it turned out I wasn’t even looking for it today when I noticed two of the brownish blotch mines. I couldn’t find the larva at first, but when I came back with a camera and grabbed the plant to tilt it to a good angle for photographing one of the mines, I almost squished the larva between my thumb and forefinger.

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At right in the above photo is the characteristic blotch mine of a casebearer moth (Coleophoridae: Coleophora), with a round entrance hole on the lower surface through which the larva extended the front of its body to feed without leaving its portable house. At left is the larva in its case, pretending to be a bud. Here’s a closer look:

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The case is made of silk and pieces of blackberry leaf, and the larva has been adding to it periodically as it grows. The whitish nubbin at the top is the larva’s tiny initial case, which it constructed sometime last year.

In this backlit view of the mine, you can see that the mine is full-depth (all the tissue between the two epidermises has been eaten), and that it is totally clean: the larva keeps its tail end in the case while mining, and periodically backs up to the tip of the case when it needs to get rid of some frass.

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Because it’s feeding on blackberry, we know this casebearer is Coleophora cretaticostella. As it happens, I have reared this species just once, from a larva collected about 50 feet away from today’s larva, six years ago to the day. In fact, my photos of the first larva were taken six years to the minute before I took these photos. The adult emerged at the end of June:

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I found leafminer #11 at the opposite corner of the yard, on a black cherry (Rosaceae: Prunus serotina) sapling that started out as a fox scat full of cherry pits deposited in the lawn, also about six years ago. This is another mine I happened to spot out of the corner of my eye as I was walking by.

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Today’s finds are a good illustration of the diversity in leaf mines. The Coleophora mine is a full-depth blotch with no frass inside; this second one is an epidermal linear mine with a continuous line of frass down the middle. In an epidermal mine, the larva is feeding within the thin epidermal layer just below the leaf cuticle, drinking the cells’ liquid contents but not consuming any tissue—which is why in the backlit view there is no difference in transparency between the mine and the surrounding tissue. Mines like this are characteristic of the moth family Gracillariidae. I have found no mention in the literature of gracillariid mines on cherry that start out with a long linear portion. However, I have found these mines many times before, on both black cherry and choke cherry (P. virginiana). When complete, the mines are blotchy at the end, as in this example on choke cherry:

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Here’s another example, in which the blotch portion has caused the leaf to curl, partly concealing it:

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Terry Harrison has reared adults from mines like this in Illinois; they are the “Parornix sp. 2″ pictured here.

The weird thing is, after several years of failed attempts, I managed to rear adults from several different collections of these mines in July 2018, and all of them turned out to be Caloptilia serotinella rather than Parornix. Unfortunately they emerged while I was on a road trip and I didn’t get to photograph them alive, but here’s an adult of the same species that I found on my wall in December 2018—presumably brought in with firewood:

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The leaf mine of Caloptilia serotinella has not been described in the literature, but when C. R. Ely described the species in 1910, he noted that the mature larva folds the tip of the leaf over to form a hollow tetrahedron. The vast majority of Caloptilia species similarly abandon leafmining as older larvae and construct a leaf roll of some sort in which to finish feeding.

…And finally, this week has brought the number of plant species I’ve eaten from my yard up to 50:

48. Red clover (Fabaceae: Trifolium pratense) – leaves
49. White clover (Fabaceae: Trifolium repens) – leaves
50. Wild sarsaparilla (Araliaceae: Aralia nudicaulis) – shoots

I’d never tried any of these before this spring. It turns out that young clover leaves are high in protein and perfectly palatable if cooked for a few minutes. And tender shoots of wild sarsaparilla are pretty tasty; as Arthur Haines notes, eating a lot of them raw produces a mild irritation in the back of the mouth, but a little cooking takes care of this. This morning we had some in an omelet, along with winter cress, tower mustard, stinging nettle, curly dock, clover, and other goodies—all collected on the way to the garden, to which I never made it because I had all the food I needed before I got there.

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The Yard List(s), Part 5

Back on May 5, spring was cooking along; flowers were opening on the Virginia bluebells that I had completely forgotten we had planted among the ostrich ferns under the old apple tree last year.

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But a few days later we had a setback, in the form of some snow that fell on the night of the 8th, into the morning of the 9th.

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The snow melted away, but then we had a couple of frosts, which presented even more of a threat to the flowers and tender young leaves that had just opened up. The last one (I’ve decided it was the last one) was on the morning of the 14th. Amazingly, the flowers made it through all this pretty much unscathed, which was especially surprising with the peaches.

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We tucked the asparagus patch in with blankets each night, which turned out to be worthwhile, since the two stalks we missed on the first night got frostbitten and turned to mush. Otherwise, the main casualties were the sensitive and interrupted ferns in the woods; some maple leaves will end up a little disfigured but have now resumed expanding. Spring is now back in full swing, and everywhere are new leaves presenting blank canvases for leafminers and other leaf-feeding insects to make their marks.

One plant I’ve been watching closely is the honeyberry (Caprifoliaceae: Lonicera caerulea), because this and other honeysuckles are the hosts for Aulagromyza cornigera (Agromyzidae), one of the first leafminers to show up apart from those that overwinter as larvae. This afternoon, there it was: a lone A. cornigera larva etching its characteristic white trail with discrete black frass grains.

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In just a few days, the mine will be complete…

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…and the larva will pop out of the leaf, drop to the ground, and form a puparium…

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…not emerging as an adult until next spring.

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So that brings the “leafminers in my yard” total to nine so far this spring. It is the first one to arise from an egg laid this year, not counting the Chrysoesthia sexguttella mines that are now becoming abundant on the lambsquarters in the hoop house. Those larvae are the progeny of adults that emerged in early April, but I didn’t see an adult of that species outside the hoop house until last week, so they are more than a month ahead of schedule.

In my first post about the leafminer yard list, I said there were larvae of both Argyresthia thuiella (Argyresthiidae) and Coleotechnites thujaella (Gelechiidae) overwintering in the arborvitae hedge along the road. I said this with confidence because there are mines all over the trees; although the mines of the two species are indistinguishable, I have seen adults of both on that hedge, and I have reared C. thujaella from some of the mines. The truth is, though, I have never found a definite mine of A. thuiella there or anywhere else, and I’ve been watching this spring to see if I can spot some larvae. Although the mines of the two species are identical, they can be identified when larvae are present because A. thuiella larvae are green while those of C. thujaella are brown. Today I finally noticed some fresh, whitish mining extending out from the old, brown mines that were made last fall.

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(The difference was more apparent to my eyes than to my camera’s sensor.) But alas, every mine I photographed with bright backlighting had a brown larva inside. The green larvae of A. thuiella remain elusive.

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For a consolation prize, I found this sawfly laying eggs in some of the needles.

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I surmised based on the host plant that she belongs to the genus Monoctenus (Diprionidae), which Dave Smith confirmed. There are at least three Monoctenus species in eastern North America, but there is no key that can be used to identify them. Dave says, “The genus needs study.  The one in the Northeast is usually called M. suffusus,  I’ve called the one I get around here [northern Virginia] M. melliceps.  I’ll have to wait till I get back to the Museum [the Smithsonian, which of course is closed due to COVID-19] to check. One would think this might be an easy project, but it will take a lot of dissecting saws [ovipositors] and male genitalia.” For what it’s worth, M. suffusus is the only name that has been linked to arborvitae (Thuja occidentalis); this species has also been reported to feed on eastern redcedar (Juniperus virginiana). Monoctenus melliceps (which also occurs in Massachusetts) has not been associated with any host, and M. fulvus (a midwestern species) has only been reported from eastern redcedar. I’ve never seen a Monoctenus larva, but I’ll be watching for them now. My only previous experience with Monoctenus was having a male emerge from an arrowwood plant Julia and I had dug up, potted, and bagged in a failed attempt to rear adults of the stem-mining moth now known as Marmara viburnella.

And on the foraging front, the last couple of weeks have added several more plants from the yard to our menu:

36. Rhubarb (Polygonaceae: Rheum × hybridum) – petioles
37. Asparagus (Asparagaceae: Asparagus officinalis) – shoots
38. Watercress (Brassicaceae: Nasturtium officinale) – leaves
39. Bull thistle (Asteraceae: Cirsium vulgare) – roots
40. Lesser burdock (Asteraceae: Arctium minus) – roots
41. Sea kale (Brassicaceae: Crambe maritima) – leaves
42. Maple-leaved goosefoot (Amaranthaceae: Chenopodiastrum simplex) – leaves
43. White sweet clover (Fabaceae: Melilotus albus) – leaves
44. English plantain (Plantaginaceae: Plantago lanceolata) – leaves
45. Jewelweed (Balsaminaceae: Impatiens capensis) – leaves
46. Groundnut (Fabaceae: Apios americana) – tubers
47. Ostrich fern (Onocleaceae: Matteuccia struthiopteris) – fiddleheads

I’ve only tried groundnut a couple of times in the past because it’s usually hard to dig up and there is no guarantee that the tubers will be big enough to make it worth the effort. However, we’ve allowed the plants to spread into our main strawberry patch over the past few years, with the result that we got several meals’ worth simply by weeding the strawberries this week. They’re delicious, with a flavor somehow halfway between peanut and potato.

 

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52 Wasp Pickup

Back on April 7, Noah stopped by to get some eggs and some seeds for his vegetable garden. Just as he arrived and Julia was walking up to meet him, she spotted a caterpillar with a tiny wasp on it. I dashed into the house to grab my camera, and the wasp was still hanging around when I returned.

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Amazingly enough, the wasp still clung to the caterpillar after it was picked up and placed on the driveway for a better view.

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The caterpillar proceeded to go running across the driveway at a steady clip, so it is somewhat miraculous that I was able to get a few sharp close-ups of the 1.5-mm eulophid wasp.

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Now, I was assuming the wasp was inserting eggs in the caterpillar, but as I reviewed the photos on my camera after the wasp finally flew away, I realized she had actually been laying eggs on the surface.

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Twenty-six of them, to be precise. (One of them is obscured in the photo below, but see the following photos if you want to check my math.)

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So naturally I scooped up the caterpillar once more and put it in a jar so I could chronicle the development of the wasp’s progeny. To do this, I’d need to keep the caterpillar fed. All I knew was it was some kind of owlet moth (Noctuidae), but Sam Jaffe of The Caterpillar Lab recognized it as a middle instar Leucania species. He said if I could rear it through another instar or two it might be possible to narrow down the species possibilities. I wasn’t sure how much time this caterpillar had left, but I gathered from the Wagner et al. guide to owlet caterpillars that Leucania species are generalists on trees and shrubs, none of which had leafed out yet, so I collected an assortment of leaves from around the yard and hoped for the best. The caterpillar became pretty inactive and didn’t seem to have much of an appetite, but it ultimately munched a bit on some dewberry and strawberry leaves.

The next day, the caterpillar had contracted, and I thought maybe it was getting ready to molt. Would it be able to shed the eggs before they hatched?

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The eggs had already darkened noticeably.

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The following day, the caterpillar had stretched back out, without having molted.

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With the caterpillar sitting still and with its skin unwrinkled, I was able to get a photo clearly showing all 26 eggs.

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On April 12, nothing much had changed.

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On April 15, the eggs had begun to split open.

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On April 18, the caterpillar had become very active again. The white larvae were now mostly emerged from their darker eggshells, but had not moved away from them. I presume their mouthparts were now latched onto the caterpillar, so it was understandable that it had become a bit restless.

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The next morning, I was surprised to find the caterpillar dead, with 26 fuzzy white cocoons spun on a nearby strawberry leaf.

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But these were braconid cocoons! The poor caterpillar already had 26 braconid larvae living inside it when that eulophid wasp showed up to lay another 26 eggs on it. The eulophid larvae still clung to the caterpillar’s corpse, which was now riddled with dark spots where the braconid larvae had emerged.

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I kept the caterpillar to see if the eulophids would be able to keep developing now that their host was dead. They had grown considerably by the next day (April 20).

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On April 21, none had grown further and several of them had begun to shrivel up. Mold had also started to grow on the caterpillar.

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On April 24, a few were still hanging onto life, but still weren’t growing any.

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A few days later, the caterpillar was consumed with mold, and all hope was lost for these few lingering larvae. I believe these eulophids belonged to the genus Euplectrus, the larvae of which continue to feed in a tight cluster throughout their development, turning a striking bluish color when mature*:

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When finished feeding, Euplectrus larvae disperse and spin a mass of loose cocoons—which could easily be mistaken for mold growth—beneath the remains of their host caterpillar.

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Anyway, on May 4, all 26 of the braconid wasps emerged from the cocoons that had appeared on April 19. They were very zippy but I managed to get a few decent photos.

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They belong to the subfamily Microgastrinae, and I’m guessing the genus Cotesia. Someday, when the staff at the Canadian National Collection of Insects are allowed to go back to work, I’ll send them to José Fernández-Triana and he can tell us exactly what they are. Assuming they have a name.

I suppose now is a good time to follow up on this post from eight years ago that included a pile of Cotesia cocoons with a sprinkling of Eulophus pupae on top—evidently the result of a second wasp ovipositing on an already parasitized caterpillar before it was too late for both sets of offspring to complete their development.

I collected this in September 2012, and the wasps emerged the following spring—a dozen or so Eulophus between April 28 and May 11…

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…and about 20 Cotesia between May 6 and 23.

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From one of the Cotesia cocoons, a hyperparasitoid emerged—an ichneumonid in the genus Itoplectis.

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Whether the mother of the Itoplectis laid an egg in the Cotesia cocoon or had to locate a Cotesia larva within the host caterpillar, I don’t know. Either way, these were two unlucky caterpillars.

* Added 5/6/2020: The Caterpillar Lab has been rearing similarly parasitized Leucania pseudargyria / ursula caterpillars this spring, and these particular Euplectrus larvae are evidently pale yellowish throughout their development, turning a little pinkish when mature.

 

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The Yard List(s), Part 4

May has started off with a string of beautiful, sunny days, and more new birds have been announcing their arrival each day. On the 1st it was the blue-headed vireo; on the 2nd a ruby-throated hummingbird joined the myriad bees, wasps, and flies buzzing around the plum trees that had just burst into bloom, while a blue-gray gnatcatcher wheezed from the trees around the edges of the yard; yesterday the morning started off with the song of a black-throated green warbler, followed before long by ovenbird, common yellowthroat, black-and-white warbler, chestnut-sided warbler, gray catbird, eastern towhee, and barn swallow; and this morning a rose-breasted grosbeak and Baltimore oriole have already joined the chorus (those two always seem to arrive together).

Amid all these arrivals, the season’s eighth leafminer species has made its presence known in my yard: plantain flea beetle (Chrysomelidae: Dibolia borealis). As with the Chrysoesthia sexguttella that are still swarming inside the hoop house, it is the adults rather than the leaf-mining larvae that are now appearing. Unlike those moths, though, these beetles are not newly emerging from pupae; they have been hunkered down as adults since early last summer. I woke up this morning thinking how odd it is that the tiny beetles that are now nibbling the plantain leaves in the lawn were already adults last July when we bought the little fuzzy day-old chicks that are now full-grown hens, laying enough eggs every day to feed me and Julia as well as several neighbors.

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After nibbling on plantain leaves for a few weeks, the beetles will begin laying eggs on them, and in June the trails of the larvae mining inside them will be obvious.

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When full-grown, the bright yellow-orange larvae will exit their mines and burrow into the ground to pupate, emerging as adults in July.

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The new adults may nibble on plantain leaves for a little while, but soon they will go into hiding until the following spring.

Dibolia borealis is among that small minority of native North American species that have become more common and widespread since Europeans arrived here. Over five hundred years ago, they would have fed only on the native Plantago species, which are spotty in their distribution. But they have expanded their diet to include the European P. major, which is now ubiquitous in lawns and other disturbed areas. In Helen Reed’s study of this species at Cornell University nearly a century ago*, she stated that both adults and larvae of D. borealis appear to feed exclusively on P. major, although she found that captive larvae would mine into leaves of another European import, P. lanceolata, when given no other choice. I did find a single mine on P. lanceolata in my yard three years ago, but it is clear that this is not a preferred host.

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Meanwhile I, adaptable creature that I am, have so far eaten 35 different plant species in my yard this spring. The latest additions:

31. Tall blue lettuce (Asteraceae: Lactuca biennis) – leaves
32. Carrot / Queen Anne’s lace (Apiaceae: Daucus carota) – roots
33. Virginia waterleaf (Hydrophyllaceae: Hydrophyllum virginianum) – leaves
34. Tower mustard (Brassicaceae: Turritis glabra) – leaves, flowers
35. Shepherd’s purse (Brassicaceae: Capsella bursa-pastoris) – leaves, flowers, fruits

Asparagus, you’re next!

* Reed, Helen. 1927. Some observations on the leaf-mining flea-beetle Dibolia borealis Chevrolat. Annals of the Entomological Society of America 20(4): 540–549.

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