Things are starting to wind down here in central New England, plant-wise, but I’ve managed to add a couple more leafminers and one sawfly larva to the yard list since the beginning of October. Also several parasitoids have emerged, unfortunately from mystery miners I was hoping to rear to adults.
For instance, on October 1 or 2, this eulophid (a Chrysocharis, I’m pretty sure) emerged from one of my few puparia of the unknown Liriomyza on amaranth (leafminer #181).
And at the same time, this opiine braconid emerged from one of the few intact puparia I found of the unknown stem-mining Ophiomyia on Queen Anne’s lace (#179):
Leafminer #204: Aulagromyza luteoscutellata (Agromyzidae), on Morrow’s honeysuckle (Caprifoliaceae: Lonicera morrowii). On October 7 Julia and I were pulling up some unwanted plants along the boundary with the ATV neighbor and I found one mine that can be attributed to this species with reasonable confidence—it certainly isn’t A. cornigera, the only other honeysuckle miner I’ve found in the yard this year (#9). An ant or some other predator had chewed the larva out of the leaf before it could finish mining.
On October 10 I found this perplexing pair of mines on a red oak sapling behind the chicken house:
So far the mines were entirely linear, suggesting a Stigmella rather than an Ectoedemia, but the known oak-feeding Stigmella species have larvae that are either distinctly yellow or distinctly green. The only one I know of that has a larva with a central row of ventral dots like these is S. altella, which (in addition to having a yellow larva) forms a strictly lower-surface mine, whereas these mines were on the upper surface. (Stigmella altella does appear only October, though, and it’s one of the species I was hoping to find in my yard this month.)
On October 13, I found one of the larvae flailing about on the paper towel in the bottom of the jar, now mottled with pink and orange…
…and the other had spun a white cocoon on the side of the jar—further evidence that these weren’t Stigmella altella mining the wrong side of the leaf; that species has a brown cocoon.
Here are the completed mines:
The way the frass is scattered along the full width of the mine is reminiscent of Stigmella nigriverticella, which has a bright green larva. This prompted me to take another look at my photos of Leafminer #148, which I’d asserted was S. nigriverticella but has been bugging me all summer because the frass is much more densely packed in mines of that species. Also, now that I actually look at this confirmed S. nigriverticella mine from Nantucket, I’m reminded that that species has a much narrower and much more evenly widening mine:
I have little doubt now that Leafminer #148, whose mines I found already empty at the end of July, is the same mystery species I just collected by the chicken house. Here are the July mines for comparison:
All four of these mines share a feature that I don’t remember seeing in any other nepticulid mine: a short, dense, narrow central line of frass right before the frass starts to be scattered broadly across the width of the mine. All four of the mines also begin with an egg laid next to a major vein on the upper leaf surface and end with an exit hole in the lower surface. Is this a previously unknown species of Stigmella or Ectoedemia? One of those, I guess. We’ll see if I luck out and get an adult (or salvageable DNA) from one of these larvae. Whatever this turns out to be, it looks like I’ll have to add a 138th couplet to my key to North American oak leaf mines.
Also on October 10, I found the 49th distinct type of sawfly larva for this year’s yard list: a dazzling, solitary one on one of our cultivated hazelnuts (Corylus ‘Medium Long’), unlike any I’ve seen before on that plant.
On October 13, it molted to a prepupa and I transferred it to a jar of soil. When I checked yesterday it had burrowed down to overwinter and pupate.
On October 11, I finally collected the mysterious Leafminer #153, which forms a short mine in a leaf blade of garden phlox before disappearing into the midrib and, I surmised, completing its development as a stem borer without leaving any further external evidence.
I split open a couple of stems that had mines like this, and sure enough, something had been tunneling in the pith:
Since the mine isn’t really visible in the leaf midrib and since the midrib and stem are difficult to dissect cleanly, I wasn’t able to see the mine actually transitioning from the leaf to the pith of the stem, but I confirmed that there was no tunneling in the stem immediately above a mined leaf but there was a tunnel right at the node with the mined leaf. I didn’t want to break apart too many stems for fear of damaging the larvae or pupae that I hope are still inside, but it seems that the tunneling continues all the way to the ground. Hopefully I got enough of the root to capture the mystery bug, and will be able to see who comes out in the spring.
This next one isn’t from my yard, but worth mentioning: On October 12 I awoke to discover that a fly had emerged from one of the jars of soil I keep on the dresser next to the bed—the first sign of life there in several months. It turned out to be a Chirosia (Anthomyiidae) from a leaf mine on silvery spleenwort (Deparia acrostichoides) that Julia and I had collected in Vermont while on a field trip with the New England Botanical Club—on June 16, 2019! Usually there’s no point in keeping a jar of soil around for more than a year, and this one had completely dried out, but I’d been reluctant to give up on it because the single larva that had burrowed into it held the answer to a long-standing mystery that I haven’t had many opportunities to pursue.
So what species of Chirosia is it? I dunno, they all look like this. We’ll find out whenever Brad Sinclair gets to go back to work at the Canadian National Collection and I can send it to him.
Between October 10 and 12 (I haven’t been checking the rearing vials everyday lately because things have really slowed down), a braconid emerged from the Phyllonorycter kearfottella mine on Chinese chestnut that I’d collected on September 27 (#195). I think it’s a miracine:
Multiple times over the past few weeks, I’ve checked the black birch saplings in the “lower nut orchard” for leaf mines of Ectoedemia occultella (Nepticulidae). I’ve only found this species three times in the past decade, and never in my yard, but I’ve just felt like it should be here. And at least as often as I’ve been checking those birches, I’ve been checking our driveway (at the opposite end of our yard) to see if a leaf with one of the “green island” Ectoedemia species has blown in from the quaking aspen across the road. Yesterday, as Julia and I returned from a walk up the Crag, we stopped by the mailbox to look for the latter, and Julia spotted a leaf with a hint of a green island on it—but rather than blowing from the aspen across the road, it had fallen from the paper birch (Betulaceae: Betula papyrifera) at the edge of our own yard. The little bit of green on the otherwise yellow leaf marked the edges of an Ectoedemia occultella mine! So that’s Leafminer #205:
As you can see, this species makes a small blotch mine without any initial linear portion, bounded by two adjacent lateral veins, with a characteristic dark circle in the middle, on the underside of which the tiny, shining eggshell can be found.
It’s been a little while since I updated the list of plants I’ve eaten from the yard this year. Julia says I get to count potted plants on our deck and in the house, since the house is in our yard, so:
118. Ginger (Zingiberaceae: Zingiber officinale) – rhizome
119. Fig (Moraceae: Ficus carica) – fruit
120. Asian pear (Rosaceae: Pyrus pyrifolia) – fruit
121. Butternut squash (Cucurbitaceae: Cucurbita moschata) – fruit/seeds
122. Some sort of melon (Cucurbitaceae: Cucumis melo) – fruit