The Yard List(s), Part 26

Before I launch into the latest leafminers from my yard, I have a few sawfly updates. On July 11 I had collected this spotty larva on black raspberry:

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It burrowed into soil to pupate five or six days later. Alas, on September 8, this ichneumon wasp emerged, much like the one that emerged on August 26 from the un-spotty larva on red raspberry.

Since a tachinid fly emerged from a larva I found on blackberry, it’s looking pretty unlikely that I’ll get any adults of these mystery Rubus-feeding sawflies. I guess there’s always next year…

On September 1 I had found these larvae feeding together on a hazelnut leaf, and the larger one matched the ones from which I’ve reared Arge willi (Argidae) in the past, but I wasn’t sure if the smaller ones were the same thing.

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On September 7 they still had red heads…

…and they looked the same on September 11, but on the 12th they had brown heads and resembled the larger larva (which had already spun a cocoon by September 7), so they are in fact all Arge willi:

Sawfly #47: Caliroa sp. (Tenthredinidae), on red oak (Fagaceae: Quercus rubra). On September 5, right next to the leaf mines of Tischeria quercitella, I found a solitary “slug” sawfly larva feeding on the underside of a leaf. I didn’t mention it in my previous post because I wasn’t certain it wasn’t a younger version of the same species I’d found on Chinese chestnut, but now that I’ve finished watching it develop I can confidently add it as another distinct Caliroa for the yard list—after #26 on quaking aspen, #36 on shadbush, #39 on Chinese chestnut (Caliroa ?lobata), and #43 on pear (Caliroa cerasi). When I found the larva it had recently molted, and its head and legs were colorless, but it was evident from its shed skin that the previous instar had had a brown head and legs. (The “floating” fecal pellets in these photos are caught in a spider web that was spun across the underside of the leaf.)

Here’s the same larva the next day, with its head and legs now colored in. I caught it at an awkward moment when its body was twisted, showing a full suite of abdominal prolegs.

This was the final instar, and it had molted to a prepupa when I checked on the morning of September 10:

In contrast with Caliroa lobata, the larva never got more than a slight hint of yellow on the thorax, and the head and thorax never got quite as dark as in that species. Also, C. lobata is consistently gregarious, and this species seems to be solitary. On September 13 on a walk in the woods behind our house, I found recently hatched larvae that I think are C. lobata (again on red oak), and I learned that even at this stage they have a distinctly yellow thorax and dark legs and head. Here’s what their “window feeding” looked like from above; the dots to the right indicate where the eggs were laid:

The same scene from below:

And a closer look:

On to the leafminers (interspersed with some other creatures found in the garden).

Leafminer #181: Liriomyza sp. (Agromyzidae), on amaranth (Amaranthaceae:  Amaranthus hybridus). I found several of these mines in the lower vegetable garden on September 8 while browsing on cherry tomatoes and ground-cherries. I’ve only seen these mines once before—when Julia found some on a farm just over the border in New Hampshire—and I’m reasonably sure they don’t represent any of the Liriomyza species known to feed on amaranth (L. huidobrensis, L. sativae, and L. trifolii, all of which are polyphagous species that I’ve never found in New England). This species likes to switch back and forth between the upper and lower leaf surfaces, as you can see here:

On September 11, Julia was turning the compost in the upper vegetable garden and found a nest… no doubt belonging to the same voles who have been relentlessly cutting down the bean plants all season.

Leafminer #182: Stigmella rhamnicola (Nepticulidae), on common buckthorn (Rhamnaceae: Rhamnus cathartica). I am by no means a native plant purist, but there are certain plants that don’t “play well with others,” and which we try to pull up whenever we find them on our land: common buckthorn, glossy buckthorn, multiflora rose, Oriental bittersweet, Japanese barberry, Morrow’s honeysuckle, and black swallowwort. Several of these plants are utilized by native leafminers—in my last post I showed mines of the beetle Sumitrosis rosea on bittersweet—and common buckthorn is another example. I wrote about its use by Stigmella rhamnicola seven years ago; as I noted then, this native moth is surely much more common in New England now that this European plant is widespread here. On September 12 I spotted a couple of small plants that had sprouted up among the brambles in the “upper nut orchard,” and when I pulled them up I found several old, aborted or predated mines:

I also recently found some mines of the native Stigmella rosaefoliella on some multiflora rose that is just outside what I can reasonably call my yard, so I don’t get to add that species to the list (yet…).

On the morning of the 14th, while washing the kale leaves we had picked for breakfast, Julia found a cabbage white caterpillar with a mass of braconid cocoons. These cocoons (and the caterpillars) are a common sight in the hoop house right now, but this one still had a freshly emerged braconid larva that hadn’t started spinning its cocoon yet:

Later that morning, I decided to check on the small American elm tree at the west edge of the yard to see if any new leafminers had shown up since I last looked. It did not disappoint.

Leafminer #183: Phyllonorycter argentinotella (Gracillariidae).

Leafminer #184: Ectoedemia ulmella (Nepticulidae).

Leafminer #185: Stigmella apicialbella (Nepticulidae).

A search of other plants in the yard turned up one more new species for the year:

Leafminer #186: Ectoedemia quadrinotata (Nepticulidae), on cultivated hazelnut (Betulaceae: Corylus ‘medium long’). It’s theoretically possible that this mine was made by E. virgulae, but I’ve reared E. quadrinotata from the yellow birch in my yard in previous years and have never seen any evidence that E. virgulae is here. This is also identical with the E. quadrinotata mines I’ve seen on hazelnut elsewhere.

Here’s one of the ones I reared from yellow birch, displaying the four spots (per wing) that give it its name:

I’m undecided about whether this little excavation at the tip of a blue spruce needle (from one of the trees at the north edge of the yard) deserves to be called a mine. If I get to the end of the year and find that my yard leafminer tally is at 199, I might have to call upon it to get to an even 200, but we’ll ignore it for now…

About Charley Eiseman

I am a freelance naturalist, endlessly fascinated by the interconnections of all the living and nonliving things around me. I am the lead author of Tracks & Sign of Insects and Other Invertebrates (Stackpole Books, 2010), and continue to collect photographs and information on this subject. These days I am especially drawn to galls, leaf mines, and other plant-insect interactions.
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