If you’ve been following along throughout my cataloging of the leafminers and sawfly larvae I’m finding in my yard this year, you may remember that in the first half of July I found several free-living sawfly larvae—representing at least two different species—on raspberry and blackberry. I have no idea what they are beyond family Tenthredinidae, so I collected each one hoping that I can rear some to adults. One was this plain-headed larva I found on blackberry on July 11 (which seemed to be the same as #32 on red raspberry):
It burrowed into soil to pupate on July 15, and I didn’t expect an adult to emerge until next spring, but on August 26 I noticed something moving in the jar. Alas, it was an ichneumon wasp which had been living as a larva inside the sawfly larva:
This prompted a thorough checking of all my jars of soil, which turned up a fourth adult from my jar of five aspen-feeding Caliroa sawfly larvae, and, darn it, a long-dead tachinid fly from the #32 red raspberry sawfly larva, which I had collected on July 8, and which had burrowed into soil on July 11.
We’ll see how the few other Rubus sawfly larvae fare, although I think they may have all been of the other type, with a dark marking on the head. In the meantime, a number of other species have appeared in my yard in the past week.
Sawfly #39: Caliroa ?lobata (Tenthredinidae), on Chinese chestnut (Fagaceae: Castanea mollissima). On August 29, I noticed some patches that reminded me of the “window feeding” caused by gregarious Caliroa larvae on the undersides of oak leaves.
I’d never seen this on chestnut before, but I flipped the leaves over and found two larvae still grazing away on the smallest spot (there were several much larger patches but the larvae that made them had already dropped to the ground to pupate).
Not all Caliroa larvae have been described, but among those that have, the yellow-sided thorax and dark head and legs make these a perfect match for C. lobata, as documented in a paper I recently published with Dave Smith*. So far that species has only been reared from oaks, but all sorts of oak-feeding insects have turned up on our Chinese chestnuts, so it won’t be surprising if these turn out to be the same thing.
One of them molted to a prepupa on September 2:
The other did the next day, and both burrowed into soil as soon as it was offered. But back to August 29…
Leafminer #161: One of two maple-feeding Cameraria spp. (Gracillariidae), on red maple (Sapindaceae: Acer rubrum). A couple of tiny mines just getting started on this leaf:
As far as I know, Cameraria aceriella and C. saccharella can’t be distinguished at this stage, although I wonder if both species have such dark larvae. I’ll keep an eye on them… The mine on the right is just 8 mm across, but in a backlit closeup, we can see that the larva has already molted once. (The head capsule is near the bottom of the photo, and the rest of the shed skin is right by the tip of the larva’s abdomen.)
Right near the chestnut and maple, I noticed this long, narrow, linear mine formed entirely on the lower surface of a grass-leaved goldenrod leaf (Asteraceae: Euthamia graminifolia).
Ophiomyia euthamiae (Agromyzidae) was described from a series of flies I reared from similar mines found within 100 feet of this one, but each of those mines switched to the upper surface, where the puparium was formed. The single mine like this—with everything including the puparium being on the lower surface—produced an adult of O. maura, which is a species I’ve already included on this year’s yard list based on upper-surface mines on Solidago goldenrods. (Yes, oddly, on every other known host, O. maura forms exclusively upper-surface mines.) So I’ll have to find an unambiguous mine of O. euthamiae before I can add that species to the list.
Leafminer #162: Mompha argentimaculella (Momphidae), on evening primrose (Onagraceae: Oenothera biennis).
I’ve been watching for this one all summer on the abundant evening primrose around the yard, and finally spotted this one mine out of the corner of my eye when I went down to check on the tiny baby chicks, who had wandered through the fence that surrounds the chicken run but weren’t getting into too much trouble.
Leafminer #163: Phytomyza lactuca (Agromyzidae), on tall blue lettuce (Asteraceae: Lactuca biennis), on the other side of the chicken run. I had never before seen a mine of this species, which mines exclusively on the undersides of leaves, and I only noticed this one because this particular leaf had flopped over.
I found several other P. lactuca mines on the same plant, but in each case the puparium had an exit hole of a parasitoid wasp. I thought it would be nice to rear an adult of this species, so I visited a bunch of other tall blue lettuce plants around the yard, flipping leaves over, without finding anything. Until, that is, I got to the exceptionally tall plant by the vegetable garden that I showed at the end of my previous post. I found a mine there that still had a larva inside, but when I took a picture of it, the mine seemed to have a continuous central frass line, indicating a moth rather than a fly:
I thought I was seeing things, but a photo with my better camera setup showed this more clearly:
Leafminer #164: Marmara sp. (Gracillariidae), on tall blue lettuce. The only previous indication that there is a lettuce-feeding Marmara is a series of observations Mike Palmer made in Oklahoma, involving empty or aborted mines that were either formed entirely in the stem or began on the upper leaf surface and led into the stem (or crown, in the case of basal rosettes). Could this be the same species? I have no idea; either way, it doesn’t have a name. I didn’t try for a super close-up for fear of squishing the larva, but this backlit shot shows enough detail to confirm it’s a Marmara:
I found a few other Marmara mines on this same plant, all of them visible only on the lower surface. I’m going to wait until the larvae are nearly mature before collecting the leaves, since lettuce leaves don’t last long once picked. A week later, they haven’t made much progress; Marmara larvae are not the speediest of leafminers.
Leafminer #165 / Sawfly #40: Metallus rohweri (Tenthredinidae), on blackberry (Rosaceae: Rubus allegheniensis). The raspberry leaf-mining sawfly, M. capitalis, appeared in my yard back on June 18 and its second round of larvae showed up a little while ago, but M. rohweri, which has just one generation per year in Massachusetts, waited until August 30 to make its appearance.
Leafminer #166: Aspilanta ampelopsifoliella (Heliozelidae), on a Virginia creeper vine (Vitaceae: Parthenocissus quinquefolia) growing up the trunk of the silver maple. An aborted mine, but recognizable by its prolonged initial linear portion. This species was, until a few weeks ago, known as Antispila ampelopsifoliella**.
Leafminer #167: Glaucolepis saccharella (Nepticulidae), on red maple.
This is Brenda, who accompanied me on my leafminer hunt that day.
Leafminer #168: An unknown insect on Siberian iris (Iridaceae: Iris sibirica).
I found this single mine on a leaf right along the driveway. It doesn’t look like Cerodontha (Agromyzidae), and the only other known iris leafminers is Macronoctua onusta (Noctuidae), which makes narrow leaf mines in the spring, later feeding within leaf sheaths and boring in flower buds, stalks, and eventually the rhizome. If this is a mine of that moth, that would mean it’s been there all year and I somehow didn’t notice it until now. I’ll have to look for feeding signs of older caterpillars.
Sawfly #41, on the same pussy willow (Salicaceae: Salix discolor) that has already hosted two generations of another sawfly species this year (#9). On the morning of August 31, before heading out for our last day of dragonfly surveys, I dashed out to collect some willow leaves to feed some other sawfly larvae I had found at work a few days earlier, and I discovered that these larvae had just hatched from a cluster of eggs on the underside of one of the leaves:
Whereas the previous willow sawfly larvae had grazed on one leaf surface throughout their development, these had begun eating holes in the leaf immediately after hatching. On September 2 when I went out to collect some more leaves for the ravenous larger larvae, the leaves more often than not had clusters of still unhatched eggs on the undersides (which doesn’t bode well for the longevity of those leaves):
Most clusters looked like the one above—translucent shells with black-headed embryos visible inside—but in one, the eggs had cloudier shells and a pair of red eyespots at one end.
The latter turn out to represent the former at a later stage; this morning I found that all the eggs in the second photo had hatched, and the ones in the first photo are now cloudy with the red eyespots.
Leafminer #169: Cameraria betulivora (Gracillariidae), on yellow birch (Betulaceae: Betula alleghaniensis). Since it’s getting to be the time of year for all sorts of Cameraria to show up, on September 1 it occurred to me to check the yellow birch at the edge of the woods where I’d found this species a few years ago. I parted the grapevines that have engulfed the tree, and there the mines were:
Leafminer #170: Chirosia gleniensis (Anthomyiidae), on sensitive fern (Onocleaceae: Onoclea sensibilis). And right next to the yellow birch was a single old mine made by three larvae of this fly, in the very patch of ferns I had checked multiple times this year without success.
If you look closely, at the left side of the photo below you can see the cluster of three whitish eggs from which the larvae hatched.
Leafminer #171: Antispila cornifoliella (Heliozelidae), on gray dogwood (Cornaceae: Cornus racemosa). Similarly to the pair of Metallus sawflies on Rubus species, there are two Antispila species on dogwoods in my yard, one of which (A. freemani) appeared early in the season and is now in its second generation, and the other is just now making its first appearance.
In a backlit view, we can see that the larva started by making a narrow linear mine along a lateral vein and the midrib, causing the reddish discoloration seen above.
Sawfly #42: Arge willi (Argidae), on hazelnut (Betulaceae: Corylus ‘Medium Long’). Every year this species appears on our cultivated hazelnut in large numbers, and I’ve been wondering why they aren’t showing up this year. Finally on September 1 I found a single larva matching the ones I’ve reared before, hanging out with several young ones with reddish heads. Whether these turn out to be the same species remains to be seen.
Also on that hazelnut was one of those green lacewing larvae that run around with fluff piled on their backs. It was in constant motion, making it incredibly difficult to get a shot that was at all in focus.
Sawfly #43: Caliroa cerasi (Tenthredinidae), the pear slug, on our newest pear tree. It baffles me that this is considered to be a pest worth worrying about; I never find larvae in large numbers, and they just do a little “window feeding” nibbling here and there (whereas some of the other sawfly species in my yard do defoliate entire branches). I think I had noticed some nibbles a little earlier in the season, but on the evening of September 1 I made a more concerted effort to find the larva responsible for them. Here is some lower-surface window feeding, as seen from above and below:
Unlike most Caliroa species, which feed strictly on the lower surface, the pear slug may feed on either surface, and it was next to an upper surface feeding patch that I found a shed skin confirming that it was actually a Caliroa larva doing the feeding.
Julia walked over and joined the search, and she was the first to spot the actual larva:
To the uninitiated it would appear to be just a wet lump of poop, but here’s its face peeking out from under its shroud of slime:
And on that note, I’ll sign off for the weekend!
* 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.
** Nieukerken, Erik J. van and Charles S. Eiseman. 2020. Splitting the leafmining shield-bearer moth genus Antispila Hübner (Lepidoptera, Heliozelidae): North American species with reduced venation placed in Aspilanta new genus, with a review of heliozelid morphology. ZooKeys 957: 105–161.