Before I launch into listing the latest leafminers to appear in my yard, I have a request related to these mines I found on a grape leaf back on June 10:
Linear mines on grape leaves are made by larvae of moths in the genus Phyllocnistis. The short version is, I’m hoping folks in the western US will keep an eye out for these and send me some. If you find any, please email me (firstname.lastname@example.org).
The longer version is, when I was working with Don Davis on the Gracillariidae section of the Annotated taxonomic checklist of the Lepidoptera of North America, North of Mexico that will be published later this year, I learned that Don was planning on synonymizing Phyllocnistis vitifoliella with P. vitegenella because the adults of these two grape-feeding species don’t seem to be distinguishable. However, I am convinced not only that they are two distinct species, but also that there is a third, undescribed species in the western US. I won’t go into all the evidence right now, but the hypothesized species are easy to distinguish by their leaf mines. Phyllocnistis vitifoliella makes distinct mines that are nearly filled with frass, as in the photo above. I believe it only occurs in eastern North America (and has been introduced in Europe, where it is being referred to as P. vitegenella).
Phyllocnistis vitegenella makes an indistinct, entirely epidermal mine resembling a snail trail, with no visible frass. It occurs throughout North America.
The alleged third species forms a distinct mine with a narrow, central frass line. Mines have been found in California, Arizona, Utah, and Colorado, but no adults have been reared from them as far as I know. Both this species and P. vitifoliella are occasionally found on Virginia creeper (Parthenocissus).
So I’m hoping for western material of grape and Virginia creeper Phyllocnistis mines, especially those of the third type (but others could be useful too, and I’d be interested to know if anyone finds mines of the first type in the West). I have an opportunity to do some DNA analysis on these, and I don’t necessarily need reared adults for that (although those would be a nice bonus). Larvae or pupae would do just fine, even dead, dry ones.
The leaf in my first photo shows three mines, and I preserved one of the larvae for DNA analysis. It will be interesting to see whether the DNA obtained from that larva belongs to Phyllocnistis or something else, because I suspect all three of the larvae were being slowly devoured from within. When I collected the leaf on June 11, none of the larvae had moved since the previous day. This is the one I preserved:
The remaining two larvae still hadn’t mined any further as of yesterday, and I finally got around to taking a closer look. This backlit view of the end of a mine shows a parasitoid larva (left of center) and hardly any trace of the Phyllocnistis larva.
The Phyllocnistis larva has likewise been obliterated in the end of the other mine, and in this case the parasitoid larva has pupated.
The dots along either side of the pupa are meconial pillars. Eulophid wasp larvae save up all of their poop until they’re ready to pupate. Some then deposit it all in a single pile, as with the Eulophus pupae shown in this post. Some of the ones that specialize in parasitizing leafminers, however, cleverly arrange it in little pillars attached to the floor and ceiling of the mine, which protects them from possible collapsing of the mine as the affected portion of the leaf dries and crumples.
With that out of the way, it’s time to see where my leafminer tally for the yard stands as spring comes to a close.
Leafminer #74: Liriomyza ptarmicae (Agromyzidae). I found this mine on Wednesday (June 17) right next to the Ophiomyia maura mine on goldenrod, but for whatever reason I forgot to include it in my previous post. It was on mugwort/wormwood (Asteraceae: Artemisia ?vulgaris).
This is the fly shown on the cover of Leafminers of North America—a female ovipositing in Artemisia ludoviciana ‘Silver King’ in my mother’s garden:
After spending a considerable amount of time scouring the yard for new leaf mines on Wednesday, I don’t know what to make of the fact that I found four more yesterday evening in the space of five minutes, on my way to pick some lettuce for dinner.
Leafminer #75: Agromyza parca (Agromyzidae). There were a few young mines of this species on deertongue grass (Poaceae: Dichanthelium clandestinum) in the front yard. Agromyza mines on grasses often begin with a cluster of punctures made by the female’s ovipositor. Eggs are laid in some of these, but most are made for “host-feeding” (when the female drinks the fluid that bubbles out of the puncture in the leaf).
Although four species of Agromyza are now known to feed on Dichanthelium spp., A. parca is the one I’ve reared in my yard.
Leafminer #76: Ophiomyia parda (Agromyzidae), on heart-leaved aster (Asteraceae: Symphyotrichum cordifolium).
This is another species whose type specimen came from my front yard. Its name (from the Latin name for leopard) refers to the distinctive widely spaced spots of frass along the length of the mine.
Leafminer #77: Amauromyza flavifrons (Agromyzidae), on mouse-ear chickweed (Caryophyllaceae: Cerastium fontanum).
This fly uses a number of different hosts in the pink family. It is known to feed on mouse-ear chickweed in Europe, but I think this is the first record of it on Cerastium in North America.
Leafminer #78: Liriomyza taraxaci (Agromyzidae). This one was on the lettuce itself!
I don’t remember ever seeing a leaf mine on cultivated lettuce (Lactuca sativa) before. In the past I’ve reared Liriomyza taraxaci from leaves of dandelion (Taraxacum officinale) and tall blue lettuce (Lactuca biennis) in my yard. Or at least what we’re calling L. taraxaci for now; Owen Lonsdale says this is a species complex that he hasn’t been able to sort out yet. The mines on dandelion and tall blue lettuce are pretty different; not surprisingly, this one on cultivated lettuce is similar to the ones on tall blue lettuce.
Leafminer #79: Cerodontha incisa (Agromyzidae). I spotted this one this morning on timothy grass (Poaceae: Phleum pratense) while mowing the narrow strip of lawn between our house and the untamed meadow / orchard / vegetable garden that is our front yard.
This species has a fancy metallic puparium, which is formed inside the mine. There are often several larvae feeding together.
Leafminer #80: Plutella xylostella (Plutellidae). This diamondback moth cocoon was on the underside of a kale leaf that was picked for today’s lunch:
As illustrated in this post from three years ago, larvae of the diamondback moth are briefly leafminers before switching to feeding externally. As also shown in that post, the above cocoon has a cocoon of an ichneumon wasp inside it.
I think of spring as not a very productive time for leafminers, so I’m pleasantly surprised to have found 80 species in my yard this season. How many more will summer bring?
One more update on a previous post: back on May 29, I showed a stem mine of Marmara elotella (Gracillariidae) on our “Dave’s Delight” apple tree. Today the adult emerged, and since my usual white background wouldn’t do for a predominantly white moth, it was kind enough to pose on an apple leaf. It sat perfectly still for many minutes, except for its antennae, which were twirling constantly.
This may be the first time this species has been photographed alive, unless there are some photos out there that have been determined only to genus. Given that there are dozens of undescribed Marmara species, it’s not a good idea to try to put names on adults found at lights or otherwise not associated with a host plant.
And before I sign off, let’s see where the list of plants I’ve eaten from my yard stands at the end of spring:
62. Sugar snap peas (Fabaceae: Pisum sativum) – fruits
63. Amaranth (Amaranthaceae: Amaranthus sp.) – leaves
64. Mallow (Malvaceae: Malva sp.) – leaves
65. Yellow salsify (Asteraceae: Tragopogon dubius) – leaves
66. Nasturtium (Tropaeolaceae: Tropaeolum majus) – leaves
67. Chard (Amaranthaceae: Beta vulgaris) – leaves
We’ve had very little rain over the past few weeks, and I’m constantly amazed that all these plants that are feeding me and Julia, the bugs, the rabbits and voles and chipmunks, and everyone else in my yard are made of nothing but sunlight, air, the powdery, bone-dry soil, and whatever water they can glean from it.