I’m not sure if I ever mentioned it explicitly, but the reason I spent two and a half months last fall exploring the western US, and another month this spring exploring the southeast, is that I’m working on a new book about North American leaf-mining insects. For more about this project, you can have a look at this page (the “Leafminers” tab in the menu above). In the course of my travels, I got photos of many of the mines I was looking for, and I also accumulated hundreds of photos of mines in host plants I haven’t identified yet. Identifying all of these on my own would be extremely time-consuming, especially given that most of the plants were not in bloom when I saw them, and my hope is that I have some readers in other parts of the continent who know their local plants as well as I know the ones in the Northeast.
To that end, I’ve been uploading my photos of mystery plants to my Flickr page, organized by state. Usually I know the family if not the genus, and in some cases I have a guess for the species but am looking for confirmation. In moving counterclockwise around the country, I’ve just made it to northern California in my photo sorting, so over the next few months I’ll be adding more photos from California, Arizona, Texas, and the Southeast. I’ve inserted a feature in this blog’s sidebar with thumbnail links to the ten most recently uploaded photos, and if you hover your mouse pointer over one you can see my approximate ID.
Once I know what these plants are, I can figure out whether the mines match anything that has been described before. The photos below, from Solano County, California, show something that I suspect has not. The plant is something in the aster family, but that’s all I know; anyone recognize it? (You can click on the photos to enlarge them.)
The leaf mines were partially transparent and contained no excrement (“frass”), as the fastidious larvae had pushed it all out of the leaves.
In one leaf, the larva had finished feeding and had spun a roundish cocoon inside.
The combination of the mine characteristics and the fact that the plant was in the aster family suggested that the miner was a moth in the genus Astrotischeria (Tischeriidae). Sure enough, about three months after I collected a few of these leaves, I found this moth in the vial:
This moth does have the general appearance of an Astrotischeria, but I don’t think it is any of the named Astrotischeria species that are known to occur in California. Interestingly, the California Moth Specimens Database lists a specimen labeled as “Tischeria ns grayish brown” collected at the exact location where this moth originated: UC Davis’ Stebbins Cold Canyon Reserve. The genus Tischeria has been split into a few new genera recently, one of which is Astrotischeria. The “ns” stands for “new species.” That specimen was collected in 2009 by John DeBenedictis, who has been collecting micro-moths at Cold Canyon for many years. As it happens, on my way out of town I stopped at UC Davis and photographed a bunch of his specimens, but I’m not sure if that one was among them (haven’t gotten there yet in my sorting).
I don’t know if anybody is in the business of describing new tischeriid species these days, but if I can put a name on the host plant, that will probably improve the chances of someone deciding to take the time to describe and name this moth.
Added 9/16/2013: Thanks to Marek Borowiec for identifying the plant as Brickellia californica! I have found no records in the literature of any insect mining this plant, although an unrelated leaf-mining moth has been reared from B. grandiflora in Colorado.