Introducing Grapholita thermopsidis

Almost every year since we bought our house, Julia and I have spent a few weeks on a road trip in search of exciting new leafminers. At this point we’ve visited nearly every US state and two Canadian provinces. This year, we’re looking forward to sticking around the homestead for the entire growing season for a change, but our past collecting trips continue to bear fruit. Today, for instance, a moth species we discovered in Colorado five years ago finally has a name.

In July 2015, our travels were centered around a visit to our friends in Colorado, Sally Waterhouse and Denny Radabaugh, who were Julia’s biology professors in college and who officiated at our wedding. This was the trip on which we found the rose leaf-mining sawfly Fenusa julia. Exactly one week earlier, we were poking around Sally and Denny’s yard and checking out the unusual (to us) plants in it when we spotted some mines on Thermopsis (Fabaceae), a plant known as goldenbanner or false lupine.

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From above, the mines were visible as only slight discoloration, and they were only conspicuous because of the way they caused the leaflets to buckle.

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The mines were perfectly distinct when viewed from below.

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“Underside tentiform mines” like these are characteristic of certain moths in the family Gracillariidae, and on a legume like Thermopsis the expected genus would be Macrosaccus. However, upon collecting some of these mines, it soon became apparent that the larvae inside were expelling their frass:

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A few gracillariids expel frass from their mines, but none of these are species that make tentiform mines, so this was something weird. At this point my leafminer book manuscript was far enough along that I knew the only documented leafminer on Thermopsis was Parectopa thermopsella (Gracillariidae), described in 1875 by V. T. Chambers, who collected the species in Colorado. No specimens of Parectopa thermopsella are known, but there is nothing in Chambers’ description of the leaf mine or the adult that indicates how it would be distinguished from the moth now known as Micrurapteryx occulta, which Annette Braun described in 1922 as Parectopa occulta and mines leaves of a variety of legumes. We found mines of “Parectopa thermopsella” during that trip to Colorado. They are flat, upper-surface mines, with a more or less lobed or “digitate” shape. Each lobe represents a different feeding excursion; in between bouts of feeding, the larva returns to a point along the midrib where it expels its frass through a hole in the lower epidermis.

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In the lower-surface view above, you can see the initial linear track the larva makes on the lower leaf surface before switching to the upper surface to make a blotch mine. Unfortunately we were unable to rear any adults of “Parectopa thermopsella,” but they would look something like this Micrurapteryx we reared from a similar mine on Astragalus during the same trip to Colorado:

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Anyway, ten days after we collected the mystery mines on Thermopsis, some larvae had abandoned their mines and were continuing to feed on the leaves externally, within shelters made by rolling or tying the leaves with silk.

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A few days after that, parasitoid wasps started emerging from some of the mines. These little ~1 mm beauties are a female and male Zagrammosoma mirum (Eulophidae):

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There were also a few braconid wasps, a little shy of 3 mm long:

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So far, what José Fernández-Triana has been able to tell me about them is that they are in the genus Dolichogenidea. Their DNA barcode matches that of some specimens from Canada, but the species has not yet been identified (if it in fact has a name).

Fortunately, some of the moth larvae escaped parasitism and pupated in early August.

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It was clear by now that this moth was not a gracillariid at all, but I wasn’t quite sure what it was. It wasn’t until the following spring that the adults finally emerged:

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I knew they belonged to the family Tortricidae, which are commonly known as the “leafroller moths.” I sent them to Jason Dombroskie at Cornell University, who confirmed his impression from my photos that they belonged to the genus Grapholita.  He suspected they represented an undescribed species, but he didn’t have time to investigate further.

Last year, when I heard that moth aficionado Kyhl Austin had become Jason’s grad student and was focusing on Tortricidae, I seized the opportunity to ask Kyhl if he could take a look at these specimens. He was happy to, and within a few weeks he had confirmed that they belonged to a new species and described them in intricate detail. He also dissected and identified all of the other tortricids I’d sent to Cornell, several of which had not been reared before or were not known to start out life as leafminers. Today our paper* was published, in which the new species is named Grapholita thermopsidis and the natural history of six other leaf-mining tortricids is discussed.

At ~5 mm long (wingspan ~1 cm), this is the largest insect species I’ve had the pleasure of naming. It is the third moth species I’ve coauthored, and it occurs to me that each moth has taken five years after its initial discovery to actually get described (although with Marmara viburnella  what took so long was successfully rearing adults, and the species description was published the following year). Many more new moths await, so hopefully I can pick up the pace a bit!

* Eiseman, Charles S., Kyhl A. Austin, Julia A. Blyth, and Tracy S. Feldman. 2020. New records of leaf-mining Tortricidae (Lepidoptera) in North America, with the description of a new species of Grapholita. Zootaxa 4748(3): 514–530.

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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6 Responses to Introducing Grapholita thermopsidis

  1. David Gregg says:

    Great story. Thanks.

  2. bradley102015 says:

    Fabulous post, great information and beautiful photos! I look forward to reports from the time you spend exploring your property. I’m constantly amazed by the variety we have found in our small (1.3 acre) yard among the cornfields here in Ohio. I’ve documented 191 species of spiders in our yard so far. Obviously not all are permanent residents, certain species blink in-and-out of presence, but the list keeps growing. I was once told by a dear friend (birder) who I paraphrase as “wait long enough and pay attention and they will all show up eventually.” She was referring to vagrant birds appearing in her neighborhood, but spiders (most of them) fly too, and sooner or later may show up.

    • I’ve been sporadically adding to our “yard list” since we moved here and the invertebrate list currently stands at 736 species. Probably the moths alone should number that many, but I’ve never done any blacklighting or really any focused inventorying, just jotting things down as I happen to notice them (or ID things I’ve photographed or collected to rear). It will be interesting to see how much the list grows when I’m spending more time at home. So far just 31 spider species, of which my favorite is the Uloborus glomosus that lived in our stairway for a few months last year.

  3. Judy says:

    Fascinating. I wonder if there are folks out there who would be interested in knowing what’s in their own back yards. Bet there are–what an eye opening education you could give them!

    • David Gregg says:

      One similar example I know of is the work being done by Aaron Hunt, who’s documenting inverts on Block Island, Rhode Island. Check out his thousands of posts on bugguide under the handle “Blocky”. Great effort.

  4. Jennifer Kleinrichert says:

    Congratulations! How exciting to meet new invertebrates. 😃 I found a tiny cocoon attached to a piece of wood in our woodpile yesterday and hope to see who emerges. We have quite a collection of firewood on the porch that is nonburnable till the critters emerge. Glad you two get some more homestead time this summer! We are 100% smitten with A. persimmon and plan to add many more. I’m sure you’ve seen it, but just in case…the Native Plant Agriculture book by Indigenous Landscapes in Cincinnati is fascinating. Thanks for your patience with these leaf miners. It’s very important work to know who we share this planet with!

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