Bunchberry Squiggler Unmasked!

You may recall that back in September, I wrote about some mysterious squiggles radiating from the bases of bunchberry leaves:

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I rambled on about how I thought they must be caused by a species of Antispila (Heliozelidae), but not A. freemani, the species that is known to mine bunchberry leaves. I ended with these two photos taken the day after I collected the leaves, backlit to reveal the tiny larvae inside:

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Well, three days later the larvae had definitely switched from making linear mines to blotches…

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…and after another three days, the initial linear portions were becoming dwarfed by the blotches:

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If I’d had any lingering doubts about these being Antispila larvae, they were dispelled within two weeks, as all the larvae finished mining and cut out their characteristic oval pupal cases.

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Each case had a distinct longitudinal ridge and several “spokes” projecting from the ends:

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Into the fridge they all went in December, and out they all came in March. Today, the first moth emerged, leaving its pupal skin protruding from the leaf cut-out:

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It’s pretty similar to the moths I’ve reared from the “normal” bunchberry mines, but substantially smaller (~2.3 mm from head to wingtip, versus 3.2-3.5 mm for the others). I’ll have to get somebody to look at the genitalia in order to reach a definite conclusion, but I think it’s clear that there are two Antispila species mining bunchberry.

In reviewing Lafontaine’s (1973) revision of the dogwood-feeding Antispila species*, I see that A. cornifoliella is much smaller than A. freemani, and I suspect that rather than having found a new species, I have found that the hosts of these two moths do not break down as nicely as Lafontaine claimed. He stated that the food plants of A. freemani are “northern species of the genus Cornus typical of damp situations”–bunchberry (C. canadensis), silky dogwood (C. amomum/obliqua), and red osier dogwood (C. stolonifera)–whereas A. cornifoliella feeds on “southern, upland species of Cornus,” e.g. flowering dogwood (C. florida) and alternate dogwood (C. alternifolia). Neither he nor any other author that I know of has described the mines of either species beyond saying that they are blotches.

I have now seen these initially linear mines on bunchberry, silky dogwood, and alternate dogwood, and I have seen the simple blotch mines on bunchberry, alternate dogwood, and roughleaf dogwood (C. drummondii).  To confuse things just a little bit more, on stiff dogwood (C. foemina) in Florida I found some mines that were sort of intermediate, beginning with a broader linear mine:

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Well, it’ll all get sorted out eventually, I guess.  Or not.

* Lafontaine, J. D. 1973. Eastern North American species of Antispila (Lepidoptera: Heliozelidae) feeding on Nyssa and Cornus. The Canadian Entomologist 105(7): 991-996.

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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4 Responses to Bunchberry Squiggler Unmasked!

  1. Can I expect to find these guys mining red osier dogwood in Wyoming?

    • Good question. Currently, Antispila cornifoliella is only known from Ontario and Quebec south to the Gulf Coast, so if I’m right about that being the species that makes the squiggly lines, you shouldn’t find it there. When Lafontaine described A. freemani, it was known from Nova Scotia to Ontario, but based on the map here it can be found across Canada and south through New England. There is one other Antispila on dogwood: Annette Braun described A. aurirubra from California, and later found it in northern Utah. It does feed on red osier dogwood. So if you find mines in Wyoming, they would most likely be that species. Braun was usually pretty detailed in her descriptions of mines, and she just said that species makes brownish blotch mines, so they probably look something like these that I found in Iowa (which, based on my new thinking, appear to be the southernmost A. freemani ever found, and not A. cornifoliella as I originally assumed).

  2. Pingback: Dogwood Hole Punchers | BugTracks

  3. Alan @ it's not work, it's gardening! says:

    Fascinating stuff as always Charley! As a gardener I once thought that “leaf miner” was a pretty precise description, but you’ve helped educate me.

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