Dill Moths (and others)

On Tuesday I noticed webbing at the tops of some dill plants in the garden, with moth pupae suspended within.  Most webs had a single pupa, but this one had three:

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Investigating further, I saw that the developing seeds on these plants were being devoured:

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…and I saw this moth resting on one of the webbed umbels:

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It seemed likely that this moth was the adult form of the caterpillars that were eating the seeds and pupating in the webbing, but just to be sure, I collected a few pupae.  The next day, several of the same moths emerged.

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To figure out what kind of moths these were, I started by searching the HOSTS database, and found that the only dill-feeding Lepidoptera listed are some swallowtails (Papilio; there was in fact a plump black swallowtail caterpillar clinging to the stem of one of the dill plants in question), two inchworms (Geometridae), an owlet moth (Noctuidae), and a tortricid.  I knew these moths belonged to none of those groups; their distinctively sharp, upturned mouthparts told me they belonged to the superfamily Gelechioidea.

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By chance, yesterday I happened to see a photo of an adult parsnip webworm (Elachistidae: Depressaria pastinacella), and I realized this must be something close to that.  So I browsed BugGuide and quickly found the purple carrot-seed moth (D. depressana), which was recently introduced to northeastern North America from Eurasia. Based on the map at Moth Photographers Group, the records so far are mostly from southern Ontario, with a couple in adjacent southern Quebec and one near Rochester, New York.  So my moths in western Massachusetts apparently represent a substantial, though unsurprising, range expansion for this species.  The known host plants of this moth are all in the parsley family (Apiaceae): Daucus (carrot), Pastinaca (parsnip), PeucedanumPimpinella (anise), and Seseli.  So dill (Anethum) evidently is a new, but similarly unsurprising, host plant.

I think it might be poor form to devote my only post during National Moth Week to an introduced pest species, so I’ll end by taking stock of the other moths I’ve met this week.

On Sunday, I saw my first Clymene moth (Erebidae: Haploa clymene) on a walk in the woods behind my house.

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Otherwise, I’ve been busy writing reports all week, and the other moths I photographed all came from leaf mines I collected earlier this summer:

A 3-mm Elachista (Elachistidae, the same family as the dill moths) from quackgrass (Elymus repens)…

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A 2.3-mm Stigmella (Nepticulidae) from red oak (Quercus rubra)…

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Most photos I took, like the one above, only hint at the brilliant iridescence of this moth. This top view did a better job:

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A very differently patterened, 1.7-mm Stigmella from chestnut oak (Quercus prinus)…

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A 3-mm Phyllonorycter (Gracillariidae) from sugar maple (Acer saccharum)…

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A 3.7-mm Mompha (Momphidae) from meadow evening primrose (Oenothera pilosella)…

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A 2.3-mm Phyllonorycter from American chestnut (Castanea dentata)…

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A 3.9-mm Cameraria (Gracillariidae) from pin oak (Quercus palustris)…

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(That one, incidentally, refused to hold still, and required maybe half an hour in the freezer to prevent it from flying as soon as I dumped it out of its vial.  Even so, all I was able to get were awkward action shots like the one above as it ran about in a frenzy.)

…And finally, a 4.5-mm Parornix (Gracillariidae) from gray birch (Betula populifolia).

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And those, of course, are just the week’s moths.  No wonder it took me all week to get those reports finished.

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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3 Responses to Dill Moths (and others)

  1. MARY Beth martin says:

    Love you’re blog, do you have any idea what this is ? I found it on blackberry, in central Maine on July 26, thanks

  2. Great set of shots, Charley. Best regards, Mike.

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