Flightless, Female, Invasive Linden Looper Moth

Subject: White and black insect in MN
Location: SE Minnesota
October 24, 2014 8:43 am
This insect was seen on October 22, 2014, in southeast Minnesota (Minneapolis). It was about 5/8 to 3/4 of an inch in length. It was on an aluminum storm door’s frame (the green background), at about 5:30 p.m. (less than an hour before sunset). It stayed in the same place (did not climb the door frame, etc.) at least through the time we went in at sunset to fix supper. It was no longer there the next morning (no surprise). Temperatures were probably in upper 50s Fahrenheit. The porch is raised about four feet above ground level. There is a dogwood tree next to it, with branches touching the porch roof and supports. The ground below the dogwood is occupied by hostas. The body texture appeared a bit like moth wings, i.e., as though there were small scales, but in the photo the body looks smoother. The body is more flat than round, in case the photo does not show that sufficiently.
Signature: Curious in MN

Someone else has told me the insect is probably a wingless female linden looper moth, Erannis tiliaria.  Photos of the wingless female linden looper elsewhere (e.g., at the end of the page at http://www.wci.colostate.edu/shtml/LindenLooper.shtml and at http://www.invasive.org/browse/TaxThumb.cfm?fam=210&genus=Erannis) appear to be the same general size, color, and pattern, and there are indeed linden trees in the boulevard strip about thirty feet from the porch, up and down the street. Not that I’ve seen info yet to say that the linden looper feeds on or uses for egg-laying only linden or basswood trees, despite the “tiliaria” name; it might be tolerant of other species, too, even dogwoods.  Also, the mating season is said to be in the fall, and I probably should not have omitted from my original post that the porch is roofed, with a low-wattage light that attracts moths, including presumably any male Erannis tiliaria in the vicinity.  So you can probably mark this one as closed.

Female LInden Looper Moth
Female LInden Looper Moth

Dear Curious in MN,
While this file is closed for you and may not require any additional information on our part, we are still thrilled that you followed up with the identification of the wingless, female Linden Looper Moth and that you provided so many helpful links so that we can prepare a posting for our readership.  The introduction of invasive, exotic species continues to be a significant threat to agriculture and native species diversity.
  We did locate a related species in our archives, a female Mottled Umber Moth, Erannis defoliaria, which is in the same genus and which is native to Europe.  It is possible that that particular posting from our archives is of the Linden Looper Moth as well.  In doing our research, we discovered your image already posted to BugGuide.

Oops.  I may have jumped too early to a conclusion.  A search for Erannis on your site found a page for a tentative identification of a wingless female of a mottled umber moth on November 29, 2009 in California, that looks very similar, too.  And from the photos of Erannis defoliaria and Erannis tiliaria found elsewhere, I’m not sure I could tell them apart just from a photo of the back. Perhaps you will be sensitive to details in the photographs that might distinguish the two.

We don’t think that we are able to distinguish between the two species, but at least we can be certain that we are dealing with a member of the genus Erannis and that it is an invasive species in North America.  Since you have nearby Linden trees, we would favor your original identification of a Linden Looper Moth.

You’re right, I did ask two places, at your wonderful site and at BugGuide.  I hope that’s not a problem.  If you’re preparing a post, you might be amused to add a link to a picture of E. defoliaria from a British guide (John Curtis’s British Entomology Volume 6, says the Wikipedia attribution of the image) over a hundred years ago: http://upload.wikimedia.org/wikipedia/commons/1/19/Britishentomologyvolume6Plate703.jpg, that includes the wingless female, but not at sufficient detail in the image (I can’t speak to the print original) to be able to say what details are distinguishing for the female E. defoliaria and E. tilaria.  Thank you for operating a wonderfully useful site.

We love BugGuide and we have no problem sharing your image.  Thanks for the compliment and additional link.

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