An impossible ID

Rather than bury the lead, I'll address the title directly. It is so difficult to distinguish a “Desmia maculalis” from a “Desmia funeralis” that BugGuide has a dual-species classification for the Desmia genus: “funeralis or maculalis (Desmia funeralis or maculalis),” http://bugguide.net/node/view/3967

This is the second Desmia I have seen. Last August I photographed one and initially I wasn’t even sure if it were a butterfly or a moth. I looked through images of all the skippers (butterflies) and then proceeded to look through all of BAMONA’s [adult] moth images.

I finally found “Desmia maculalis” and “Desmia funeralis.” I could determine that I probably photographed a female, and this one may or may not be a female, but one lousy shot wasn’t enough to ID the species then or now.

How does one tell a “Desmia maculalis” from a “Desmia funeralis”? Read on if you dare!

“From Brian Scholtens: ‘The character that I use is the extent of the white patch on the underside of the abdomen. D. funeralis individuals have a solid white patch on the underside of the abdomen on segments 1–5 (or may have a slight break on segment 3). D. maculalis individuals have a broken white patch, where about 1/2 of segments 3 and 4 are clearly dark. Basically, maculalis looks striped on the underside, whereas funeralis looks like it is basically solid white.’

“There is considerable size overlap between male Desmia maculalis and female D. funeralis so it is necessary to sex the moth to be able to identify the species. Fortunately, sexing the 2 species is relatively easy.
» Males of D. funeralis and D. maculalis have a distinct notch or joint at about the mid-point of each antenna.
» The hindwing spot on the females of both species is pinched in the middle and on rare occasions may be divided into 2 smaller spots.

“To be able to safely identify the 2 species, these 3 things are needed;
1. a dorsal photo that clearly shows the antennae or the spot on the hindwing so the moth can be sexed.
2. a ventral photo clearly showing the markings on the abdomen. The moth does not have to be killed or chilled to get a photo of the underside. A jar with flat sides works great for this purpose and also makes it easy to get accurate measurements.
3. an accurate measurement of the wingspan”
From: http://www.butterfliesandmoths.org/species/Desmia-maculalis

From BugGuide—
Desmia funeralis = Grape Leaffolder - Hodges#5159;
Desmia maculalis = Grape Leafroller - Hodges#5160.
What’s the difference between a “leaf folder” and a “leaf roller”? I have no idea!

My one, lousy photograph last August led to quite an education! I submitted the photo to BugGuide: http://bugguide.net/node/view/985931

1 year ago (“Birds do it. Bees do it. …”): http://365project.org/rhoing/365/2014-05-29
2 years ago (“Melted peppermint sticks”): http://365project.org/rhoing/365/2013-05-29
3 years ago (“Waiting for the clouds to clear…”): http://365project.org/rhoing/365/2012-05-29
4 years ago (“In the yard…”): http://365project.org/rhoing/365/2011-05-29

[ IMG_2417S12x9tm :: f/2.8 :: 1/25" :: ISO-800 ]