ID Guide 7: Eoreuma-Diatraea-Donacaula

From our recent Timberlake bioblitz, it was clear that we were (collectively) confusing at least three different Crambid genera which have elongate triangular cream-colored wings. We labeled images of apparently the same individuals or similar moths as Eoreuma, Diatraea, and Donacaula. I was getting quite confused so I went back to sources including MPG, BOLD, and BG (not assuming everything there was properly IDed) and here’s what I think I’ve figured out:

Eoreuma: FW outer margin fairly square and rather straight. Veins are pale, flanked by fine dark speckling. The “discal dot” is at the end of the FW cell. Five species have been recorded in Texas but by far the most common one is E. densellus which occurs in Central, South, and East Texas.
http://mothphotographersgroup.msstate.edu/species.php?hodges=5492

Diatraea: FW outer margin fairly square and rather straight. Veins are darker than ground color, flanked by pale strips inbetween. I’m not seeing any small dark speckling along the veins. Discal dot is at end of FW cell same as Eoreuma. The two most common species in Texas appear to be D. evanescens and D. lisetta both of which are primarily found in deep E Texas.
http://mothphotographersgroup.msstate.edu/species.php?hodges=5478
http://mothphotographersgroup.msstate.edu/species.php?hodges=5481
(D. lisetta has rows of brown spots across FW.)

Donacaula: FW is much more pointed with an angular acute tip. In most species/examples, there is a dark brown streak through the length of the FW. Discal dot is actually beyond the FW cell. Eight spp. recorded in Texas; most widespread is D. mellinellus.
http://mothphotographersgroup.msstate.edu/species.php?hodges=5316

Based on this review, I think I’m seeing primarily Eoreuma densellus among our Timberlake “catch”.

Posted by gcwarbler gcwarbler, October 10, 2019 03:07

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I believe I have a moth similar as well. One at the moth sheets and a daytime observation. Had not had a chance to look them over well yet. Hopefully will post tomorrow.

Posted by mikef451 8 days ago (Flag)
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Of course, we also had plenty of Agriphila vulgivagellus which is more elongate and tubular, with long dark palpi; pretty easy to pick out.
https://bugguide.net/node/view/44969

Posted by gcwarbler 8 days ago (Flag)
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Thanks Chuck! As always! :-)

Posted by annikaml 8 days ago (Flag)

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