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A Couple of Moths

Monday, December 07, 2009 10:19 PM | Anonymous
     I'm still in the practice mode with the new camera, but you can already tell that I am enamored with the macro capabilities of the little machine.  In spare moments today, between exciting emails, pulling weeds, and ducking out of the cold drizzle, I managed to take a couple of close-up shots of moths which had sought shelter on the Refuge HQ building.  Here they are:

Mythimna unipuncta_sm.jpg

     This buffy little moth is an easy one to find.  It is the Armyworm Moth, Mythimna unipuncta (formerly Pseudaletia unipuncta).  It is one of the "LBJ's" of the moth world (little brown jobs), about 1 inch long.  The slightly two-toned buffy color of the forewings, with just a dull dark stripe through the middle and a couple of vague pale spots are the basic marks to help identify it.  It is a common moth, distributed worldwide, and a member of the largest family of moths, the Noctuidae, which has about 20,000 species worldwide and nearly 3,000 in North America.  Charles Covell (see below) describes this species as a major pest of many plants, including alfalfa, corn, other grains, vegetables, young fruit trees, etc.  He mentions further that "armyworms are named for their feeding habits--they feed in fields by the thousands at night, then migrate in large groups to new areas when their food supply is exhausted" (Covell, p. 105).  There's no telling what the caterpillar of this moth might have been eating around the Refuge HQ.  (A search for information on this moth on Google even found 15 blog postings about the critter!  I guess I'm #16.)

     Next up is a little jazzier critter but again quite common:


     The intricacy of the patterns on the wings of many moths can be endlessly fascinating--and endlessly confusing--to anyone who takes the time to look closely.  This is the Bent-lined Carpet Moth--and, no, they don't eat carpets.  This is another smallish moth; it's wingspan is barely an inch.  The scientific name is Orthonama centrostrigaria (more recently placed in the genus Costaconvexa).  It is a member of the second-largest moth family, the Geometridae, or "geometers".  The larvae of moths in this family are the familiar "inchworms" which make their way along twigs or leaves with their funny looping crawl.  This species is distributed over much of North America; the larvae feed on species in the Knotweed family such as the knotweeds and smartweeds (Polygonum and Persicaria spp.).  It might also feed on dock (Rumex sp.), one species of which occurs as a weed in the lawns around the Refuge HQ.
     Identifying this Carpet Moth wasn't quite as straightforward as the Armyworm.  I had a hunch it was in the Geometrid family because of the triangular forewings and the multiple wavy lines across the wings...but that just narrowed it down to one of several thousand species.  Even though this species is illustrated in Covell's field guide, I identified this the hard way: My favorite moth photo resource is the Moth Photographer's Group, maintained by the Mississippi Entomological Museum at Mississippi State University.  It's not for the faint of heart; you kind of need to know what family or families of moths to begin looking in.  Even then, thousands and thousands of species are illustrated.  But the good news is that they present crisp, coordinated "plates" of illustrations that are easy to rifle through--much easier and more complete than any of the published field guides.  I was getting pretty bleary-eyed after having looked through hundreds of species of geometer moths on that website when I finally stumbled upon a match.

     There are just a few good general guides for identifying moths, most of the North American moth literature appearing in rather technical publications.  (See, for instance, this introduction to moth publications on the Moth Photographer's Group website.)  The best known book is Charles Covell's "Moths of Eastern North America" in the Peterson Field Guide Series published by Houghton Mifflin (1984).  Much harder to find and much sought-after is W. J. Holland's "The Moth Book", originally published by Doubleday in 1903 in a hardbound edition and subsequently reprinted in paperback in 1968 by Dover Press.  A very good reference list of moths for the Austin area was compiled by James Gillaspy at the University of Texas's Brackenridge Field Lab on Lake Austin Boulevard.  You can find an introductory (read: meager) list of the moths of Balcones Canyonlands NWR--as of 2008--in this pdf document.  That list is already out-of-date; it doesn't have either of today's moths!


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