Ento-musings from the University of Kentucky Department of Entomology

Tuesday, July 24, 2012

Moth 2: National Moth Week

Blake Newton, UK Extension Entomology

Today's moth is a tough one. Why? Take a look:

I found it in my garage a couple of weeks ago and I took a picture of it specifically for this"moth week" blog project. Now, I regret it. I should have found an easier moth to identify!

To me, this one is hard to identify because it is a medium-sized gray and/or brown moth. In the U.S., there are literally hundreds of species of medium-sized, gray and/or brown moths. Many of them are very closely related to each other, and they all have very similar body shapes and structure, so the only differences between many of them are in the colors found on their wings. I'm not colorblind, but, honestly, all of the gray and brown patterns look the same to me (heck, the patterns on butterfly wings look the same to me too, so I guess it doesn't have anything to do with gray and brown).

So, at first glance anyway, this one is a very typical gray and brown moth. Some clues: it was a little bigger than what I would call medium-sized. The pegs in that pegboard are 1" apart (center-to-center), so the moth was about 1" long. That's actually pretty large for a moth. Also, this moth showed up at night, so it is probably a night-flier. That's not much of a clue--most moths are night fliers. But this fact may help me to eliminate a few possibilities down the road.

When looking at a brown or gray moth, my first thought is always "noctuid." Noctuid is a name used for moths in the family Noctuidae. The word is also used (informally, and sometimes incorrectly) for a few other kinds of moths, some of which were once a part of Noctuidae family, and some of which are closely related to Noctuidae. There are many species  of these so-called noctuids. The family noctuidae alone includes about 3,000 species in North America. MANY of these are gray or brown, and around 1" long. From a picture, there is no single, reliable way to tell whether a moth belongs to the family Noctuidae or not. As far as I know, the best way to identify this creature is to hunt for pictures on the net. So let's go!

Instead of going for an entomology textbook or Bugguide, the first thing I do is a Google Image search for "gray moth rusty." I used those terms because the moth is mostly gray (that's the way it looks in the photo, anyway) and it has some waves and blotches that look, to me, like a rust color. The first few results didn't look anything like my moth, but about 100 images in, I found something that looked similar but not identical. Here it is, at a blog maintained by Dave H. Small: http://goo.gl/YkBIR

Like I said, the moth isn't exactly right. The rusty blotches aren't in the right places. But it looks like it might be related to my moth. It's name, according to Dave H. Small, is the "Ultronia Underwing," Catocala ultronia. Dave's I.D. might not be exactly right, but I'll bet that he's close. This seems like a good lead, so it's time to check Bugguide. Is my moth closely related to Catcala ultronia?

Well, here's how to identify Catcala ultronia, according to Bugguide: "forewing pattern predominantly longitudinal (running from base to outer margin), rather than transverse (running from costa to inner margin) as in many other Catocala species; typically has dark brown to black strip along inner margin, and similar-colored subapical patch extending from outer margin to PM line or reniform spot; central longitudinal area light gray or brown, but the extent and intensity of shading varies considerably among individuals; pale brown patch usually present along costa at apex; hinding dark orangish-red, rarely pinkish or yellow, with complete black median band and wider black terminal band; small white patch at apex; antennae filiform; sexes similar"

Ah, come on, man. I've been an entomologist for 16 years now, and that sounds like gibberish to me. Entomologist are supposed to talk tarsomeres and sternites, not "black strips" and "white patches." Damn it Jim, I'm an entomologist, not an interior decorator. And how can a pattern be "predominantly longitudinal"? A color pattern is a two-dimensional field and it doesn't have direction!(!!!)

So that description is not really useful to me. Not yet, anyway.

From Bugguide's entry for Catocala ultronia, I back up one step to the Catocala genus page here: http://bugguide.net/node/view/368/bgimageCatocala is indeed in the family Noctuidae, and it represents the so-called "underwing" moths. Underwings are distinguished by their brightly-colored hind wings. These colors are hidden when the moth is at rest, like the moth in my photo. I have seen many underwings before, so I am somewhat familiar with these moths, but I did not realize that they all belonged to the same genus. Nice! The next step is to check is the number of species. 110 in North America. Gulp. And something else from this page: these moths are known for the "challenge of identifying specimens (many are difficult to distinguish from one or more similar species)." That sounds like pep talkin' to me!

I'm still not convinced that my moth is an underwing, or even a noctuid, but this is as good a place as any to start. It's time to look at a bunch of pictures. So at the top of the Catocala page I click "images", which leads me to Bugguide's collection of images for moths in this genus.

For those of you who are not familiar with Bugguide, here's the deal. It's probably the most important resource on the internet for the identification of insects (photographed insects, anyway) in North America. Bugguide is organized by its users: people send in photos and ask for them to be identified. Other users look at the photos and move them into the correct place on the site. Bugguide is used by professional entomologists, amateur hobbyists (who often know insect I.D. better than the pros!), and anyone else with an interest in insect identification. Bugguide isn't perfect. It's not useful for insects that are difficult or impossible to photograph (such as insects that live inside leaves or wood). And there are some insects that are truly impossible to identify from photographs. And sometimes the bugs are "filed" in the wrong places on the site(these errors are usually corrected quickly, though, by other members). But I use Bugguide almost every day in my job. It's not an exaggeration to say that Bugguide has changed entomology (and for the better, I think!).

Here's another minor problem with Bugguide: every picture that gets sent in, stays in. So there are often hundreds of images of single species, including ones that are easy to identify. And sometimes you have to look through all these to get to the one you want. For the genus Catocala, Bugguide has 63 pages of images! A typical Bugguide page has about 20 pictures. That's a lot of gray and brown moths. And not nearly enough bullets.

Click. Click. Click. That's me clicking through the first 12 pages of Catocala. All of the images on the first 12 pages are not identified any further than "Catocala". These images are not very useful to me, except to show me that, yes, there are a few moths here that look a little like mine, so perhaps I'm in the right place. These unidentified images also give you an idea of how difficult these moths are to identify. It may also mean that there are a few species that haven't been officially cataloged by scientists! I hope that my moth isn't one of those.

Click Click Click Click Click Click. More pages, no matches. Soon, though I get to Catocala ultronia again. Hmmm... it still looks the most like my moth. Gotta keep clicking, though.

Clickity-click. Lots of interesting names here. Peninent Underwing... Little Underwing... Serene Underwing... Woody Underwing...

Wait a second. Woody UnderwingCatocala grynea, you say? Light gray wings... rusty stripes and blotches. This looks a lot like my moth! Best match so far and by far. Close enough, at least, to suggest that I am in the correct family and genus. But let's keep looking through Catocala for even better matches.

I see a few other candidates. Charming Underwing comes closest, but it's no contest. Wood Underwing is my best bet. And its info-page checks out: this moth is found in my area, its about the right size, and it flies in June. Unless I'm way off, and my moth is from some other genus or species, I'm fairly sure that the creature in my photo is Catocala grynea.

Am I 100% sure? No way. Identifying insects from photos is a fun game and it can be instructive, but it isn't science. The moth pictured above is Catocala grynea right up until someone tells me that I'm wrong!

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