Tuesday, September 23, 2008

It's never easy. Why do I always expect it to be easy?


Sometimes identifying a species that I don’t know turns out to be harder than I expect it to be. This was true years ago when I was just learning bird species, and it’s true today. For some reason, the field mark that always jumps out at me, and which I’m convinced is the one to focus on, never turns out to be the one I need to identify whatever critter or plant I’m looking at.

That was painfully obvious to me again two days ago. It was evening, just before bedtime, when I heard a noise at my bedroom window. At first, I didn’t even realize the sound was coming from my window. It sounded like a soft and fast rat-a-tat noise. I thought perhaps they were discharging unused paintballs over at the paintball field, but that was long dark. Then I thought my heat had come on, but I haven’t turned my heat on yet. Still, I went over to the heater under the window to feel the baseboard just to be sure. And then I saw it. My first thought was a bat. I thought I had a little fruit bat at my window. How cool! Then I looked again. It was a moth! And not just any moth. It was the biggest most I’ve ever seen in my life. This moth was easily 5+ inches across.

From inside, the underside of said moth was a typical mothy color—various shades of brown. So I rushed outside with the camera, determined to try for a photo. That’s when I got the one you see here. Still, as it was dark outside, and both the flash and interior light affected the moth’s color, I couldn’t really tell what markings it had or much about its colors.

I wasn’t overly concerned, though. I had a semi-decent photo, a good moth book, and really, how many giant moths this size can there be? Wrong. There’s lots of them.

After hours of investigation, my best tentative guess is that this is a Polyphemus moth, one of the largest of the giant silk moths. Here's a link to some nice info and a much better photo of one in daylight. My moth is probably a female, as its antenna isn’t very bushy. I had to lighten the photo somewhat to see the eyespots. What really threw me in the identification is that the edges of this moth’s wings are very worn and raggedy, which I thought was how they were supposed to be. So I was looking for photos of giant, raggedy-edge winged moths.

However, the Polyphemus moth’s flight begins in August and this being late-September, I guess that’s what happens after they’ve been out in the world for a month or so.

The size of my moth fits the size of the Polyphemus, as does the location, the timing of its appearance and the abundance of host plants such as oak, beech, sassafras, hickory and wild cherry. So that’s what I’m calling it—unless any of you have a better idea.

7 comments:

Lynne said...

WOW Carolyn! That's the biggest moth I've ever seen. Frankly, I didn't know they grew that large. That's a very nice link too. I wish there were something similar for Minnesota.
I know what you mean about zeroing in on the wrong field mark. I've done it more times than I can count.

Carolyn H said...

Lynee: here's link you could try: http://www.butterfliesandmoths.org/map

You can pick your state and even county for searches. The only bad part is that some states and areas aren't well filled in. It's worth checking, though.

Carolyn H.

Lynne said...

Thanks for the link Carolyn- that's the best site I've seen yet.

Seabrooke said...

Your moth isn't a Polyphemous, though those aren't uncommon. Polyphemous are more colourful, with very distinct eyespots and bold lines. Rather, I believe your moth is a Black Witch. They're giant dark butterflies. Kaufman's guide to insects has this to say:

"The huge Black Witch (Ascalapha odorata) is mostly tropical, but strays wander far to the north every year, sometimes reaching Canada. Amazingly, there are records of large numbers of Black Witches traveling within the eyes of hurricanes. "Fallouts" of these moths have arrived with hurricanes coming ashore from the Gulf of Mexico, where they must have been flying continuously for several days."

Do you think yours came up with Ike?

Carolyn H said...

Seabrooke: you may well be right that this is a black witch moth. The resemblance to a bat is certainly correct, as it the size. It certainly would have had to come north with Ike, I would guess though, because Pennsylvania sure isn't its normal range. Thanks for the tip! Nice link, too!

Carolyn H.

Carolyn H said...

Seabrooke: PA has only had a single sighting of a black witch moth, according to the butterflies and moths Web site. I've submitted my photo to the state coordinator for PA to see what they say about it. I'd love to think that this sighting could result in York county being added to the range map for this very cool moth. Thanks again!

Carolyn H.

Seabrooke said...

Great idea submitting the sighting to butterfliesandmoths.org, I suspect there tend to be a lot of sightings like this that slip through the cracks because people don't think to tell anyone. I'd also recommend submitting it to BugGuide.net - I understand they have experts who review the submissions regularly and it's a great way to help spread knowledge. Another person who would be extremely knowledgeable about range and records is Bob Patterson of Moth Photographers Group. I think he also monitors BugGuide.net but he'd also be appreciative of such a record.

It's a really cool moth, and I'm envious. I gather they're regular strays, but very rare. I have a friend who's been mothing in southern Ontario for nearly a decade and has yet to see one; it's on his Most Wanted list.