15 July 2009

Callosamia promethea - the giant silkmoth





Yesterday I detailed the discovery of two cocoons of the giant Promethea silkmoth. Our household has lots of experience raising monarch butterflies from egg to flyaway, but we had never before encountered a silkmoth cocoon. With the monarchs one can tell when the butterfly will emerge from the chrysalis, because it turns transparent and one can see the orange/black wings inside the evening before the eclosion (emergence). These cocoons were opaque and mysterious, so we put then in a terrarium on the screen porch and waited. We didn't have long to wait...

The first clue occurred when we noticed the curious and anomalous occurrence of an abundance of very large black/brown moths hovering around our windows. A quick check of the terrarium revealed a beautiful female Promethea that had hatched the night before. I've embedded three photos above. The top two show her resting on a stick in the terrarium; in the third she's resting on my hand in direct sunlight for a better appreciation of her immense size and her reddish-brown coloration.

The females of this species emit their pheromones at the unusual time of about 4 p.m. until 7 p.m., so the males fly in daylight toward the females. Our female had probably drawn her suitors from a radius of several miles (the males are capable of traversing 20+ miles).

The successful suitor had to traverse a much shorter distance. As it turned out, the second cocoon in the terrarium was that of a male. I'll present him - and the result of their courtship - tomorrow.

All the photos enlarge to wallpaper size with a click.

9 comments:

  1. great pictures, I had one of these flying around in my garage the other night. My first impression was that it was a bat. When I opened the door and turned off the light he found his way out.

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  2. Wow! I actually found one of these in my back yard when I was a little kid -- I saw it just sitting there on a bush, went and got a big jar, tossed a stick and some grass in there, and then just picked it up by its wings and put it in the jar. I remember it was like the moth didn't even care I was grabbing it.

    After a day or two in the jar, I remember seeing little reddish-orange things stuck onto various leaves, I presume those were eggs?

    In any case, before letting it go, my giant moth and I were the hero of Show and Tell. I've never seen one of these again until now!

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  3. Awesome pictures. Do you have a flickr account I could follow? I'm assuming you probably take much more neat buggy pictures than you post here.

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  4. @linty - I've do have a Flickr account, but haven't uploaded any photos there; I'm not sure what advantage there would be to post photos there rather than on the blog.

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  5. Thanks for that! I saw one last night hanging out under my porch light here in middle TN and now I know the name! We get these and Luna moths a lot.

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  6. I just assumed you probably take a lot more pictures that I (and maybe others) would find interesting that you don't post because you don't want to turn this into a blog about your photos.

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  7. @linty - you're certainly right about the second part - I don't want the blog to be a storage site for miscellaneous photos (that's what Flickr is for). And I do have lots and lots of mostly nature photos. But posting them at Flickr would take some time, and that's ultimately the limiting factor.

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  8. Stan, you take beautiful photos. I've been wanting to ask you for ages ... What kind of camera and lens do you use, and do you do any kind of digital photo editing afterwards? If so which program do you use?
    Hope you had a lovely break from blogging ... We missed your posts here Down Under, though!

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  9. @Dr. Mieke - The camera is a subcompact digital (Nikon Coolpix 5200) that is at about 7 years old and markedly inferior to today's cameras because of its tiny previewing window. I got it because back then it a) was small enough to fit in a pocket while hiking, b) had a 3X optical zoom (good for that era but inferior today), and had a macro mode. I spruced it up by adding a memory card that allows me to take hundreds of pictures (assuming no flash use) because my lepidopteran subject matter doesn't tend to hold still for long and I wind up firing off 30 pix to get a good one.

    I edit using the iPhoto program that came with my Mac, but for the most part the only thing I do is crop (which serves basically as a sort of digital zoom since it's hard to get close to most butterflies). Sometimes I adjust brightness levels using the histogram, and sometimes I add sharpness.

    I appreciate your compliment, but let me (good-naturedly) suggest that you not offer the same "compliment" to a professional photographer. My understanding is that if you say to a pro "You take excellent pictures - what kind of equipment do you use" is equivalent to being served a wonderful dinner at someone's house and saying to the host/hostess "That was delicious food; you must have wonderful pots and pans."

    In my case, the beauty comes from the subject matter, not from the equipment or from any interventions on my part.

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