Polyphemus moth

2013 July 20

This is the first of two posts I’ve been saving for National Moth Week
So, we were driving back from the store on August 19, 2012, and were about a mile south of our house on our pretty low-traffic road when Sandy abruptly shouted “WOW!”, slammed on the brakes[1], jumped out of the car, and ran back down the road to pick up something. She came back with this gigantic, lurid green caterpillar:

This thing was a monster, over three inches long. It would occasionally extend its head so I could get a good picture.

If touched, it would tuck its head underneath.

To avoid being eaten, it evidently depended on a combination of green camouflage to blend in with leaves, and these defensive tubercles that look like they are probably at least irritating if not outright toxic.

Here’s a shot from the rear, because why not. It looks like those two areas that look like cuts in its green skin are expansion zones, allowing it to pass some pretty enormous fecal pellets.

This is another case illustrating that when one finds a caterpillar, it is important to get the photographs right away, because that night it started to cocoon up:

The cocoon ultimately became a white, fuzzy egg-shape.

Now right away, this is clearly one of the Giant Silk Moths, in the family Saturniidae. These are some of the largest moths in the world, and since there are only a relatively small number of species, it wasn’t too hard to identify. From the lime-green color, tubercle color, and pattern of white markings on the side, it looked to me like a Polyphemus Moth caterpillar, Antheraea polyphemus. But to be absolutely sure of identifications, one wants to raise caterpillars to adulthood.

Saturniids in general overwinter as cocoons, and the recommended way to rear one to adulthood in our climate is to store them someplace near freezing, not too dry, with a constant temperature. Some people dig pits in the ground and cover them with a board, or maybe store them in the vegetable crisper in a refrigerator. In our case, the cellar entrance to our old house fits the bill pretty well. It has one of those slanting cellar doors covering some stairs. So I put the cocoon into a mesh insect cage, and left it on the cellar stairs for the winter.

When spring finally came[2] in May, I took the mesh cage out of the cellar entrance and put it in a protected spot near our front door so we could keep an eye on it. It took quite a long time after that to mature, finally emerging from the cocoon on June 24, 2013[3].

Yep, it was a Polyphemus moth, all right. It was so big, I had a hard time getting it all into the field of view of my camera (I was standing back about 4 feet to take this shot):

Here’s another picture for scale – that’s Sam’s hand in the upper left corner.

It was a little hectic getting the pictures, because Rosie kept bouncing around saying “I wanna hold it! I wanna hold it!” It was fairly easy to photograph at first, because it had to warm up its flight muscles for a couple of minutes by vibrating its wings before it could take off. But, ultimately, it got its wings working and flew to the window. By this point, I thought that we had enough pictures, so we just opened the window and let it go. They don’t feed as adults (as you can see from the lack of obvious mouthparts), so they have a limited lifespan and I felt we had already kept it away from its mating business long enough.

I had considered trying to get eggs from it to raise up, but I’m pretty sure it was a male based on the very fluffy antennae, so that obviously wasn’t going to happen.

If it had been a female, then I would have put it outside in the mesh cage to lure in a male, captured him, and then put them together to mate. The males can scent a female from miles away, so if we had a female, and there had been any males around, they would have found her. Oh well, maybe some other time.

[1] Sandy usually drives when we go anywhere. She has better reflexes than me, and is better at noticing things in the road. If it had been me driving, I probably would have missed seeing this caterpillar altogether, or not registered what it was until we were so far past that I would have had a harder time backtracking to find it again.

[2] The winter of 2012-2013 was kind of weird. It didn’t really start snowing seriously until almost the middle of January, about a month later than usual. But then we went through the rest of the winter without a significant thaw, so that there were still a couple of feet of snow on the ground right up until the first week of May. So pretty much everything that comes out in the spring was delayed for just about a month.

[3] As it happened, it waited until I was out of town on a long trip to emerge, but Sandy saved it for me so I could get pictures as soon as I got back.

5 Responses
  1. July 20, 2013

    How beautiful. It’s sad they don’t live very long as moths.

  2. Carole permalink
    July 20, 2013

    Wonderful find

  3. Katbird permalink
    July 20, 2013

    What a nice surprise for Moth Week! Thank you.

  4. Bridget permalink
    July 22, 2013

    The moth looks so fluffy, I wanna cuddle it lol.

  5. jc lowe permalink
    October 7, 2015

    This is the most beautiful catapillars I’ve seen. I found it crawling across my bottom most step and imeadily hopped on the web to identity the speacies so that I could learn. more about it and where it lives.

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