Polyphemus Moth Metamorphosis in Photos

Geek Culture

Polyphemus moth caterpillarPolyphemus moth caterpillar

The fat green caterpillar, done eating and ready to cocoon.

Like any good parent I’ve read my kids The Very Hungry Caterpillar (in English and Chinese) countless times, and it’s a fun book both for its subtle anti-junk food propaganda as well as the fun depiction of one of nature’s most impressive magic tricks: the metamorphosis from a this crawly worm-like thing into a beautiful fluttering creature. However, it’s not one that we often get to see ourselves. My kids and I have found a few small caterpillars in the past and fed them leaves until they cocooned. Most of the time we just ended up with Miller moths which, let’s face it, aren’t really impressive in their moth state. I’ve got photos of a caterpillar (nicknamed “Shiny”) from a few years ago and the resultant pupa, but none of the final moth stage — apparently I didn’t feel the need to get a photo of a dead brown moth.

Polyphemus moth Caterpillar frontPolyphemus moth Caterpillar front

Awww, look at that face.

Last fall, however, we came across a most impressive specimen: that plump caterpillar you see above was on my back steps. It was about as big around as my index finger, maybe about two inches long or so. I quickly scooped it up and put it in my daughter’s bug-catcher container along with a few leaves and twigs in case it was still hungry. It turned out that it wasn’t; that very evening it started building its cocoon by wrapping a leaf over and adding lots and lots of silk. By evening it was completely wrapped up in a little bundle.

Caterpillar cocooningCaterpillar cocooning

The caterpillar began working on its cocoon.

Thanks to the internet, I was able to track down the most likely suspect: our guest was a Polyphemus moth caterpillar. According to one site we found, the antheraea polyphemus has two broods, one that hatches in early spring, cocoons and emerges in summer, and then another that hatches in fall and overwinters in its cocoon until late April or May. Well, that sounded pretty cool, so we decided to hang onto the cocoon and settled in for a long wait for the adult to emerge so we could find out if we were right.

Cocoon completedCocoon completed

The completed cocoon in the bug-catcher.

We had the cocoon in the bug-catcher container in our front hall for a while, but then when the weather cooled down and we started running our heater, we worried that maybe that would confuse the moth into emerging earlier. (I’m not an entomologist; I have no idea if the emergence is based on ambient temperature, time elapsed, or what.) So we put it out on the front porch where it sat for several months. (My daughters continued to check on it occasionally, but eventually we started ignoring it.)

In April, we started thinking about it again: when will it come out? How big will it be? We decided that if it really were a polyphemus moth, it wouldn’t have space to spread its wings in the little bug catcher, and so we procured a butterfly garden (sort of a pop-up screened cylinder) and transferred the cocoon to it, along with some rocks and twigs and leaves.

And then it sat some more. And sat. And sat. We checked the cocoon nearly daily through the month of May. Nothing.

By the middle of June, I began wondering if our cooler-than-usual spring was delaying it, or if maybe it had died. How would we know? How long were we going to wait? We still tried to check daily, but sometimes we forgot.

Last night — at long last! — the moth emerged. Unfortunately, we didn’t get to see its actual emergence so we didn’t see the wings when they were limp, but I did get some nice photos of the adult moth before we let it go. This one is apparently a male (because of the fuzzy antennae).

Front view of the polyphemus mothFront view of the polyphemus moth

The front polyphemus moth with its fuzzy antennae.

Our moth was about five inches wide, and it sat unmoving at the bottom of the butterfly garden while I took some photos. I left the lid open after taking the photos, and by morning it had flown away — hopefully to find a mate and start the next generation of caterpillars.

polyphemus mothpolyphemus moth

The Polyphemus moth gets its name from the large eyespots.

I took a few photos of the cocoon afterward:


Side view of the empty cocoon.


Cocoon and close-up showing the hole where the moth emerged.

It took a long time, but it was definitely worth the wait, and we were just lucky to find the caterpillar. If we spot any more interesting caterpillars in the future, I plan to put our butterfly garden to use again!

All photos by Jonathan H. Liu

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