Tuesday, March 29, 2011

Pretty Polyphemus

Sunday morning I was able to witness my spicebush swallowtail emerge and spread his wings, and the same afternoon I was startled by some sudden scratching noises, and when I inspected my bug cage, a very large slug-looking "thing" was clambering over the other cocoons.  I quickly realized a female polyphemus moth (Antheraea polyphemus) had just emerged from her cocoon, so I scrambled to find my camera and wound up taking over 160 photos of her, most of which show 30-60 second intervals of the wing-expansion process.  While the spicebush swallowtail only took 15-20 minutes to fully expand his wings, large silk moth species frequently take 30 minutes to an hour to fully expand and dry their wings, and this polyphemus moth spent about 30-40 minutes.
Polyphemus moths are found in every state except Nevada and Arizona, and of course Hawaii and Alaska.  In northern states, they emerge in mid to late spring, and only have one brood per year. In southerly states, adults have been found in almost every month of the year, and there are often two to three broods per year.  Larvae feed on oak and maple, and the large green mature caterpillars may be seen crawling across lawns and parking lots in late summer looking for a place to spin their cocoon and overwinter.
I won't overload this site with an entire series of the photos I took, but here are a few that best show the complete process from emergence to flight.  To give an idea of scale, the cocoon is approximately 1.5 inches long, and the adult wingspan is about 5 inches.


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