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American Great Poplar Hawk Moth (Pachysphinx Modesta)

Poplar Sphinx larvae.

I reared some Big Poplar Sphinx from eggs to adult moths and I was pleasantly surprised just how large and stocky this moth is. It is a relative of our Poplar Hawk, and so some of the moth's markings are similar with a crimson patch upper side of the hindwings but it does not rest its hind wings above its forewings like our Poplar Hawk. The adult moths do not feed.

Wild find in Western Nebraska.
I was contacted on the 27th August 2012 by a teacher who lives in Western Nebraska, she found a female Poplar Sphinx, which laid eggs before she released it back into the wild. She said it would be a great experience for her class and was asking advice on how long from eggs to pupae as they are in a severe drought and the trees are going dormant and losing there leaves early.
I did reply with some advice, normally it would not be a problem as this female is from a second generation eggs take about 10 days to hatch and 4 to 5 weeks to a full-grown caterpillar which I think is quite fast.
you can change to another food plant if you have to although the larvae will wander about at first. The larvae grow to a huge size and do very well on cut branches in water. The twigs or branches must not have gaps near the water or the larvae will push through and drown especially a full-grown larvae looking for the earth to pupate  

The larvae feed on Poplar, Aspen and Willow.

Origin: North America.