Achemon Sphinx Caterpillar

Subject: What bug is this?
Location: Southern Oregon
July 21, 2016 1:41 pm
Location: Medford, Oregon
Bug: Looks and moves like a caterpillar, but it can pull it’s head into it’s body
Markings: Looks like an eye near it’s tail
I raise Monarch butterflies and it has the same waste product as a monarch caterpillar, so it must be a leaf eater.
Very unusual insect, and quite large, I’ve never seen anything like it.
Signature: Tracy

Achemon Sphinx Caterpillar
Achemon Sphinx Caterpillar

Dear Tracy,
The Achemon Sphinx Caterpillar,
Eumorpha achemon, in your image is the only member of its genus found in Oregon.  It is a member of the Hawkmoth or Sphinx Moth family Sphingidae, and the caterpillars from this family are called Hornworms.  The Achemon Sphinx Caterpillar is a little unusual among hornworms because it loses its horn as the caterpillar grows and molts, and all that remains is a caudal bump which you likened to an eye.  This may serve as protective mimicry, and its ability to retract its head, which you also observed, is a defense mechanism as well.  According to the Sphingidae of the Americas site, food plants include:  “Parthenocissus quinquefolia Virginia creeper, Vitis Grape, Ampelopsis Vines and Ivies” so we are guessing there is one of those plants near where the sighting occurred.

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