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.
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.