what caterpillar is this?
He was found on a grape vine but there are many trees nearby as well – including Cottonwood and Aspen. I don’t see a horn, but it looks like he’s thinking of making a cocoon so I don’t know if they pull their horns back as they prepare for that. I don’t see any hair – he’s very smooth.
This is an Achemon Sphinx Caterpillar, Eumorpha achemon. There are several color forms of this caterpillar, and yours is the green morph. We are copying Bill Oehlke on this response so he can add your sighting to the comprehensive species distribution data he is compiling.