Observation notes: Colorado Springs, Old Farm Neighborhood, siding of house, sunny, 75 degrees, stationary not feeding. Single appearance at location (38°54'10.6"N 104°43'19.6"W
Verified by: A_baldini
Verified date: November 24, 2018
Coordinator notes: Definitely the tan-brown form of the distinctive Achemon Sphinx moth caterpillar as you suggested. I'm guessing there was a grapevine (the host plant) on or near the side of the house where you found it.