Hi Ken,

I believe this is a waved sphinx moth caterpillar! The characteristic seven stripes on the side of the body in addition to the yellow band or "crown" around the head indicate it is likely a waved sphinx moth. 

Lime hawkmoth caterpillars are only found in Europe. 

What a fun find! If you found it near the ground, it is likely getting ready to burrow in the soil and pupate (turn into a cocoon). 

Waved sphinx moths host on a variety of plants including ash, hawthorn, lilac, oak, privet, and more. 

We have about 30 species of hawkmoths/hornworm species in Colorado! Here is a fact sheet about them: https://extension.colostate.edu/topic-areas/insects/hornworms-and-hummingbird-moths-5-517/

Let me know if you have any other questions! 

Thanks,

Lisa

Lisa Mason
Horticulture Specialist, Entomologist
Colorado State University Extension, Arapahoe County