Xylophanes sp. (Sphingidae)
I was excited to see yet another bag labelled "Sphingidae", but unfortunately for me (and the caterpillar) it had been parasitized:
You can even see the classic Sphingidae 'horn' in what is left of the deflated caterpillar body. An even better photo is below. This is a parasitized Xylophanes cthulhu caterpillar that I came across on the ACG caterpillar database - you can even see the eyespots still!
It almost looks like the paracitoid cocoon is dressed as a ghost for Halloween doesn't it? If the caterpillar that I observed today really is Xylophanes germen, it would be great to see this guy in its later instars - they are pretty intense.
Xylophanes germen (Sphingidae)
Photos below from the ACG caterpillar database
[relatively drab] Adult: