Look what I found while out weed-whacking in the yard:
(gloved fingers for scale)
That’s the larva of the black swallowtail butterfly. This good-looking caterpillar is colloquially known as a “parsleyworm.”
In these last two shots, check it out without and with the osmeteria (fleshy “horns” behind the head) everted in defense:
The osmeteria get to be about 3 times longer than that last shot, but I couldn’t photograph them in that fully extended state. As soon as they pop out, they begin to retract again.