We had a real treat today when we found this unusual looking caterpillar on the O'Loughlin trail.  At first I thought it might be a small rubber child's toy. On closer inspection, I found it was a caterpillar and  very much alive.  While graciously photogenic in the middle of the trail, we moved the caterpillar to the side so no one would inadvertently take a wrong step.

Once home I googled the caterpillar to find it is a Spicebush Swallowtail, Papillo troilus, which turns yellow before it pupates.  More information can be found at http://www.butterfliesandmoths.org/species/Papilio-troilus