I'll make one guess then I'll give a shout out to the folks over on the butterfly/moth forum. @mellielong @jimard8
May be a Yellow Striped Armyworm aka Spodoptera ornithogalli - if this is a correct guess I don't need to ask what plant it's feeding on because this type feed on many different plants.
We have a Forum called "Gardening for Butterflies, Birds and Bees forum: September 2015 Butterflies, Moths & Larva"; (there is a new thread each month); you may want to visit over there. Lots of good photos of caterpillars, butterflies and moths.