Meet the sweetpotato armyworm caterpillar, a reasonably common backyard denizen in the southeastern US, Central and South America. This particular fat little bugger had an uninterrupted evening eating the only one of my sunflowers to successfully bloom, and was not gracious at all when I pulled it off my sunflower and set it on the fence for the anole lizards to find. Its defense mechanisms included playing dead, spitting something noxious and neon green, and curling up into a little ball.
Here he/she is as originally encountered, looking all innocent, trying to pretend he/she didn’t just eat 30% of my sunflower’s leaf area in one evening. This caterpillar is about 2.5 cm long, with black triangular spots at its head and tail, possibly acting as eyespots. It is mostly brown, with some longitudinal, dark orange stripes, and a red head. It grows up to be a reasonably attractive brown and white moth. Although the common name is sweetpotato armyworm, the caterpillars are polyphagous and will eat just about anything — including, apparently, sunflowers (I’m not bitter).
The roll-in-a-ball defense, complete with light coating of whatever nasty, green substance it spit at me. The caterpillar remained in this position until left alone for about 15 minutes, at which point it uncurled and slowly meandered away.
Uncurled, and unrepentant.
It is loosely possible that this is actually an S. latifascia, a velvet armyworm moth, or S. ornithogalli, a yellow-striped armyworm moth, but I am leaning towards S. dolichos. Here’s the key I used to identify this caterpillar.