This close up captures the color of it's glow. I think this was a 5-10 second exposure.
Curious observers soon arrived and examined the sight with their red flashlights, which lit up the scene.
I quickly realized that some context was essential to the photograph. The shadow of my tripod can be seen next to the glow.
A friend tells me that most likely it's parasites in the caterpillar that are creating the glow -- another subject to look up sometime.