One of my parent's neighbors discovered this massive caterpillar on the side of the road while coming over for a little chat:
What a gem.
Vivid green and startlingly bright reds.
A brown head that was kept hidden for most of the evening. Looks a bit like a walrus with the brown noggin and fuzzy whiskers, eh?
Have I mentioned that this guy was GIANT? And ROTUND? He looks like a bright green turd; but with fancy red dots. A turd with chicken pox.
So: for identification. We're not sure, but we're leaning towards an Antheraea polyphemus also called the polyphemus moth. I had tentatively identified it as a luna moth (check out the luna caterpillar here) until I discovered they only inhabit areas east of the Great Plains. Way off, sonja.
A bit on the polyphemus moth from wiki:
When the eggs hatch small yellow caterpillars emerge. As the caterpillars age, they molt 5 times (the 5th being into a pupa). Each instar is slightly different, but on their fifth and final instar they become a bright green color with silver spots on their side. They feed heavily on their host plant and can grow up to 3-4 inches long. They then spin cocoons of brown silk, usually wrapped in leaves of the host plant.