The wasp had paralyzed it and was probably making its way to a burrow where it would place it along with an egg. Morbid, I know, but the caterpillar gets eaten alive.

Are only the motor neurons affected? Or are sensory neurons anesthetized too? If both are disabled, being eaten alive might be as blissful as having a nap on the couch. But if a wasp's "venom" acts like curare, the senses remain intact during paralysis.
(See bizarre account of a man who allowed himself to be completely paralyzed by curare.)

According to some research mentioned by Chapman in The Insects (1), the venom affects neither sensory input nor motor output. He mentions a neuromodulatory effect based on where the injection occurs. I think it basically means that by stinging in a particular spot, certain motor functions (leg movement, say) can be stopped. For the specific wasp and prey mentioned, it would consistently sting first in one spot and then in another.

It all makes me glad I'm not on the menu.

This guy is officially nuts in my book. So, I guess by his account the caterpillar feels every bite...