This lovely creature is a tomato hornworm. Yes, it is as large as it looks. Over a half inch of width and at least three inches of length. Some might think the 'Ewwww' of the title refers to this lovely creature, but I find them quite beautiful. They almost glow in the sunshine and they are such a clean fresh crisp shade of green. They are quite magnificent.
No, the 'Ewwww' is for this poor unfortunate shrunken individual. Sometimes, tomato hornworms are parasitized by other insects. In this case, a braconid wasp, a tiny stingless wasp, laid her eggs on the body of this tomato hornworm. The many larvae lived inside the live hornworm, eating its insides gradually without yet killing it. When they were mature, these larvae chewed their way through the hornworm's skin to the outer surface, causing fatal injury, where they spun tiny cacoons, pupated, and later emerged as adult wasps to mate, after which the female goes off to find another host hornworm on which to lay her eggs.