So, so gross. But, beneficial to the garden. This is the 2nd one I’ve found this week.
A natural predator of the tomato hornworm is a tiny beneficial insect called the braconid wasp. This wasp lays its eggs inside the hornworm. As they hatch, they eat their way out, killing the hornworm in the process. It’s a bit off-putting to see this creature on your plants, but you’re better off letting him be and letting the wasps do their job. Once they hatch, they’ll be enough braconid wasps to keep your garden hornworm free.