Hornworm On September 10, 2010September 9, 2010 By MollyavalonIn garden, plants3 Comments Holy cow! This guy, and the two others I found, startled the daylights out of me. I've never seen such a huge worm - maybe 3 inches long and 3/4 inch thick. I threw them out in the native prairie. I'd been wondering who was taking bites out of the cherry tomatoes.