Last night I was sitting on the couch, maybe 2-3 yards from my cham room, and I kept hearing this grating sound. I kept going into the room but it would stop before I could locate the source. It was really weird. And then finally I was able to track the sound to one of my hornworms just grating away with it's little lets/jaws/whatever haha It was so creepy, I didn't know they made noises, and I've been ordering them for years. But it validates why I don't like them crawling on my hands with those sharp little icky things.